CA2289582C - Breakaway support post for highway guardrail end treatments - Google Patents

Abstract

A breakaway support post is provided for a highway guardrail system to enhance the safety of a vehicle impacting with either the rail face of the associated guardrail or one end of the guardrail facing oncoming traffic. For some applications, the breakaway support post may be formed from a steel I-beam with one or more elongated slots formed intermediate the ends of the steel I-beam. The slots are preferably formed in the flanges of the I-beam which are in turn aligned generally parallel with the associated guardrail. For other applications, a breakaway support post may have an upper and a lower portion with a rotatable coupling assembly disposed therebetween. A shear pin or other releasing mechanism is preferably provided to maintain the upper and lower portions generally aligned with each other to the impact of a vehicle with one end of the associated guardrail.

Description

:BREAKA.WAY SUPPORT POST FOR
HIGHWAY GIJARDRAIL END TREATMENTS
TECHNICAL FIELD OF THE. INVENTION
The present. invention relates to highway guardrail systems having a guardrail mounted on posts, and more particularly, to guardrail end treatments designed to meet applicable federal and state safety standards including but not limited to crash worthiness requirements.
BACKGROUND OF THE INVENTION
Along most highways there are hazards which present substantial danger to drivers and passengers of vehicles if the vehicles leave the highway. To prevent accidents from a vehicle leaving a r~ighway, guardrail systems are often provided along i:he side of the highway. Experience has shown that guardrails ;should be installed such that the end of a guardrail facing oncoming traffic does not present another hazard more dangerous than the original hazard requiring instal~_ation of the associated guardrail systems.
Early guardrail ;systems often had no protection at the end facing oncoming traf:Eic. Sometimes impacting vehicles became impaled on t:he end of the guardrail causing extensive damagE: to the vehicle and severe injury to the driver and/or ~~assenc~ers. In some reported cases, the guardrail penei~rated directly into the passenger's compartment of t'.ze vehicle fatally injuring the driver and passengers.
Various highway guardrail systems and guardrail end treatments have been developed to minimize the consequences resulting from a head-on impact between a vehicle and the extreme en-d of the associated guardrail. One example of such end treatments includes tapering the ends of the associated guardrail into the ground to eliminate potential impact with the extreme end of the guardrail. Other types of end treatments include breakaway cable terminals (BCT), vehicle attenuating terminals (VAT), the SENTRE end treatment, and breakaway end terminals (BET).
It is desirable for an end terminal assembly installed at one end of a guardrail facing oncoming traffic to attenuate any head-on impact with the end of the guardrail and to provide an effective anchor to redirect a vehicle back onto the associated roadway after a rail face impact with the guardrail downstream from the end terminal assembly. Examples of such end treatments are shown in U.S. Patent 4,928,928 entitled Guardrail Extruder Terminal, and U.S. Patent 5,078,366 entitled Guardrail Extruder Terminal.
A SENTRE end treatment often includes a series of breakaway steel guardrail support posts and frangible plastic containers filled with sandbags. An impacting vehicle is decelerated as the guardrail support posts release or shear and the plastic containers and sandbags are compacted. A cable is often included to guide an impacting vehicle away from the associated guardrail.
A head-on collision with a guardrail support post located at the end of a guardrail system may result in vaulting the impacting vehicle. Therefore, guardrail end treatments often include one or more breakaway support posts which will yield or shear upon impact by a vehicle.
Examples of previously available breakaway posts are shown in U.S. Patent 4,784,515 entitled Collapsible Highway Barrier and U.S. Patent 4,607,824 entitled Guardrail End Terminal. Posts such as shown in the '515 and the '824 Patents include a slip base with a top plate and a bottom plate which are designed to not yield upon lateral impact.

When sufficient axial impact force is applied to the upper portion of the associated post, the top plate and the bottom plate wall s~.ide relative to each other. If a vehicle contacts the L~,pper part of the post, the associated impact forces tend to produce a bending moment which may reduce or eliminate any slipping of the top plate relative to the bottom elate. Also, improper installation of the top plate relative to the bottom plate, such as over tightening of the associated mechanical fasteners, may prevent proper functioning of the slip base. A breakaway support post is al:>o shown in U. S . Patent 5, 503, 495 entitled Thrie--Beam Terminal with Breakaway Post Cable Release.
Wooden bre~~kaway support posts are frequently used to releasably anchor guardrail end treatments and portions of the associated guards°ail. Such wooden breakaway support posts, when properly installed, generally perform satisfactorily to minimize damage to an impacting vehicle during either a rai:L face impact or a head-on impact.
However, impact. of a vehicle with a wooden breakaway support post may often result in substantial damage to the adjacent soil. Removing portions of a broken wooden post from the soil is ofi~en both time consuming and further damages the soil. Therefore, wooden breakaway support posts are often insta:Lled in hollow metal tubes, sometimes referred to as foundation sleeves, and/or concrete foundations. For some applications, one or more soil plates may be attached to each metal sleeve to further improve the bra=akaway characteristics of the associated wooden post. Such metal sleeves and/or concrete foundations are relatively expensive and time consuming to install.
Light poles, sign posts or similar items are often installed next t:o a roadway with a breakable or releasable connection. For some applications, a cement foundation may be provided ac~jac:ent to true roadway with three or more bolts project:inc~ fxvom true: ~ournd..~t: ion arc>und the circumference of the pole. ~'ari.ous types of frangible or breakable connec;t.L011S may be ~c~rme.ci between the bolts and portions of the light polex c7r sign ~~c>s?:.
SUMMARY OF THE INTENTION
In accordan~::e with s:~r~f~ asr~ec:t of the present invention there i.s provided a roadway guardrai=. system, comprising: a guardrail; at least one support post having an upper ~..>orti.on airica ,~ ~..c.wt~.:r portion, t: he upper portion having a lower end and this lcower porti«n having an upper end; tr°~e upper portion k:aei_ng coupled to the guardrail and the l..ower port i.orbe ~ ng structurE~d and arranged to be located ira the eaxtt~; the upper: portion lower end compris:i.ng a first rrcernber anc~ the lower portion upper end compri ~>ing a secc_;nd tn~~mb'.>r. ; the first and second members being coupl_ec~ togetA"ter with at 7_east two rods, the rods laying aie>r~g t~rv irrvag:inary line that extends in a st:r'orag c~i.z. ec~~ :i ca.r;, w.hr~ :ei.r: t.t~e pcast es;hibits a high mechanical strength in the strong direction, there being a weak dinec~tion that is generally perpendicular to the strong direct:i.on, wl~ere_irn tree supp~,:ort post e:~hi.bits a low mechanical strength i..n the weak direction; at least one spacer located between t~.he f ir~t and second members, there being a gap on ate ;..ease:. core s:i.de of the :imaginary line, wherein the upper port.ican ~,~an rotate relative to the lower portion in the weak direction when subjected to a force; and tr~.e upper uruc:~ l c:~wex ~:~c:o:rt.::ioros comprise I-beams, each of the I-beam portions haVir~c:~ a web, with the web of the upper portion being generally aligned with the web of the lower po:~ti.c>r~, arnd wa_t.h the imaginary line extending generall y in t:he same d::.rect s on as the webs .

In accordance w:it.h arlot:her azspE~ct o:~ t.he, present invention there :_s provided ,:z rc>sr~"~wa,y~ c~uardrai:l ;system, comprising: a qua.rdrail.; at least one support post having an upper aart.ion and a lower partion, t:he upper 5 portion having a lower er~ad arid 'rul;:~wer portion having an upper end; the l.zpper pcor:t:i.c>n be:'~ nc~ cou~>lect to the guardrail and tr:e _'E owes por:t.i.<.n bea.ng structured and arranged to be located i.rz r.~~e eart:h; the upper portion lower end compri.s:ing a first member and the lower portion upper end comprising a seoond member; the first and second members being coupl_f,~~::1 t~.agett~er with at ~ east two rods, the rods layi.rlc:~ a>.e.ory are i.nnac~inary 1 one that extends in a st.reng di.rect~c~z~, whtareirn the past exhibits a high mechanical strength in the strong direction, there being a weak dire,vtion that.: i.~ ger~eral:Ly perpendicular to the strong direct. ion, whei:ein true supp~.:~~~t: p<ast. e:hi.bits a low mechanio.al strerm~th in tl;.e w~=.a,k cti:rection; at least one spacer locate3 betweer~~ tre f i rst .:end second members, there being a gap on au least one side of the imaginary line, wherein the upper port: ion ~~~:~n rotate relative to the lower port.i.on in t.h~Y weak. directioru when :~ub;~ec:ted t.o a force; and the spa~~ez: c,:om~;~rises a p.roje~a:ion that extends from one of the first and seco.zd members and that bears on the other of tkze f i r.t anc~ sec:v.ond members .
In accorda.ncEr wit~..h yet ao.otrm:r aspect of trze~ present invention there is pro~~ri.dec~ 4z rc:>adway guardrail ~~ystem, comprising: a ~uardras.:i ; .at 1.~~~~::zst one support post having an upper portion and a lower portion, the upper portion having a lower end arid the Ica~wer portion having an upper end; tree u~>per ~>o:r:t-~i.au bei,nc~ ccyu~>led i~o the guardrail and th~.a lower ~>ot:-tic~r7 k~e~.nc~ stract~.zrE:d and arranged to be l.c.acated ~.r. the earth; the upper ~>ortion lower end comprising a first member and the lower portion upper end comprising a sec:can<~ memb~>r; the first and E~
second members being co~xplc~d toget=ruer with at :i.east two rods, the rods lays..nc~ ~v.c:ar~g an ~..maginary lane that extends in a strong direction, wherein the post exhibits a high mec:hanic~al. st:rengttu i.n the ~.ct:.r.cvnc~ direction, t=here being a weak d.ir_e.:tic~n th<xt ~. s ger~F~ra~.ly perpend~_cular to the strong direction, wherein the support pe:~st exhibits a low mechanical strengt.r:: in true w~.~~:~k c. i.rectian; at least one spacer located betwee.nn t;.2°~~--V f:i ~,~t. xrod second members, there being a gap on at least one side of the imaginary line, wherein th.cv: upper i:~c~:rt:i_on can rotate re~_ative to the lower Aortic>n in t:he weak di.zec:t::a.ocn when sub:ec:ted to a force; and the spacer ;:omprises twc_> pro~ecticjns, with each projection E;~xterzdi.ng frr~~m a respective onF~~ of the first and sec:or~ci members, thF: p.rcjec.:tion:~ ~xenerally bearing on each other.
In accordarucc,.. with still yet anoti~er aspect of the present invent:.i_on there i:~ pr.:c:>vi.caed ~: breakaway% support post for mounting a guardrail. thereon as part of :~ highway guardrail system comprising: aru ~:langated body Ir axing an upper portion acrd a lower pc~ut:..ic>r.; a rot-at:abl.e coupling assembly disposed between the j:~ppe:r portion and 1-he lower portion of the elongated boc.~y; the upper portion of the elongated body r~asTing a fi:r-st:: c:nc~; t::r:~e lower pc:~rtion of the elongated bony having a sec:c,nd end which may be inserted into the soil ad~ac::ent to a roadway: nueans for attaching the guar~dra:ii. ac~_jacc°rn: t ctrce first en.d of the upper portion; and means> f«r re'.e~xsab~.y securing the upper portion of the elongated body in a :.generally collinear alignment with the lower pc:~r~t:::a.ozu >f the elonga ted body such that an impact with on~~ end c~t_ them attacshed guardrail will tend to rotate the upper portiorn of the elongated k>ody relative t.o the :Lowe:e pc~~ tric:~r~ of the elc>ng~~ted body and the breakaway support po~:t wi',.1. ~~esist ~~ rail face impact with the guardrail.

~a In aceordanca wz.th still yet another aspect of the present inventiorthere is provided ,~ breakaway support post for mounting a guardrail thereon as part of a highway guardrail system ~om~>riair~u~ : an ~ ~ oruUated body having an upper portion anc~ a lower ~::or::,a~t:ic»-~;~ t~lne upper pc_>rt:ion of the elongated body have. rig ~-..~ f i r=t end; t_.he lowe r portion of the elongated body h<~vi.ng a ;~ecr~nd end; means for attaching the guardrail adjacent to thc=? upper portion; and means for couplirug the f.:irst. er~d c~f t.lie elongated body with the secor,,d ~Ynd of the elor:gat.ed k~ody L;ucr, that an impact with one Eaa~d of r_.he atk=a~:,he<:~ gma:~~rc~rail wi.l1rend to rotate the upper ~:~orti.cm of the el~:>o~gat:ed body relative to the lower portion of the elongated body and the :breakaway support post will resist a rail. face impact with the guardrail..
Ire accord<~nc~~ wit.r: st~:ila. yet aruother aspect of the present invention the.r_Fa is p~rovide~d ~:~ roadway guardrail system comprising: a guardrail; at: Least: one support post having an upper pardon and a lower portion, the upper portion having a i.awer end ax°uct the :~ow~r portion Having an upper end; the upper ~ac~:rt, i..on b~~inc~ coupled t:o the guardrail and t:.he lower pr.:frt:i~,:>n t:~eirzg insert: able into the earth; the upper portion lower end x;~eing pivotally coupled to the lower portion by a hinge, the hinge havincx a pivot pin that extends ire a ~tr:or~g direction u~hich is substantially ~>er~~endicv.zla:c~ t.ra t:he gua:rc~z~ail.., wherein the post exhibits a sigh mechara.:~ca:l strer~gt:h i.n the strong direction, the hinge having a we<:k di..rection that i.s generally perpendicular to: the stra:>ng direction, wherein the upper portiorL c:an. riotate ~~:lati~re to the lower direction from an irnpac:~t. irz t::he wE:aK direction; and the Hinge is releasably restrained fr~:or~~ pi~~oting by a shear pin, the shear pin being sma.t.lm: -'~n ~.;~i_arneteaz: than the pivot pin.

6 k.:~
In accordance with still yet. another aspect of the present invention: tHere :i.~~ ~:~ro°~rided a su~>port post for mounting a guardrail thereon :z:. part of a highway guardrail system, comprising: a fzr~t elongated member having first and seconc:t eru~s, w:i t.I-~ t::.r:~e fi~i.rst erid of the first member adapted ~~c~ c:ec::ei-ve ,:~ <;u~:irdrail; a second elongated member having fi. rst-. and. second ends, with the first end of the second member being irisertable into the ground adjacent t:o a:~ r:oric~.way; c:~n~~ cyf the second ends having a first. bracket w:it~h :~ generall.y U-shaped configuration extending therefrom; the other of the second ends having a second bracket extending therefrom; the second bracket; L.>eing rec.:c'i.ved i_~v t he first U~-shaped bracket; the first and second nrackets being coupled together by a piri extend:i.ng a_Long an axis substantially perpendicular t:o a rc::c~E=ivacx ~.auarc~o~::~iL, whexei.n 1-~.he~ first and second membexs a.re rc:>t~at:~_~L~l.y c:~o~.z~:~lc>d; and the first and second members being maint.ai.nec-i iri a first position by a shearable body extending between: the second bracket and at least a portion; of k:vrae :~:i.r~;:;~.: U-~~;r~a~>ed bracket.
Ira accordance with sty l~_ yet: another aspect of the present invention there ~_s provided a support post for mounting to a guardraa_ 1 ~~~~ ~:ar.Tt c:: f ~:, riighway c:~uardrail system, comprisi.nc~: a:~ ~:i.x:~;~t:. ~:--bearr~ Having firat and second ends, with the first end of the first I-beam being structured and arranged t.o c:ouple tc~ the guardrail; a second I-beam h.avirig :f.irst and sec:c~rad ends, with the first end of the second I-beam ~::~c,in:a insert ak~l-a into glue ground adjacent to a roadway; each of the first and second I-beams having a web and flanges, with ttie flangE:es at the respective second ends l~~av:~n.rx extEeru:;.lons protr~.zdi~~xg beyond the web; the extensions of t:he f:i rst. I-beam being located adjacent to the extensions of the second I-beam, the extensions of the f.i-rst: anc.~ ~c~:~onct :I ~-L~eams being pivotally 6=
coupled together by a hinge pin .=~o that the t=ir.st and second I-beams pi~rot about an axis ;:haT:_ i.s parall.el to the web of the j first I°-ka~:arn raetweerz a lengthened, substantially co.li.r..ea:r pc>s:i.t.icar~ arad a non-collinear position; and ~ he fir~~~t and sec~.~nd I-bears being maintained in the Z.engtLwne~cl pcy~ .i.t.i~>n by a shearable member extending between at :Least ori.e ~,>f the extensions of the first T-beam and at least one :W taue extensions of the second I-beam.
In accordance w:i.t:ru stw i 1.:L y~~t ar~<,rther aspect of the present: invention th~~r~-~ :i..::; p:rov i;ae:;:d ,:r roadway gu~~rdrail system, comprising: a gua:rdrai.l; at least once support post having an upper portion and a lower portion, the upper portion having a lower end and trre lower- portion having an upper c=nd; the ~appf~.z~ pc,>:~:~t.:i.c;.rn L:~eing coupled to the guardrail and the lowf:.;t: ~>c:>rt:ic:>n b~~i_r~g i:nse:rt,~b7_e into the earth; the 1_ower end r~.f tt-~E:~ upper portion being coupled at the upper. end to thc:~ lower portion by a rotatable coupling that rotates ak>c3ut. an axis when the post is impacted en a dvrec:tz.on tlna~_ i~ generally parallel to the guardrazil, tht~=: ,axis bf~i.r~g substantially perpendicular to the guard:r~a~i...3, thE. ~>c:y~t; exhi.biti:rig a high mechanical strength i.n the di..r.ec:tion ofi the axi.s,: and the rotatable coupling having a frangible connection for maintaining the upper port.ior~ irr arv upright alignment with respect to the lowar pc:~xt:.i~:oro..
In accordanc{~ wi.th sti.::Ll yet ancthe:r aspectT of the present invention there ~..:. prov i.ded a breakaway :~uardrai.l post for highway crash control systems comprising: an upper post member having c~ weak impact: axis and a strong impact axis; a l ower~ post tT~d~mbe.r° ~.ai.spc~sed beneath and spaced apart from said u~:>pex ~:oost rc7.errlber; a c~:>nnecting joint member havir~.g a fii:v;i; ~~nd .zo.ld ~ second Fend, said first end of said joint. member connected at said first end by a first fasa..ener to said ~.appe.r~ post member and connected at sai:~ second end by an attachment to said lower post member, said first: fastener having a first failure strengttn Less traari a se :°~and failure strerrgth of said attachment; sa~.d f.ir5t: f.a~:~;::en~-~z- having a first connector having a first f:~:~.lur~~ ~7trer~gttu and a second connector having a second fa:.i.:a.urP strerogth; and said f~_rst failure strength greater than said .~~ecc~nd failure strength such that upon ari impact L<..m~:e being applied along said weak impact axis, said wer_.s,:>rz~;:~ c:c~rnraec~~or fai:Ls anal said upper post. memo>er rotates ,:~bc:u.,at. s<ri.c:::k f:irv~C: connecaor.
In accordance with st~.:L.:~ yet another aspect of the present invention there i.s prov.:LdE~.d ~r roadway guardrail system comprisinga a guardrail; at; Least. one support post coupled to said g!aardrail and c;orrr~~=r:z sirog an elon~~at:e body having a first poLtiora anc~ ;~ :_aec:o~r~c;i ~>ortic.m a:rran.ged in a substantially r.~~lli.n.e<~r r.-~.s.tionsh.p; a 'frangible connection for caupling the first ~;~ortion with t:ne second portion, the frangible conne~aion including a rotatable coupling assembly disposed between thE. first portion and the second. portion. of ttue h:e:lc:>rwgate ~:.fc:o y; and the ~_rangible connection oriented .rel..at:i~rt~ t:c~ th~:~ c~uardrai.l. suc:n that an impact with one end of the guardrail coupled to the support post will tend t.o buckle the support post and such that the support post wil_L rwsist aru impact with a rail face of the guardrail.
In accordanc:f~ with st:i .:11 yet another aspect of the present inventi..on there i.p.rovi.ded a breakaway guardrail post for highway crash control systervs comprising: an upper post member having rtr weak impact: axis and a strong impact axis; a lower: pa:>t mernber° diaposed beneath and spaced apart from. said u~.:>pe.rv pose. rcrernbe.r; a. c~.:>nnecting joint member having a firs: end ~::~r~c~ ~ second end, said first end of said joint. member r.:onnected at said first end ~5 E:' by a first fastener to said upper post member and connected at said second end by a .~ecc.~nd fastener to said lower post member, said t~rst~ fasteaner having a first failure strengtYi :Less than ra ~~e~~~>rud tailux:~e strength of said second faste:ruery :~ai~~ f:ir;t: fvastu~zuez: hav:irzc:C a first connector having a first. fa:~..ln.~re strength and a second connector having ,a second fa:i:lu.re :~trengt.h; and said first failure strength greater than said sec~:and failure strength such that upon are impact t:~rce bo.lng applied along said weak impact axis sa~.d s~ec.~cor7c~ c;c~r~r:m>.rtr,~r~ fails and said upper post: member rotatE~s a:zb<:»a~:. sGrir,:3. first. conned or.
In accordance w.it.h st -L:L f. yet arm:~ttier aspect of the present invention there i.s prc~vic~c:,d .:~ breakaways- support post far mounting a guardrail t~'ier~':<_>r1 <~s part of a highway guardrail system d:i.spo~,~~~d acm~ja~:~ent to a :roadway comprising: an a :Long2at.ed. t:>cacl~y~ w~-~ i~.::h i~ws:i.st.s impact by a motor vehicle from a strong d:a.rec~rl.~:>n and yields t=o impact by a motor vehi~.le from a weak d:i_rection; the weak direction and 'the strong c:~irectioro disposed substantially perpendicular t;o .:-each c:~t:ht.~z: ; t. rte t~::L r~nc:~yated body having a first end and a -sec~ocmi errc~; ~~tre ~~.l.cmc:Cai::ed body having a cross section operable t.o be o.z:~ieru::tad with respect to an attached guardraa.l whereby an i_mpa~:.a. from the weak direction with one end of an attached guardrail will tend to buckle the breakaway support pcast and the breakaway support post. ~ai.l.~ r~=.sist ~-a rail. ::ace :impact; from the strong direction with ar: a~=:t.ac;herl c;~uardrail; and the elongated body operable t:o be driven directly into the soil adjacent to the roadway.
In accordance with stl:ls yet anotter aspect of the present invent_LC>rl there: i.s p;.~ovi ded ~~ breakaway :>upport post for mounting a guardrG~:_:a. v~riere~c;n as part of ,~ highway guardrail system ~~omprising: <~n e:lon~~at.ed body operable to resist an impact by ~3 motor' ~JE?h~ C_~e from a strong f~ f direct:LOn and opea~able t:o yie.:l.c:~ .ire :r:esponse too an impact by a motor vehicle f rom a weak c:~ix:e~.C:,~.arn: t:he weak direction and the strong d:i..rec*~.ic:~n cia;~;poseci ::>~tb~t.anti.all:y normal. to each other; the weak c~ix~ec::t c.or~ ox z. errt:es:i c~enE~rally°
para11e1 with an attached guardrai.:l_; t:hc? s1:. c~«nc, direction oriented generally perpendi..cular with an at.tvac.~;hed guardraLl,; means for attaching a gi.xardra:il adjacent ::c> The first end of the elongated body; a plurality of oper~::i.ngs formed in the elongated body intermediate the first end and the second end; arrd the elongated body Yuaving a cross section operable to be oriented ~~~ith res,~~c~ct: t.c~ 'vt~e attached guardrail whereby an impacts f rcrcr t.h~:~: we~:~ k: as i..x ecvt::ic;rr w ith o:ne end of the attached guardrai..l wi:L 1. k:.end t:~_> buc::kl.e the breakaway support. post p:roximatYe t;t~e. opena..r~c~; and tree breakaway support. post wi_1.1. res:_st ~ r~.~:i~. :~ac::e irnpac;t: with the guardrail from the: strong d.i.rect.ion.
In accordance with sti.:Ll. yet. another aspect of the present invention there i.s prcavic~ed or roadway guardrail system, comprising: a guardrail; at least one support post defined in part by= an I--k°~e.arct having a web and flanges; the suppcart post Yiav:i.rrg a r:ir:~r~ end and a second end; the first Enc. coup:l_ed tc:~ t:aue c:p.aa:m.~c:~r.~:il and the second end operable i~o be Located i.n t:.l:c~ e,:~rth; each flange having at least cme open:i.ng forrnec:a tYve:rein and disposed near the surface of the ~aar:tY; wh~wn the support post is located in the earth; and the openings defining :an part a frangible connect_a_on between the f a. rst and secora.d end of the support past whereby are irrEpat~t: with one e.Y~d of an attached guardrai:L will tend to L.7uckle the support post and the support post will resist ~i ra.:'il face impact with an attached guardrail.
Tn accordance with still. yet another aspects of the present invent.ic~cz thE~r~~ J..s ~:3rov:Lcac~ei l support past for rnounting a guarc~raii_ thex:~~c::>n a~~ p~~a~t of a highway l guardrail system compri.sir:g: an elongated body having a first portion deffining a first end of the elongated body and a second pc:>rtion def miry ~ :~ecand end of the elongated body; a frs:~nc~i.b:Lc~ c.°:c~arznec,t.:ior c~c~upling ~h~e f_irst portion with thc: seccanci pe>rt::i corn; i:kae irr.angible c°onnection operable to be oriented re.lat;.:i.ve t c::~ ax, attached guardrail such that an impa~,t w.a.th one Enc. of thø~ attached guardrail will tend to buckle the support past; and the frangible connection operat~le to tae oricr~ted relative to the guardrail such t.r~at t:h<~ support. ~ar.,s;~t w.i.l.l resi:>t a rail face impact with t:he :~t~l:acYz~:cl c:~ua.r~.:::lr ~~.:i7 .
In accordance with sty l l yet an<::sther aspect of the present invention there is provided ,a roadway guardrail system, compris:lng: a guardrail; at least arse support post, the suppoa__°t post ~.o:cnpz°.i.s_i.rzc:~ ,:~:,~ C-x.~eam hav_~~.ng a web and flanges, the support 1>c~~s,i:: hav.c.r~t~ a fi.z~st end and a second end, the first end be:i.ng c~o~..apled to the guardrail and the second end being structar~~d a:-ld arranged to be located in the earth; crud ahe tl_anges having vertical slots therein loc~:ated near ttu.e svr.°~acE: ~:af the earth when the support post is loc:atec.~ in t:he ~aaxth.
In accordance w~.th sti.l.l.. yet:. aracyther aspect of the present. invention there is ~~ravided :~ support post far mounting a guardrail thereon as part of a highway guardrail system ~~:omprisir~g: an elongated body having a first portion and .~ second pc:7rt:.:i.on,: ~~ t rangi:ble connection .for coupling the f:ir:~t~ pC>rt:ia::~ra wi.t ~~ t;l-uv second portion;
and the frangible connect:i.c:>r~ orriente~~ relative to the guardrail whereby an impact with one end of the guardrail will tend to buck_~e the suppa!~~t post and the supuort post will resist a rail facie im~~ac;t wi_t:t~~ the guardrail.
In accordanc:<:3 wi th s t: i ~l..l ye t anct: l;.er aspect of the present invent a. an t.herE i.s prc~va~ tied ~;~ breakaway support post for mounting a guardrail. therec;n as part of ~r highway ~h guardrail system ~,::ornpr:is.inc~: an e.i~::~rrg~~tAd body defined in part by an I-beam having a web and :Larrges; the support posts having a f:i. rvst ernd ~r;c:i <~ ;,~:c.:~c:~rad ~~rnd; the f i:rst end operable to be ccupled to a r:~uaxdr~il and the second end operable to be loc::ated in tim earth ad 'ac:.ent to a roadway;
each flange havinc.~ at lc~as,t ~;~rn~~ c>~>~:=_rl:i.rn.,a formed ther~sin and disposed near the surface of trhe ear~.h when tha support post is located in the ~-Y>axth; arwi trm openings in the flanges cooperati.ri.g w:iti~ e:.aa::~kr other t.c> <rll.ow an Impact by a vehicle with one end of an attached guardrail to buckle the support po:>t wand t~c~ aZ l_caw the .>l.rpport post to resist a rail face impact dry a vEhi.c.le:~ t~a_i..th°1 ~~n attached gu<~rclrail.
Technical advantage's c:.~f t re present invention include providinc:~ breakaway suzp~,~ort posts w:rric:h are easier to initial:~_y ~..nsta:~_1 and to re~~air as compared to wooden breakaway support po5t~s. Ma j<_~r portions of each breakaway support post. m~iy be fake:::icaat.c~ri f~rc~m standard, commercially available steel I-beams using conventional metal bending and stampi.nc~ tn;.:>c~hn:i<~~..~a~s :irl ac:cordarnce with teachings of the present i.r~.v~erat::i.c:r~, C,~rm or more metal soil plates may be attached ~o Each breakaway support post to further enk~ranc=.=~ c~.e;~i.rv~:::~ ::::rrar_ac:teri.:atics of yielding or buckling during heed-~on impact with one end of an associated guardrail to minimize damage to an impacting vehicrle anti to ~>ecrare:l y srrrc:~hcar they a=>soeiated guardrail to redirect an im.pactinc~ veh.ic~le back. onto the adjacent roadway after a rail face impact.. breakaway support pasts ir;,a.:o:rp~>x~at:irAc;~ t~e~:r~_:i-~incrs of the present invention may be used with a wide variety of guardrail end treatments ha;rinc~ ~~ar.ic~~z,~~ types cf energy a:~btsorbing assemblies locatec:~ at. c:>r rl~:ax: t~r-sc~ e~rW of t:he a;~sc>ciated guardrail facing oncoming t.raffi.c. Fc>r many applications, breakaway ,::~up~oc>rt~ posts rnay be satisfactorily iristall.ed ad~ja~~ent ta:~ the edge of a roadway without t:he use oaf sUeel.. r ca~.zrvd<~tion tubes and/or concrete foundations t~rpi~~r~i.. ~ y as:~;c:>c~ i_<:~tf~d with installing wooden breakawa~,~~ support hosts and other types of breakaway support posts.

A further aspect of the present invention includes providing guardrail support posts having a first portion or upper section attached or coupled, at least in part, by a frangible connecaion, to a second portion or lower -section.
The support post and frangible connection may be oriented in accordance ~rith teachings of the present invention to resist impact by a motor vehicle from one direction (strong direction), and to yield to impact by a motor vehicle from another direction (weak direction). Preferably, the frangible connection allows the upper portion of the post to deflect slightly and then break off of the lower portion, thus minimizing lifting of the impacting vehicle into the air.
BRIEF DESCRIPTION OF THE DRAWINGS
For a more complete understanding of the present invention, and the advantages thereof, reference is now made to the following written description taken in conjunction with the accompanying drawings, in which:
FIGURE 1 i;s a schematic drawing showing an isometric view with portions J~roken away of a highway guardrail system having a breakaway support post with a guardrail mounted thereon in accordance with one embodiment of the present inventic>n;
FIGURE 2 is a ;schematic drawing in elevation with portions broken away showing a side view of the highway guardrail system of FIGURE 1;
FIGURE 3 is a schematic drawing in section of the breakaway support posit taken along lines 3-3 of FIGURE 2;
FIGURE 4 is a schematic drawing showing an isometric view with port~_ons k~roken away of a highway guardrail system having a brealsaway support post with a guardrail mounted thereon in accordance with another embodiment of the present invention;' FIGURE 5 is a schematic drawing in elevation with portions broken away showing a side view of the breakaway support post of FIGURE 4 in its first position;
FIGURE 6 is a schematic drawing in elevation with portions broken away showing a side view of the breakaway support post of FIGURE 5 rotating from its first position to a second position in response to a force applied to the breakaway support post in one direction corresponding with an impact by a vehicle with one end of the associated guardrail;
FIGURE 7 is a schematic drawing showing an isometric view with portions broken away of a highway guardrail system having a breakaway support post with a guardrail mounted thereon in accordance with a further embodiment of the present invention;
FIGURE 8 is a schematic drawing in elevation with portions broken away showing a side view of the highway guardrail system of FIGURE 7;
FIGURE 9 is a schematic drawing in section of the breakaway support post taken along lines 9-9 of FIGURE 8;
FIGURE 10 is a schematic drawing showing an isometric view with portions broken away of a highway guardrail system having a breakaway support post with a guardrail mounted thereon in accordance with another embodiment of the present invention;
FIGURE 11 is a schematic drawing in elevation with portions broken away showing a side view of a breakaway support post analogous to the breakaway support post of FIGURE 10 rotating from its first position to a second position and separating in response to a force applied to the breakaway support post in one direction corresponding with an impact by a vehicle with one end of the associated guardrail;
FIGURE 12 is a schematic drawing showing an exploded, isometric view with portions broken away of an alternative embodiment- of breakE:r bars suitable for use with the guardrail system illustrated in FIGURES 10 and 11;
FIGURE 13 is a schematic drawing in elevation with portions broken away showing a side view of the breakaway support post oj_ FIGU:EtE 10 utilizing the breaker bars of FIGURE 12 and rotating from its first position to a second position and separating in response to a force applied to the breakaway support post in one direction corresponding with an impact by a vE~hicle with one end of the associated guardrail;
FIGURE 14A. is a schematic drawing in elevation with portions broken away showing a detail side view of a breakaway support poet incorporating a further embodiment of the present invention;
FIGURE 14H is a schematic drawing in elevation with portions broken away showing another side view of the breakaway post ~zf FIGURE 14A;
FIGURE 15F. is a schematic drawing in elevation with portions broken away showing a detail side view of a breakaway post =~n accordance with still another embodiment of the present invention;
FIGURE 15E~ is a schematic drawing in elevation with portions broken away showing the upper portion and the lower portion of the breakaway support post of FIGURE 15A
disconnected from each other;
FIGURE 15f is a schematic drawing in elevation with portions broken away showing another side view of the breakaway support post of FIGURE 15B; and FIGURE 16 is a schematic drawing in elevation with portions broken away showing a side view of the breakaway support post of FIGURE. 15A rotating from its first position to a second position i.n response to a force supplied to the breakaway support post in one direction corresponding with an impact by a vehicle with one end of an associated guardrail.

DETAILED DESCRIPTION OF THE INVENTION
The preferred embodiments of the present invention and its advantages are best understood by referring to the FIGURES 1 through 16 of the drawings, like numerals being 5 used for like and corresponding parts of the various drawings.
Portions of highway guardrail system 20 incorporating one embodiment of the present invention are shown in FIGURES 1, 2 and 3. Portions of highway guardrail systems 10 120, 220, and 320 incorporating alternative embodiments of the present invention are shown in FIGURES 4 through 13.
Breakaway support posts incorporating further embodiments of the present invention are shown in FIGURES 14A through 16. Highway guardrail systems 20, 120, 220, and 320 are typically installed along the edge of a highway or roadway (not expressly shown) adjacent to a hazard (not expressly shown) to prevent a vehicle (not shown) from leaving the associated highway or roadway.
Guardrail systems 20, 120, 220, and 320 are primarily designed and installed along a highway to withstand a rail face impact from a vehicle downstream from an associated end treatment. Various types of guardrail end treatments (not expressly shown) are preferably provided at the end of guardrail 22 facing oncoming traffic. Examples of guardrail end treatments satisfactory for use with the present invention are shown in U.S. Patent 4,655,434 entitled Energy Absorbing Guardrail Terminal; U.S. Patent 4,928,928 entitled Guardrail Extruder Terminal; and U.S. Patent 5,078,366 entitled Guardrail Extruder Terminal. Such guardrail end treatments extend substantially parallel with the associated roadway. U.S. Patent 4,678,166 entitled Eccentric Loader Guardrail Terminal shows a guardrail end treatment which flares away from the associated roadway. ~nlhen this type of guardrail end treatment is hit by a vehicle, the guardrail will normally release from the associated support post and allow the impacting vehicle to pass behind downstream portions of the associated guardrail. However, breakaway support posts incorporating teachings of the present invention may bE~ used with any guardrail end treatment or guardrail system having satisfactory energy-absorbing characteristics for the associated roadway and anticipated vehicle traffic.
Support posts 30, 130, 230, 330 and 530 have a strong direction and a weak direction. When a post is subjected to an impact from the strong direction, the post exhibits high mechanica=_ strength. The strong direction is typically orient=ed perpendicular to the guardrail. Thus, when the post is impacted by a vehicle in the strong direction (such as when the vehicle impacts the face of the guardrail), the post will remain intact and standing, and the vehicle will be z-edirected back onto the road. When the post is subjected to an impact from the weak direction, the post exhibits low mechanical strength. The weak direction is typically oriented parallel to the guardrail.
Thus, when the post us impacted by a vehicle in the weak direction (such as when the vehicle impacts the end of the guardrail), the portion of the post that is substantially above the ground. will either break off or bend over, so as to avoid presenting a substantial barrier to the vehicle.
Preferably, the upper portion of the post will deflect slightly and th~sn break off, in order to minimize lifting of the impacting vehicle into the air.
One or more support posts 30, 130, 230, 330, and 530 are preferably incorporated into the respective guardrail end treatment to substantially minimize damage to a vehicle during a head-on impact with the end of guardrail 22 facing oncoming traffic. T:he number of support posts 30, 130, 230, 330 and 5:30 and the length of guardrail 22 may be varied degending upon the associated roadway, the hazard adjacent to the roadway requiring installation of highway guardrail system 20, 120, 220 or 320, anticipated vehicle traffic on the associated roadway, and the selected guardrail end treatment. As discussed later in more detail, breakaway support posts 30, 130, 230, 330 and 530 will securely anchor guardrail 22 during a rail face impact or side impact with guardrail 22 to redirect an impacting vehicle back onto the associated roadway. Support posts 30, 130, 230, 330 and 530 will yield or buckle during a head-on impact with the end of guardrail 22 without causing excessive damage to an impacting vehicle.
Support posts 30, 130, 230, 330 and 530 may be fabricated from various types of steel alloys or other materials with the desired strength and/or breakaway characteristics appropriate for the respective highway guardrail system 20, 120, 220, and 320. For some applications, a breakaway support post incorporating teachings of the present invention may be fabricated from ceramic materials or a mixture of ceramic and metal alloys which are sometimes referred to as cermets.
Portions of breakaway support posts 30, 130, 230, 330 and 530, as shown in FIGURES 1-16, have the general configuration associated with a steel I-beam.
Alternatively, the teachings of the present invention may be incorporated into a breakaway support post having a generally hollow or solid, rectangular, square or circular cross section.
Breakaway support posts 30, 130, 230, 330 and 530 as shown in FIGURES 1-16, have respective upper portions and lower portions with approximately the same general cross section. However, for some applications, the upper portion of a breakaway support post incorporating teachings of the present invention may have a cross-section which is substantially different from the cross-section of the associated- lower port:ion. For example, the upper portion may have the general configuration associated with an I-beam, while the associated lower portion may have a general configuration associated with either a hollow or solid cylindrical post or a hollow or solid square post.
In FIGURE~> 1, 2, 4, 7 and 10, highway guardrail systems 20, 120, 220 and 320 are shown having a typical deep W-beam twe7_ve (1.2) gauge type guardrail 22. For some applications, a thrie beam guardrail may be satisfactorily used. Other types of guardrails, both folded and non folded, may be satisf=actorily used with breakaway support posts 30, 130, 230, 330 and 530 incorporating the teachings of the present invention. Breakaway support posts 30, 130, 230, 330 and 53C~ may sometimes be described as direct drive support posts.
Various tec:hniquE~s which are well known in the art may be satisfactorily used to install breakaway support posts 30, 130, 230, 330 anc3 530 depending upon the type of soil conditions and other factors associated with the roadway and the hazard requiring installation of respective highway guardrail systems 20, 120, 220, and 320. For many applications, breakaway support posts 30, 130, 230, 330 and 530 may be :>imply driven into the soil using an appropriately suzed hydraulic and/or pneumatic driver. As a result, breakaway support posts 30, 130, 230, 330 and 530 may be easily rE~moved from the soil using an appropriately sized crane or other type of pulling tool. For many applications, breakaway posts 30, 130, 230, 330 and 530 may be satisfactori:Ly used to install guardrail 22 adjacent to an associated roadwa~,~ without the use of metal foundation tubes or other types of post-to-ground installation systems such as concrete wit:h a steel slip base support. U.S.
Patent 5, 503, 9:95, entitled Thrie-Beam Terminal With Breakaway Post Cable Release, shows one example of a breakaway support po:>t with this type of foundation.

As shown in FIGURES l, 2 and 3, breakaway support post 30 includes elongated body 32 defined in part by web 34 with flanges 36 and 38 attached thereto. Elongated body 32 may be formed by cutting a steel I-beam (not expressly shown) into sections having the desired length for elongated body 32. A pair of elongated slots 40 and 42 are preferably formed in flange 36 on opposite sides of web 34.
Similarly, a pair of slots 44 and 46 are preferably formed in flange 38 on opposite sides of web 34. Slots 40, 42, 44 and 46 are formed intermediate first end 31 and second end 33 of breakaway support post 30. Slots 40, 42, 44 and 46 define in part a frangible or yieldable connection between an upper portion and a lower portion of support post 30.
The length of breakaway support post 30 and the location of slots 40, 42, 44 and 46 will depend upon various factors including soil conditions and the anticipated amount of force that will be applied to breakaway support post 30 during a rail face impact with guardrail 22 and during a head-on impact with one end of guardrail 22. For the embodiment shown in FIGURES 1, 2 and 3, slots 40, 42, 44 and 46 are formed in breakaway post 30 at a location corresponding approximately with the anticipated ground line when breakaway support post 30 is properly installed adjacent to the associated.roadway.
For one application, elongated body 32 may be formed from a standard steel I-beam with flanges 36 and 38 having a nominal width of four (4") inches and web 34 having a nominal width of six (6") inches. Slots 40, 42, 44 and 46 have a generally elongated oval configuration approximately six (6") inches in length and one fourth (1/4") inch in width. Slots 40, 42, 44, and 46 are positioned intermediate ends 31 and 33 to cause local buckling of the associated breakaway post 30 when properly installed.
For the embodiments shown in FIGURES 1 and 2, block 48 is disposed between breakaway support post 30 and guardrail 22. Block-48 may sometimes be referred to as a "blockout."
For other applications, guardrail 22 may be directly mounted adjacent to end 31 of breakaway support post 30.
During a rail face impact between a vehicle and guardrail 5 22 downstream from th.e associated end treatment, block 48 provides a lateral offset between breakaway support post 30 and guardrail 22. The distance and direction of the lateral offset is selected to prevent the wheels (not shown) of an impact~_ng vehicle from striking breakaway 10 support post 30 during the rail face impact.
For the embodiment shown in FIGURES 1, 2 and 3, breakaway support po~;t 30 includes soil plates 52 and 54 which are attached to the exterior of respective flanges 36 and 38 adjacent to the portion of breakaway support post 30 15 which will be inserted into the soil adjacent to the associated roadway. For this embodiment, soil plates 52 and 54 have approximately the same thickness as web 34 and are generally ~iligne~~ with web 34 on opposite sides of respective flanges 36 and 38.
Breakaway support: post 30 is preferably installed with web 34 extended approximately perpendicular from guardrail 22 and flanges 36 and 38 extending generally parallel with guardrail 22. By aligning web 34 approximately perpendicular t~o guardrail 22, breakaway support post 30 will provide sufficient support to resist large forces associated with a rail face impact or rail face impact between a vehicle and guardrail 22. As a result of forming slots 40, 42, 44 and 46 in respective flanges 36 and 38 and orienting flan~~es 36 and 38 generally parallel with guardrail 22, a head-on impact from a vehicle with one end of guardrail 22 will result in buckling or yielding of breakaway support post 30.
The amount of force required to buckle and/or fracture breakaway support po:>t 30 may be decreased by increasing the size and/o:r the number of slots 40, 42, 44 and 46 formed in -respective flanges 36 and 38. Alternatively, reducing the number and/or size of slots 40, 42, 44 and 46 will result in a larger amount of force required to buckle or yield breakaway support post 30. -The orientation of soil plates 52 and 54, relative to a head-on impact with one end of guardrail 22 will prevent twisting or tilting of breakaway support post 30 during the head-on impact. The additional support provided by soil plates 52 and 54 will increase the reliability of breakaway support post 30 yielding or buckling at the general location of slots 40, 42, 44 and 46 in response to a selected amount of force applied adjacent to end 31 of post 30 in a first direction corresponding to the direction of a head-on impact with one end of guardrail 22. Soil plate 52 includes a generally triangular portion 56 which extends above elongated slots 40, 42, 44 and 46 to provide additional support for breakaway support post 30 and guardrail 22 during a rail face impact.
For some applications, the length of elongated body 32 may be increased such that soil plates 52 and 54 are no longer required to provide additional support for the resulting breakaway support post 30. Eliminating soil plates 52 and 54 will allow a hydraulic or pneumatic hammer to more quickly install the associated breakaway support post 30 and a crane or hydraulic/ pneumatic pulling tool to more easily remove a damaged breakaway support post 30.
Alternatively, breakaway support post 30 could be inserted into an appropriately sized concrete foundation and/or metal sleeve. Soil plates, concrete foundation, sleeves and other anchoring devices can be used in any of the posts of the present invention.
For some applications, it may be preferable to form a breakaway support post in accordance with teachings of the present invention from an elongated body having a generally hollow, rectangular or square configuration (not shown).

Slots 40, -42, ~:4 and 46 may then be formed in opposite sides of the resulting breakaway support post which are aligned general:Ly parallel with the associated guardrail similar to flanges 36 and 38. The other pair of opposite sides preferably extend approximately normal from the associated guardrail similar to web 34.
When force is applied adjacent to end 31 of breakaway support post 30 in a ~;econd direction corresponding with a rail face impact between a vehicle and guardrail 22, web 34 will resist buckling of breakaway support post 30 and provide sufficient support to redirect the impacting vehicle back onto the roadway.
Breakaway :>upport post 130, as shown in FIGURES 4, 5 and 6, includes elongated body 132 having an upper portion 142 and a lower portion 144 which are rotatably coupled with each other, i~or the embodiment of the present invention shown in FIGURES 4, 5 and 6, rotatable coupling assembly 140 is preferably installed intermediate ends 131 and 133 of elongated body 132. Upper portion 142 and lower portion 144 each have a general configuration of an I-beam defined in part by re~cpective webs 134 and flanges 136 and 138. Upper portion 142 and lower portion 144 may be formed from a conventional steel I-beam in the same manner as previously described.
For the embodiment of the present invention as shown in FIGURES 4, ~ and 6, rotatable coupling assembly 140 includes a first generally U-shaped bracket 150 attached to one end of upper portion 142, opposite end 131 and a second U-shaped bracket= 152 attached to the end of lower portion 144 opposite from end 133. Brackets 150 and 152 each have a generally open, U-ahaped configuration. A portion of bracket 150 is preferably sized to fit within a corresponding portion of bracket 152. Pivot pin 154 extends laterally through adjacent portions of bracket 150 and 152 in a direction which is generally parallel with webs 134.- The resulting breakaway support post 130 is preferably installed with webs 134 and pivot pin 154 extending generally normal from the associated guardrail 22. As a result of this orientation, webs 134 and rotatable coupling assembly 140 including pivot pin 154 allow breakaway support post 130 to sufficiently support guardrail 22 during a rail face impact to redirect an impacting vehicle back onto the associated roadway.
In FIGURES 4, 5 and 6, respective webs 134 of upper portion 142 and lower portion 144 are shown generally aligned parallel with each other. For some applications, the orientation of lower portion 144 may be varied with respect to upper portion 142 such that web 134 of lower portion 144 extends approximately parallel with guardrail 22. The attachment of brackets 150 and 152 with their respective upper portion 142 and lower portion 144 may be modified to accommodate various orientations of lower portion 144 relative to upper portion 142.
Depending upon the length of lower portion 144 and the type of soil conditions, soil plates 162 and 164 may be attached to lower portion 144 extending from respective flanges 136 and 138. For some applications, lower portion 144 may be substantially longer than upper portion 142. As a result of increasing the length of lower portion 144, the use of soil plates 162 and 164 may not be required.
Shear pin 156 is laterally inserted through adjacent portions of brackets 150 and 152 offset from pivot pin 154.
Shear pin 156 preferably has a relatively small cross-section as compared to pivot pin 154. As a result, when a vehicle impacts with one end of guardrail 22, shear pin 156 will break and allow upper portion 142 to rotate relative to lower portion 144 as shown in FIGURE 6. Shear pin 156 maintains upper portion 142 and lower portion 144 generally aligned with each other during installation of the associated breakaway support post 30.

The amount of force required to fracture or break shear pin 156 may be determined by a variety of parameters such as the diameter of shear pin 156, the type of material used to fabricate shear pin 156, the number of locations (either along a single pin or with plural pins) that must be sheared, and the distance between shear pin 156 and pivot pin 154. As discussed later in more detail with respect to breakaway ~;upport post 530, as shown in FIGURES
15A through 16, rotatable coupling 540 may be modified to allow upper portion !~42 to disconnect and separate from lower portion 59:4.
Various types of releasing mechanisms other than shear pin 156 may be satisfactorily used to maintain upper portion 142 and lower portion 144 generally aligned with each other during normal installation and use of the associated brea~~away support post 130. A wide variety of shear bolts, shear screws and/or breakaway clamps may be used to releasably ai~tach first bracket 150 with second bracket 152.
When a veh_~cle impacts with one end of guardrail 22, force is applied in a first direction to upper portion 142 and will break ;shear pin 156. As a result, upper portion 142 will then rotate relative to lower portion 144 as shown in FIGURE 6.
FIGURES 7, 8 and 9 show portions of highway guardrail system 220 which includes breakaway support post 230 and guardrail 22. Breakaway support post 230 includes elongated body 32 and is similar in both design and function with breakaway support post 30. One difference between breakacaay support posts 30 and 230 is the replacement of s~~il plates 52 and 54 by soil plates 254 and 256. As best shown in FIGURES 8 and 9, fastener assembly 160 may be used. to attach soil plate 254 with elongated body 32. Fastener assembly 160 includes threaded bolt 162, hollow sleeve o:r spacer 168 and nut 164. The use of soil plate 254 and fastener assembly 160 eliminates some of the welding steps associated with attaching soil plates 52 and 54 to breakaway support post 30.
Soil plate 254 has a generally rectangular 5 configuration. The length, width and thickness of soil plates 254 may be varied depending upon the intended application for the associated breakaway post 230 and the anticipated soil conditions adjacent to the associated roadway. An appropriately sized hole is preferably formed 10 in the mid-point of soil plate 254 and bolt 162 inserted therethrough. The head 166 of bolt 162 is disposed on the exterior of soil plate 254. Spacer or hollow sleeve 168 is then fitted over the threaded portion of bolt 162 extending from soil plate 254 opposite from head 166. A
15 corresponding hole is preferably formed in web 34 at the desired location for soil plate 254. Bolt 162 is inserted through the hole in web 34 and nut 164 attached thereto.
For some applications, a smaller soil plate 256 may be attached to the exterior of flange 36 adjacent to web 34.
20 The dimensions and location of soil plate 256 may be varied depending upon the anticipated application including soil conditions, associated with highway guardrail system 220.
FIGURES 10 and 11 illustrate portions of highway guardrail system 320, which includes breakaway support post 330 and guardrail 22. FIGURE 11 illustrates an embodiment of support post 330 having narrower breaker bars 350 and 352 than those illustrated in FIGURE 10. Support post 330 includes an elongated body 332 having an upper portion 342 and a lower portion 344. Upper portion 342 and lower portion 344 each have the general configuration of a steel I-beam similar to elongated body 32 of breakaway support post 30.
Upper portion 342 and lower portion 344 are defined in part by respective webs 334 and flanges 336 and 338. Upper portion 342 and lower portion 344 may be formed from a conventional steel I-beam in the same manner as previously described. Lower portion 344 may be positioned substantially within the ground. Alternatively, lower portion 344 coL.ld be inserted into a concrete foundation and/or a metal :sleeve which have been previously installed at the desired :roadside location.
Upper portion 392 and lower portion 344 are provided with breaker bans 350 and 352. In the embodiment shown in FIGURE 10, flanges 336 and 338 in upper portion 342 are connected to ~~reaker bar 350, by for example, welds.
Flanges.336 and 338 in lower portion 344 may be connected to breaker bar 352 in an analogous fashion. Other suitable connection techniques may be used to couple flanges 336 and 338 of upper and. lower portions 342 and 344 to breaker bars 350 and 352, respectively. For example, as illustrated in FIGURE 11, tie straps 362 and 364 may be used, particularly in an embodiment where breaker bars 350 and 352 are narrower than flanges 336 and 338, as is the case in FIGURE
11. For some a~~plicat:ions, breaker bar 352 may be directly attached to a concrete foundation to eliminate the use of lower portion 344.
Breaker bars 350 and 352 are connected to each other by fasteners 358, whi~~h is illustrated by a simple nut and bolts however, other suitable fasteners may be used with this aspect of the invention. Breaker bars 350 and 352 are preferably formed with chamfered or tapered surfaces 354.
Chamfered surfaces 354 cooperate with each other to define in part a notch or ga~> between adjacent portions of breaker bars 350 and 352.. Chamfered surfaces 354 extend generally parallel with each other in a direction generally normal to guardrail 22. An imaginary line 359 can also be drawn through fasteners 358 in the same general direction parallel with chamfered surfaces 354 and normal to guardrail 22. Imaginary line 359 corresponds with a strong direction for breakaway support posts 230 in which breakaway -support post 230 exhibits high mechanical strength. There is a notch or gap on each side of the imaginary line 359.
Chamfered surfaces 354 cooperate with each other to allow upper portion 342 to pivot relative to lower portion 344 during a head-on impact, as illustrated in FIGURE 11.
Such pivoting may cause fasteners 358 to break, separating upper portion 342 from lower portion 344 and may therefore substantially minimize damage to a vehicle during a head-on impact with the end of guardrail 22 facing oncoming traffic. The orientation of chamfered surfaces 354 and fasteners 358 relative to each other further define a weak direction for breakaway support post 330 in which support post 330 exhibits low mechanical strength. However, chamfered surfaces 354 do not reduce the ability of guardrail 320 to redirect an impacting vehicle back onto the associated roadway during a rail face impact with guardrail 22.
FIGURE 12 is a schematic drawing showing an exploded isometric view with portions broken away of an alternative embodiment of breaker bars suitable for use in guardrail system 320. Breaker bars 450 and 452 perform similar functions as breaker bars 350 and 352. Breaker bar 450 includes a flat plate 453 having a protruding member or projection 454. Breaker bar 452 includes a flat plate 455 having a protruding member or projection 456. Flat plates 453 and 455 are each formed with two or more apertures 458 for receiving a connecting member, such as mechanical fastener 358, for attaching breaker bars 450 and 452 with each other. The use of protruding members or projections 454 and 456 allows upper portion 342 to pivot relative to lower portion 344 during a head-on impact, as illustrated in FIGURE 13. Impact from the weak direction for support post 330 will result in bending and preferably failure of connecting members 358: Failure of connecting members 358 separates upper ~~ortio:n 342 from lower portion 344 and may, therefore, substantially minimize damage to a vehicle during a head-on impact with the end of guardrail 22 facing oncoming traffic. However, protruding members or projections 454 and 456 do not reduce the ability of guardrail 22 to redire~~t an impacting vehicle back onto the associated road~ray during a rail face impact.
FIGURES 14A anc'. 14B are schematic drawings with portions broken away .showing an alternative embodiment of a frangible or yie7.dable connection satisfactory for releasably coup:Ling upper portion 342 with lower portion 344 of support pest 330. For this embodiment, breaker bars 450 and 452 are substantially the same as previously described with respect to the embodiment shown in FIGURE
13, except for the elimination of protruding members or projections 454 and 956. A pair of elongated connecting members 458 anci a plurality of nuts 460 are preferably provided to maintain a desired gap or spacing between breaker bars 450 and 452. For the embodiment shown in FIGURES 14A and 14B, elongated connecting members 458 and nuts 460 have matchincr threads. However, various types of mechanical fasteners and connecting members may be satisfactorily used to position upper portion 332 of support post 330 relai=ive to lower portion 344.
As a results of incorporated teachings of the present invention, support post 330 has relatively low mechanical strength with respect to impact from a direction generally normal to an imaginary line 359 (see FIGURE 10) extending through connecting members 358 or 458 as appropriate. This direction may he rej_erred to as the "weak direction."
Connecting membE~rs 358 and 458 are preferably formed from materials which will yield and preferably fracture or break to allow upper abortion 342 to separate from lower portion 344. Since there is a gap between the breaker bars 350 and 352 or breaker tars 4~>0 and 452 to either side of line 359 in the wea~C direction, connecting members 358 or 458 as appropriate will carry substantially all of the force or load from an impact in the weak direction.
When support post 330 is impacted from another direction, the resulting force, or at least a component of the resulting force, will tend to place one of the associated connecting members 358 or 458 as appropriate in tension, and will tend to place the other connecting member 358 or 458 as appropriate in compression. Therefore, the mechanical strength of the frangible connection between upper portion 342 and lower portion 344 is substantially greater in the strong direction as compared with an impact from the weak direction. The strongest direction for an impact with support post 330 is from a direction substantially perpendicular to the surface of flanges 338 and 336 and parallel with web 334 (the strong direction).
The weakest direction for an impact with support post 330 is in a direction which is substantially perpendicular to web 334 and parallel with flanges 336 and 338.
Spacers with various forms and configurations may be used to separate breaker bars 350 and 352 or 450 and 452 from each other as desired. For the embodiment shown in FIGURES 10 and 11, tapered surfaces or chamfered surfaces 354 form the necessary spacers as integral components of breaker bars 350 and 352. For the embodiment shown in FIGURES 12 and 13, protruding members or projections 454 and 456 function as spacers to form the desired gap. For the embodiment shown in FIGURES 14A and 14B, nuts 460 cooperate with connecting members 458 to function as spacers to form the desired gap. Nuts 460 that are between breaker bars 450 and 452 may also be referred to as "stops."
For some applications, upper portion 342 and lower portion 344 of support post 330 may be coupled with each other by only one connecting member 358 or 458.

Alternative-ly, more than two connecting members 358 or 458 may be used depending upon the anticipated application for the associated ;support post 330. For some applications, one connecting member 358 or 458 may be provided- on the 5 side of support post 330 which is immediately adjacent to guardrail 22. The associated breaker bars 350 and 352 or 450 and 452 will contact each other on the opposite side of the post, whereby the single connecting member 358 or 458 as appropriate will provide sufficient strength for support 10 post 330 to withstand rail face or side impact with the associated guard rail 22.
Support post 530, as shown in FIGURES 15A through 16, is substantially similar to previously described support post 130, except. rotatable coupling assembly 140 has been 15 replaced by rotai=able coupling assembly or releasable hinge 540. The embodiment shown in FIGURES 15A, 15B, 15C and 16 provides for the separation of upper portion 142 from lower portion I44. Thus, upper portion 142 will not lift an impacting vehicle. Support post 530 may be formed in part 20 by upper portion 142 and lower portion 144 as previously described with respect to support post 130. Coupling assembly or releasable hinge 540 preferably includes a first generally ZJ-shaped bracket 550 attached to one end of upper portion :142, .and a second U-shaped bracket 552 25 attached to an adjacent end of lower portion 144. Brackets 550 and 552 each have a generally open, U-shaped configuration. A portion of bracket 550 is preferably sized to fit ovE~r a corresponding portion of bracket 552.
Pivot pin 554 preferably extends through adjacent portions of brackets 'i52 in a direction which is generally parallel with webs 134. Alternatively, pivot pin 554 may be replaced by generally round projections extending from opposite sides of bracket 552. Bracket 550 preferably includes a pail- of slots 572 formed in opposite sides thereof. -Slots 572 are preferably sized to releasably engage respective portions of pin 554 which extend from bracket 552. Slots 572 cooperate with pivot pin 554 to allow rotation of upper portion 142 relative to lower portion 144, and to allow disengagement of upper portion 142 from lower portion 144.
The resulting breakaway support post 530 is preferably installed with webs 134 and pivot pin 554 extending generally normal from the associated guardrail 22. As a result of this orientation, webs 134 and releasable hinge 540, including pivot pin 554, allow support post 530 to adequately support guardrail 22 during a rail face impact to redirect an impacting vehicle back onto the associated roadway.
Shear pin 556 is preferably inserted through adjacent portions of brackets 550 and 552 offset from pivot pin 554.
Shear pin 556 maintains upper portion 142 and lower portion 144 generally aligned with each other during installation of the associated breakaway support post 530. Shear pin 556 preferably has a relatively small cross-section as compared to pivot pin 554. As a result, when a vehicle impacts with one end of guardrail 22, shear pin 556 will break and allow upper portion 142 to rotate relative to lower portion 144 as shown in FIGURE 16.. For some applications, push bar 580 is preferably attached to and extends between opposite sides of bracket 552. The location of push bar 580 on bracket 552 is selected to assist disengagement of slot 572 from pivot pin 554 as upper portion 142 rotates relative to lower portion 144.
See FIGURE 16.
The amount of force required to fracture or break shear pin 556 may be determined by a variety of parameters such as the diameter of shear pin 556, the type of material used to fabricate shear pin 556, the number of locations (either along a single pin or with plural pins) that must be sheared-, anc3 the distance between shear pin 556 and pivot pin 554.
Various ty~~es of releasing mechanisms other than shear pin 556 may be satisfactorily used to maintain upper portion 142 and. lower portion 144 generally aligned with each other during normal installation and use of the associated breakaway support 530. A wide variety of shear bolts, shear screws, frangible disks, and/or breakaway clamps may be used to releasably attach first bracket 550 with second bracket 552.
When a vehicle impacts with one end of guardrail 22, force is applied in a. first direction (weak direction) to upper portion L42 and will break shear pin 556. As a result, upper abortion 142 will then rotate relative to lower portion 19:4 as shown in FIGURE 16. When portions of bracket 550 contact push bar 580, slots 572 will disengage from pivot pin 554 and. release upper portion 142 from lower portion 144.
Although the pre~~ent invention and its advantages have been described in detail it should be understood that various changes, substitutions, and alterations can be made hereto without departing from the spirit and scope of the invention as de:Eined :by the following claims.

Claims (41)

CLAIMS:

1. A roadway guardrail system, comprising:
a guardrail;
at least one support post having an upper portion and a lower portion, the upper portion having a lower end and the lower portion having an upper end;
the upper portion being coupled to the guardrail and the lower portion being structured and arranged to be located in the earth;
the upper portion lower end comprising a first member and the lower portion upper end comprising a second member;
the first and second members being coupled together with at least two rods, the rods laying along an imaginary line that extends in a strong direction, wherein the post exhibits a high mechanical strength in the strong direction, there being a weak direction that is generally perpendicular to the strong direction, wherein the support post exhibits a low mechanical strength in the weak direction;
at least one spacer located between the first and second members, there being a gap on at least one side of the imaginary line, wherein the upper portion can rotate relative to the lower portion in the weak direction when subjected to a force; and the upper and lower portions comprise I-beams, each of the I-beam portions having a web, with the web of the upper portion being generally aligned with the web of the lower portion, and with the imaginary line extending generally in the same direction as the webs.

2. A roadway guardrail system, comprising:
a guardrail;

at least one support post having an upper portion and a lower portion, the upper portion having a lower end and the lower portion having an upper end;
the upper portion being coupled to the guardrail and the lower portion being structured and arranged to be located in the earth;
the upper portion lower end comprising a first member and the lower portion upper end comprising a second member;
the first and second members being coupled together with at least two rods, the rods laying along an imaginary line that extends in a strong direction, wherein the post exhibits a high mechanical strength in the strong direction, there being a weak direction that is generally perpendicular to the strong direction, wherein the support post exhibits a low mechanical strength in the weak direction;
at least one spacer located between the first and second members, there being a gap on at least one side of the imaginary line, wherein the upper portion can rotate relative to the lower portion in the weak direction when subjected to a force; and the spacer comprises a projection that extends from one of the first and second members and that bears on the other of the first and second members.

3. A roadway guardrail system, comprising:
a guardrail;
at least one support post having an upper portion and a lower portion, the upper portion having a lower end and the lower portion having an upper end;
the upper portion being coupled to the guardrail and the lower portion being structured and arranged to be located in the earth;

the upper portion lower end comprising a first member and the lower portion upper end comprising a second member;
the first and second members being coupled together with at least two rods, the rods laying along an imaginary line that extends in a strong direction, wherein the post exhibits a high mechanical strength in the strong direction, there being a weak direction that is generally perpendicular to the strong direction, wherein the support post exhibits a low mechanical strength in the weak direction;
at least one spacer located between the first and second members, there being a gap on at least one side of the imaginary line, wherein the upper portion can rotate relative to the lower portion in the weak direction when subjected to a force; and the spacer comprises two projections, with each projection extending from a respective one of the first and second members, the projections generally bearing on each other.

4. The roadway guardrail system of claim 1, further comprising:
the rods are bolts secured by nuts;
the first and second members each comprise flanges that extend transversely from a longitudinal axis of the respective upper and lower portions; and the spacer comprises a projection that extends from one of the first and second members and that bears on the other of the first and second members.

5. The roadway guardrail system of claim 1, wherein:
the rods are bolts secured by nuts;

the first and second members each comprise flanges that extend transversely from a longitudinal axis of the respective upper and lower portions; and the spacer comprises stops located on the rods.

6. A breakaway support post for mounting a guardrail thereon as part of a highway guardrail system comprising:
an elongated body having an upper portion and a lower portion;
a rotatable coupling assembly disposed between the upper portion and the lower portion of the elongated body;
the upper portion of the elongated body having a first end;
the lower portion of the elongated body having a second end which may be inserted into the soil adjacent to a roadway;
means for attaching the guardrail adjacent to the first end of the upper portion; and means for releasably securing the upper portion of the elongated body in a generally collinear alignment with the lower portion of the elongated body such that an impact with one end of the attached guardrail will tend to rotate the upper portion of the elongated body relative to the lower portion of the elongated body and the breakaway support post will resist a rail face impact with the guardrail.

7. The breakaway support post of claim 6 wherein the rotatable coupling further comprises:
a first U-shaped bracket and a second U-shaped bracket with portions of the first bracket disposed within the second bracket; and a pivot pin extending laterally through adjacent portions of the first bracket and the second bracket whereby the upper portion of the elongate body may rotate relative to the lower portion of the elongated body.

8. The breakaway support post of claim 6 wherein the upper portion of the elongated body and the lower portion of the elongated body further comprise:
a metal I-beam having a web with a pair of flanges attached thereto;
a respective bracket attached to adjacent ends of the upper portion and the lower portion; and a pivot pin extending through the brackets and aligned approximately parallel with the web of the upper portion whereby the breakaway support post will resist a rail face impact with the guardrail.

9. The breakaway support post of claim 6 further comprising a block affixed to the upper portion of the elongated body and adapted for mounting the guardrail to form a lateral offset between the guardrail and the breakaway support post.

10. A breakaway support post for mounting a guardrail thereon as part of a highway guardrail system comprising:
an elongated body having an upper portion and a lower portion;
the upper portion of the elongated body having a first end;
the lower portion of the elongated body having a second end;
means for attaching the guardrail adjacent to the upper portion; and '~ 33 means for coupling the first end of the elongated body with the second end of the elongated body such that an impact with one end of the attached guardrail will tend to rotate the upper portion of the elongated body relative to the lower portion of the elongated body and the breakaway support post will resist a rail face impact with the guardrail.

11. The breakaway support post of claim 10 wherein the means for coupling the first end with the second end comprises first and second breaker bars.

12. The breakaway support post of claim 11 wherein the first and second breaker bars are formed with respective chambered surfaces to facilitate rotation of the upper portion relative to the lower portion and to facilitate separation of the upper portion of the elongated body from the lower portion of the elongated body.

13. The breakaway support post of claim 11 wherein the first and second breaker bars further comprising protruding members to facilitate rotation of the upper portion relative to the lower portion and to facilitate separation of the upper portion of the elongated body from the lower portion of the elongated body.

14. A roadway guardrail system comprising:
a guardrail;
at least one support post having an upper portion and a lower portion, the upper portion having a lower end and the lower portion having an upper end;
the upper portion being coupled to the guardrail and the lower portion being insertable into the earth;

the upper portion lower end being pivotally coupled to the lower portion upper end by a hinge, the hinge having a pivot pin that extends in a strong direction which is substantially perpendicular to the guardrail, wherein the post exhibits a high mechanical strength in the strong direction, the hinge having a weak direction that is generally perpendicular to the strong direction, wherein the upper portion can rotate relative to the lower direction from an impact in the weak direction; and the hinge is releasably restrained from pivoting by a shear pin, the shear pin being smaller in diameter than the pivot pin.

15. The roadway guardrail system of claim 14 wherein the upper and lower portions each comprise an I-beam having a web and flanges, the webs of the I-beams being oriented generally perpendicular to the guardrail.

16. The roadway guardrail system of claim 14 wherein the hinge comprises:
a first U-shaped bracket and a second U-shaped bracket with portions of the first bracket being disposed within the second bracket; and the pivot pin extending laterally through the first bracket and through adjacent portions of the first bracket and the second bracket whereby the upper portion of the post can rotate relative to the lower portion of the post.

17. The roadway guardrail system of claim 14 wherein the hinge has a first bracket coupled to the upper portion and a second bracket coupled to the lower portion, the first bracket receiving the pivot pin by a slot, the slot being oriented so that when the upper portion is rotated relative to the lower portion, the upper portion can separate from the lower portion.

18. A support post for mounting a guardrail thereon as part of a highway guardrail system, comprising:
a first elongated member having first and second ends, with the first end of the first member adapted to receive a guardrail;
a second elongated member having first and second ends, with the first end of the second member being insertable into the ground adjacent to a roadway;
one of the second ends having a first bracket with a generally U-shaped configuration extending therefrom;
the other of the second ends having a second bracket extending therefrom;
the second bracket being received in the first U-shaped bracket;
the first and second brackets being coupled together by a pin extending along an axis substantially perpendicular to a received guardrail, wherein the first and second members are rotatably coupled; and the first and second members being maintained in a first position by a shearable body extending between the second bracket and at least a portion of the first U-shaped bracket.

19. A support post for mounting to a guardrail as part of a highway guardrail system, comprising:
a first I-beam having first and second ends, with the first end of the first I-beam being structured and arranged to couple to the guardrail;
a second I-beam having first and second ends, with the first end of the second I-beam being insertable into the ground adjacent to a roadway;

each of the first and second I-beams having a web and flanges, with the flanges at the respective second ends having extensions protruding beyond the web;
the extensions of the first I-beam being located adjacent to the extensions of the second I-beam, the extensions of the first and second I-beams being pivotally coupled together by a hinge pin so that the first and second I-beams pivot about an axis that is parallel to the web of the first I-beam between a lengthened, substantially collinear position and a non-collinear position; and the first and second I-beams being maintained in the lengthened position by a shearable member extending between at least one of the extensions of the first I-beam and at least one of the extensions of the second I-beam.

20. A roadway guardrail system, comprising:
a guardrail;
at least one support post having an upper portion and a lower portion, the upper portion having a lower end and the lower portion having an upper end;
the upper portion being coupled to the guardrail and the lower portion being insertable into the earth;
the lower end of the upper portion being coupled at the upper end to the lower portion by a rotatable coupling that rotates about an axis when the post is impacted in a direction that is generally parallel to the guardrail, the axis being substantially perpendicular to the guardrail, the post exhibiting a high mechanical strength in the direction of the axis; and the rotatable coupling having a frangible connection for maintaining the upper portion in an upright alignment with respect to the lower portion.

21. A breakaway guardrail post for highway crash control systems comprising:
an upper post member having a weak impact axis and a strong impact axis;
a lower post member disposed beneath and spaced apart from said upper post member;
a connecting joint member having a first end and a second end, said first end of said joint member connected at said first end by a first fastener to said upper post member and connected at said second end by an attachment to said lower post member, said first fastener having a first failure strength less than a second failure strength of said attachment;
said first fastener having a first connector having a first failure strength and a second connector having a second failure strength; and said first failure strength greater than said second failure strength such that upon an impact force being applied along said weak impact axis, said second connector fails and said upper post member rotates about said first connector.

22. A roadway guardrail system comprising:
a guardrail;
at least one support post coupled to said guardrail and comprising an elongate body having a first portion and a second portion arranged in a substantially collinear relationship;
a frangible connection for coupling the first portion with the second portion, the frangible connection including a rotatable coupling assembly disposed between the first portion and the second portion of the elongate body; and the frangible connection being oriented relative to the guardrail such that an impact with one end of the guardrail coupled to the support post will tend to buckle the support post and such that the support post will resist an impact with a rail face of the guardrail.

23. A breakaway guardrail post for highway crash control systems comprising:
an upper post member having a weak impact axis and a strong impact axis;
a lower post member disposed beneath and spaced apart from said upper post member;
a connecting joint member having a first end and a second end, said first end of said joint member connected at said first end by a first fastener to said upper post member and connected at said second end by a second fastener to said lower post member, said first fastener having a first failure strength less than a second failure strength of said second fastener;
said first fastener having a first connector having a first failure strength and a second connector having a second failure strength; and said first failure strength greater than said second failure strength such that upon an impact force being applied along said weak impact axis, said second connector fails and said upper post member rotates about said first connector.

24. A breakaway support post for mounting a guardrail thereon as part of a highway guardrail system disposed adjacent to a roadway comprising:
an elongated body which resists impact by a motor vehicle from a strong direction and yields to impact by the motor vehicle from a weak direction;

the weak direction and the strong direction disposed substantially perpendicular to each other;
the elongated body having a first end and a second end;
the elongated body having a cross section operable to be oriented with respect to an attached guardrail, the cross section having a low mechanical strength in the weak direction whereby an impact from the weak direction with one end of an attached guardrail, which is substantially parallel to said weak direction, will tend to buckle the breakaway support post;
the cross section further operable to be oriented with respect to the attached guardrail to resist an impact in the strong direction and the elongated body operable to be driven directly into the soil adjacent to the roadway.

25. The breakaway support post of claim 24 wherein the elongated body further comprises:
an I-beam having a web with a pair of flanges attached thereto; and multiple openings formed in the flanges of the I-beam.

26. The breakaway support post of claim 24 further comprising means for attaching a block between the first end of the elongated body and a guardrail to form a lateral offset between the guardrail and the breakaway support post.

27. The breakaway support post of claim 24 further comprising at least one soil plate attached to the elongated body.

28. A breakaway support post for mounting a guardrail thereon as part of a highway guardrail system comprising:
an elongated body operable to resist an impact by a motor vehicle from a strong direction and operable to yield in response to an impact by a motor vehicle from a weak direction;
the weak direction and the strong direction disposed substantially normal to each other;
the weak direction oriented generally parallel with an attached guardrail;
the strong direction oriented generally perpendicular with an attached guardrail;
means for attaching a guardrail adjacent to the first end of the elongated body;
a plurality of openings formed in the elongated body intermediate the first end and the second end, the plurailty of openings located in a plane that is generally parallel to the attached guardrail; and the elongated body having a cross section operable to be oriented with respect to the attached guardrail whereby an impact from the weak direction with one end of the attached guardrail will tend to buckle the breakaway support post proximate the openings and the breakaway support post will resist a rail face impact with the guardrail from the strong direction.

29. A roadway guardrail system, comprising:
a guardrail;
at least one support post defined in part by an I-beam having a web and flange, wherein the flanges are formed at each end of the web and extend perpendicular from the end of the web such that the I-beam forms an I
shape;
the support post having a first end and a second end;
the first end coupled to the guardrail by way of one of the flanges and the second end operable to be located in the earth;
each flange having at least one opening formed therein and disposed near the surface of the earth when the support post is located in the earth; and the openings defining in part a frangible connection between the first and second end of the support post whereby an impact with one end of an attached guardrail will tend to buckle the support post and the support post will resist a rail face impact with an attached guardrail.

30. The system of claim 29 wherein the openings comprise vertical slots.

31. The system of claim 29 further comprising the support post operable to be directly driven into soil adjacent to a roadway.

32. A support post for mounting a guardrail thereon as part of a highway guardrail system comprising:
an elongated body having a first portion defining a first end of the elongated body and a second portion defining a second end of the elongated body;

a frangible connection coupling the first portion with the second portion;
the frangible connection operable to be oriented generally parallel to an attached guardrail and in such orientation having a low mechanical strength such that an impact with one end of the attached guardrail will tend to buckle the support post; and the frangible connection operable to be oriented relative to the guardrail such that the support post will resist a rail face impact with the attached guardrail.

33. The support post of claim 32 wherein the frangible connection further comprises a plurality of openings formed in the elongated body.

34. A roadway guardrail system, comprising:
a guardrail;
at least one support post, the support post comprising an I-beam having a web and flanges, wherein the flanges are formed at each end of the web and extend perpendicular from the end of the web such that the I-beam forms an I shape;
the support post having a first end and a second end, the first end being coupled to the guardrail and the second end being structured and arranged to be located in the earth; and the flanges having vertical slots therein located near the surface of the earth when the support post is located in the earth.

35. A support post for mounting a guardrail thereon as part of a highway guardrail system comprising:

an elongated body having a first portion and a second portion;
a frangible connection for coupling the first portion with the second portion; and the frangible connection operable to be oriented generally parallel to the guardrail and in such orientation having a low mechanical strength whereby an impact with one end of the guardrail will tend to buckle the support post and the support post will resist a rail face impact with the guardrail.

36. The support post of claim 35 further comprising:
the elongated body having a first end and a second end; and a plurality of openings formed in the elongated body intermediate the first end and the second end to define in part the frangible connection.

37. A breakaway support post for mounting a guardrail thereon as part of a highway guardrail system comprising;
an elongated body defined in part by an I-beam having a web and flanges, wherein the flanges are formed at each end of the web and extend perpendicular from the end of the web such that the I-beam forms an I shape;
the support posts having a first end and a second end;
the first end operable to be coupled to a guardrail and the second end operable to be located in the earth adjacent to a roadway;

each flange having at least one opening formed therein and disposed near the surface of the earth when the support post is located in the earth; and the openings in the flanges cooperating with each other to allow an impact by a vehicle with one end of an attached guardrail to buckle the support post and to allow the support post to resist a rail face impact by a vehicle with an attached guardrail.

38. The breakaway support post of claim 37 wherein the openings comprise vertical slots.

39. The breakaway support post of claim 25 wherein the openings are located so as to be above and near the soil when the post is located in the soil.

40. The breakaway support post of claim 25 wherein the multiple openings further comprise at least four openings, with each flange having at least two openings, with the respective two openings being on opposite sides of the web.

41. The breakaway support post of claim 25 further comprising means for attaching a block between the first end of the elongated body and a guardrail to form a lateral offset between the guardrail and the breakaway support post.