Algorithm to identify axle weights for an innovative BWIM system- Part I

Transcription

1 ABSE-JSE Jon onference on Advances n Brdge Engneerng- Augus 8- Dhaa Bangladesh. SB: An u Bhuyan eds. Algorh o denfy axle weghs for an nnovave B syse- ar Hua Zhao School of vl Engneerng Hunan Unversy hangsha Hunan hna 48 as Uddn Deparen of vl onsrucon and Envronenal Engneerng Unversy of Alabaa a Brngha Alabaa USA ABSTAT: Ths paper nroduces an nnovave brdge wegh-n-oon B syse whch uses nsruened brdge as a large scale o connuously collec vehcle nforaon of passng vehcles ncludng speed axle spacng and axle weghs. Based on feld es on he brdge on hghway -78 n Alabaa hs paper proposes an algorh for he B syse o denfy he axle weghs of heavy vehcles on hghways. The B syse aes he nfluence lne as a reference o calculae axle weghs. A frs he algorh for calculaon s proposed based on connuously easured brdge response sran of wo calbraon vehcles 5-axle se-raler of nown weghs and axle spacng runnng any es across he nsruened brdge. Then he research heren proposes a odfed oses algorh based on he calculaed o calculae axle weghs n ers of he leas square ehods wh nzaon he dfferences beween easured brdge response bendng oens and predced ones a d span when he vehcle passes he brdge. The aheacal equaons o calculae he and axle weghs are derved and he proposed algorh s pleened by copuer progra n ATAB. Feld esng of a concree slab-grder brdge on hghway -78 n Alabaa n he U.S. s pleened o es and evaluae he accuracy of he proposed algorh n he denfcaon of he axle weghs wh he coparson of sac weghs and ha fro bendng plae B syse of ovng heavy vehcles. Tes resuls shows ha B syse exhbs advanages over B syse n acqurng acual lve load daa owng o s accuracy porably and cos-effecveness. TDUT n he U.S. abou half of he 6 hghway brdges were bul before 94 whch eans ha hey are on average abou 6 years old. Soe 4% of he brdges are consdered defecve and are elgble canddaes for hghway brdge replaceen and rehablaon progra. ne of he crucal facors o opze safey evaluaon of exsng old and defcen brdges s based on he acquson of real lve load daa for heavy vehcles on hghways. Brdge wegh-n-oon B syses exhb advanages over radonal paveen wegh-n-oon syses n acqurng acual lve load daa owng o her porably and cos-effecveness. The B syse we presened heren aes he nfluence lne as a reference o calculae axle weghs. of he brdge s one of he os crucal paraeers n he applcaon of B syse as hey descrbe brdge behavor under he ovng load. For he praccal and coercal B syse oses algorh s wdely used and needs calbraon vehcles of nown wegh and axle spacng o calculae acual coordnaes based on easured brdge response. Therefore n order o prove he accuracy of axle wegh calculaon he frs poran ssue s o prove he algorh of calculaon based on he acqured brdge response easureen so as o ae he calculaed represen he acual brdge behavor. Zag 5 develops coercal B syse based on oses heory oses 979. The heorecal of he syse s adjused and revsed o acheve beer confory wh he acual suaon o acqure beer resuls of axle weghs and gross vehcle wegh GV hrough he response o a calbraon ruc of nown wegh passng he brdge Žndarč e al.. culy & Bren descrbe a pon-by-pon graphcal ehod of experenally dervng he fro he brdge response o a calbraon ruc. Bren e al. 6 propose a aheacal ehod o derve he fro drec easureens of he load effec n response o a vehcle of nown wegh and axle spacng. 57

2 Based on he feld es of a concree slab-grder brdge on hghway -78 n Alabaa n he U.S. he research heren proposes a ehod o calculae based on he easured brdge response whch s acqured fro he daa acquson syse wh he coercal B syse as a hgh rae of saplng 5 saplng per second. The algorh of calculaon s based on leas square ehods wh nzaon he dfferences beween easured and odeled response srans a d span when pre-weghed calbraon vehcles pass he brdge. Afer he acual s obaned he nex crcal ssue s o prove algorh o oban beer accuracy of calculaon for axle weghs. any researchers deonsrae ha he axle wegh calculaon based on oses algorh needs o solve a se of ll-condoned equaons owley e al. 8 González e al. 8 Bren e al. 9. The ll-condoned naure of he proble aes dffcul o dsngush ndvdual axle loads whn closely spaced axle cobnaons such as andes se-ralers and ralers. They also nvesgae ha he regularzaon echnque sgnfcanly proves he accuracy by addng a regularzaon er on he orgnal proble and fndng an opu regularzaon paraeer. The research heren s no o nvesgae he effecveness of regularzaon echnque bu raher o sudy he effecveness of he proposed odfed oses algorh based on he calculaed. The proposed algorh s applcable for he ypcal slab-grder brdge n he U.S. n he denfcaon of axle weghs and GV wh he coparson of sac weghs of ovng heavy vehcles. The aheacal equaons o calculae s and axle weghs are derved and he proposed algorh s pleened by copuer progra wren by he auhor n ATAB. The proposed algorh of hs research wll consder wo dfferen condons. For he frs condon he whole brdge s consdered as a sngle bea and each grder s assued o have he sae odulus secon Z and odulus of elascy E so ha he whole brdge jus has one ; for he second one dfferen grders are consdered o have dfferen properes E and Z. The proposed algorh for he frs condon s presened n hs paper ar and ha for he second one s presened n he followng paper naed as Algorh o denfy Axle eghs for an nnovave B syse- ar. SYSTE AD STAAT F SESS. syse The concep of B syse was developed by oses and hs ea n 979 oses 979 oses & Vera 987. Ths ehod uses nsruened brdge as a large sensor and he ransducers are ouned on he soff of each grder along a lne parallel o he longudnal drecon of he brdge o oban axle wegh and GV of heavy rucs passng he brdge oses 979 os 999. n recen years advanced B syses have shown rearable poenal n deecng overszed and overwegh coercal rucs n Europe Zag 5. n deecng vehcles os of he curren convenonal B syses requre wo axle or vehcle deecors nsalled on he paveen of each lane of neres o provde vehcle slhouee and velocy. For eporary nsallaons pneuac ubes or ape swches are wdely used bu he durably s poor and s no safe for personnel worng near raffc. ezoceracs sensors are uch ore durable bu are ore expensve and he nsallaon requres lane closures. owadays nnovave B syse replaces radonal ones wh axle deecor echnology naed le nohng on he road or free of axle deecor FAD Zag 5. Ths echnology requres addonal ransducers ouned underneah he brdge slab o nduce sgnals of he passng vehcles so as o deec he. For hs ype of B syse he advanage s ha oally elnaes all acons on he paveen and consequenly reduces coss of nsallaon and nconvenences o road users whou nerferng wh he raffc flow. n addon as all he equpen s hdden under he brdge all he deecon acon s oally nvsble o rucers and s parcularly effecve n ers of anenance especally n harsh claes. os poran of all he whole syse s porable and can be reused for any brdges so ha he whole cos of he easurng syse wll be sgnfcanly reduced n coparson wh paveen syse Zag 5. The B syse descrbed heren s a FAD syse. The an par of he B syse ncludes: sensors o acqure he sgnals ncludng weghng sensors and FAD sensors. The forer s ouned on he soff of each grder along a lne noral o he drecon of he brdge o wegh axle loads and GV he laer s nsalled rgh under he slab o deec he vehcle axles o oban nforaon of axle space speed and ec.; cabne o eep he processor of he syse elecroncs n he casng and cablng copuer and sofware; anenna personal dgal asssan DA and wreless fdely -F syse o represen he core of he B syse o councae wh each oher hrough he ranssson conrol proocol/nerne proocol T/; 4 caera syse o recognze and capure pcures of vehcles; and 5 solar panels o provde power supply. The coponens of he B syse we used heren are llusraed n Fgure. 58

3 FAD sensors; Spder; eghng sensors; 4 abne & panel; 5 Baeres housng; 6 Solar panels; 7 Solar panel nsallaon; 8 Anenna; 9 aera; DA Fgure. oponens of he B syse. Sensor nsallaon The brdge seleced for he B nsallaon s locaed on he hghway -78 Eas n Graysvlle Alabaa hree les wes of hghway -. The nuber of he brdge s B 76. The brdge s sooh on he jon and he approach o he brdge s even. The brdge s a hree span sple suppored T-bea brdge wh span 4 f.8 6 f8.4 wh wo lanes n each drecon. Fgure shows he overvew of he nsruened brdge wh B syse. Fgure llusraes he sensor poson of he brdge. Fgure. vervew of brdge on hghway -78 Tes span Elevaon BrnghaA 4'-7'' 8' 8' 4'-7'' 8' 8' 8' 8' 4'-7'' 4'-7'' 4' A 4' B Tes span 4' 6' 4' 4' ane ane 4' lan 4' 4' 4' B B B B4 78 EAST 78 EST Fgure. Sensor posons of brdge on hghway -78 A Tes span 4 FAD sensors 4 eghng sensors oe: 44 '' _ 8 8'.5'' 8 6'4'' 6' ross secon of Eas half 6'' '5'' 6'' '9'' ef lane ane gh lane ane he lne he lne 8.5''.5'' B B B B4. " " ---- oson of sensors.. " " ---- oson of sensors weghng sensors FAD sensors. ' B 6 6'' 4' 4' _ 45 '' B B4 6.75'' 8.5'' ' 4 6'' 6' 6'5'' 6.75'' * f.48c nch.54c S B B For he nsruenaon of he B syse he end span o he cy of Brngha drecon was seleced as es span Fg.. Four weghng sensors were ouned longudnally on he soff of concree grders one sensor for each grder wh one foo off he cenre because of he daphrag. To deec he vehcles 59

4 and acqure he axle nuber of vehcle and axle spacng four FAD sensors were ouned longudnally underneah he concree slab fee apar for each separae lane. TA ABAT F THE B SYSTE The nal calbraon es for he B syse was conduced on ov 8 8. The nal calbraon es was calbraed under he es condon - accordng o he European specfcaons for os 999. As was observed ha he represenave vehcle of hghway -78 was se-raler he nal calbraon was conduced wh wo seralers loaded o a capacy of 8 lbs 687g fro Alabaa Deparen of Transporaon ADT as pre-weghed rucs. The followng able provdes deals of he calbraon vehcles. Table. The nal calbraon vehcle nforaon of he brdge on hghway -78 Vehcle Axle wegh lb Axle dsance nch o. GV s axle nd axle rd axle 4h axle 5h axle A-A A-A A-A4 A4-A * lb.454 g nch.54 c Durng he nal calbraon es wo pre-weghed rucs were runnng wh dfferen speeds a dfferen lanes. The oal runs were 4 runs each lane wh runs. Durng he whole nal calbraon we ssed run n each lane and we had ulple presences for one e. Hence we have runs for each lane. Fgure 4 shows he pcures of he calbraon vehcles. Sac phoos hoos fro B syse ef: o. rgh: o. ef: lane gh: lane Fgure 4. Vehcles for he nal calbraon of brdge on hghway AGTH F AUAT AD FED TEST VEFAT 4. Algorh of calculaon For a sac vehcle a a ceran locaon on a grder brdge he oal longudnal gross bendng oen a a specfc brdge secon can be expressed as a funcon of e and can be defned by sung all he ndvdual grder oens. For each grder a e sep he bendng oen of grder equals: EZ where he bendng oen of grder ; E and Z he secon odulus and he odulus of elascy of he h grder respecvely; and he predced heorecal sran a e sep a he soff of he h grder. Each grder s assued o have he sae E and Z say E Z EZ. For hs brdge we assue ha all he grders has he sae properes as exeror grder. Then he oal bendng oen across he brdge secon a e sep s gven by equaon g EZ EZ where he gross bendng oens a d span a e sep ; and he su of he predced heorecal srans a all grders a e sep. hen a calbraon ruc wh nown axle weghs... passes he brdge a each e sep he correspondng heorecal load effec bendng oen caused by he calbraon ruc s gven by 5

5 The correspondng heorecal brdge response heorecal sran caused by he calbraon ruc a e sep s gven by EZ 4 5 EZ D f 6 v where he ordnae of he h axle a e sep ; f he scannng frequency of a hgh rae of daa acquson saplng syse; v he vehcle velocy; D he dsance beween axle and he frs axle; and he nuber of scans correspondng o D. The deals are llusraed wh a hree-axle vehcle and shown as Fgure D - D D f / v D f / v D f / v Fgure 5. ordnaes of calbraon vehcle a e sep Durng he whole calbraon we assue ha vehcle velocy s consan. Vehcle speed can be deerned by he wo FAD sensors of each lane ouned under he slab of he brdge a /4 and /4 respecvely. Fro e sep o say fro he oen he frs axle reach he poson pror o he brdge he sarng-pon for he recorded as a scan o he oen he las axle leave he poson poseror o he brdge recorded as b scan we wll have scans of he sran daa where a eans he nsan he frs axle reaches a specfed pon pror o he brdge and b eans he nsan he las axle leaves a specfed pon poseror o he brdge. There s no need o now he exac poson a whch he appled load causes he brdge o sar bendng. Therefore he uncerany surroundng he real boundary condons and he sall srans generally nduced near he suppors are avoded González & Bren. Based on he leas square ehod an error funcon beween he easured brdge response su of sran and he heorecal brdge response wll be defned as E 7 where s he su of easured srans a all grders a e sep. e use dfferenal calculus o dfferenae E wh respec o he se of nfluence ordnaes and se he expresson equal o zero. For splfcaon we use hree-axle calbraon ruc as an exaple Fg 5. o derve ordnaes. n hs case he heorecal brdge response sran under he calbraon ruc a e sep s [ ] 8 EZ Fro scans of daa acquson o he correspondng heorecal brdge response sran under dfferen scans s as: E 9 5

6 5 n he error funcon es relang o are and. Dfferenang E wh respec o se of nfluence ordnaes and nzng E he se of nfluence ordnaes wll ae he paral dervaves are zero. E A scan a he fron axle of he vehcle approaches he brdge; a scan a he las axle of he vehcle approaches he brdge; a scan b he frs axle of he vehcle leaves he brdge and a scan b he las axle of he vehcle leaves he brdge. hen b a < < s he general case when all axles are on he brdge srucure. Sung all he above equaons fro e sep he equaons are wren n a arx for as: {} {} ] [ where } { an ordnaes vecor; } { a vecor dependen on he axle weghs of he vehcle and he easured load response sran he eleen of he vecor a row s EZ ; and ] [ a sparse syerc arx dependen on he vehcle axle weghs lsed as followng. ] [ A A Fro arx [ ] we can fnd ha he an dagonal of he arx s he su of he squares of axle weghs. For a hree-axle calbraon vehcle he an dagonal s The upper rangle eleens are gven by ; ; ; 4 The oher nubers n hs arx are zeros. The correspondng lower rangular eleens are syerc. The ordnaes are calculaed hrough he calbraon vehcle passng he brdge. {} {} ] [ 5 The above equaons are specal for -axle vehcles. For vehcles wh dfferen nuber of axles slar equaons can be derved. f he calbraon vehcle has axles he arx equaon wll be: {} {} ] [ 6 {} {} ] [ 7

7 where { } n equaon 7 s slar o ha n equaon he eleen of he vecor a row s EZ. 4. Feld es verfcaon of calculaon The was calculaed based on he easured sran daa fro feld es on he brdge on hghway -78 n Alabaa. The calbraon vehcle was fve-axle se-raler able. n order o verfy he proposed algorh n calculaon runs on lane were calculaed. Vehcle o. s he calbraon vehcle whch s correspondng o run 4 and 5; vehcle o. s correspondng o run and. Fgure 6 llusraes he calculaed for run based on he above equaons; and Fgure 7 dsplays he coparson of easured srans and predced ones fro he calculaed. Fgure 7 shows an excellen ach beween easured srans and predced ones usng he calculaed whch llusraes he accuracy and effecveness of he proposed ehod o calculaed. n order o apply he calculaed s o represen he behavor of he acual condon usually we need o average he s of all runs or average soe seleced runs. Fgure 8 llusraes he calculaed s for all runs and Fgure 9 shows he resuls of average s consderng dfferen nuber of repeaed runs. nfluence lne nfluence lne alculaed fro brdge response Theorecal Theorecal alculaed fro brdge response Dsance Te Tes s Fgure 6. alculaed for run Fgure 7. easured and predced response of run Brdge Sran response easured brdge response redced heorecal brdge response nfluence lne coordnae Dsance Dsance run run run run 4 run 5 run 6 run 7 run 8 run 9 run Theorecal nfluence lne lne Dsance Dsance Theorecal Averaged of 9 runs whou run Averaged of 6 slar runs 5679 Theorecal Average of 6 slar runs 5679 Average of all runs whoud run Fgure 8. alculaed s of all runs Fgure 9. Average of s consderng dfferen runs Fro Fgure 8 we can see ha he obaned fro run s dfferen fro oher runs and we also denfy ha he easured srans appear slghly dfference fro he predced srans n coparson wh oher runs. Thus when we consder he calculaed as reference for axle wegh calculaon we should neglec run. Fro Fgure 9 we can see ha he averaged s of 9 runs s close o he averaged s of 6 seleced runs. Fro anoher pon of vew deonsraes he effecveness and sably of he proposed ehod o calculae. 5

8 5 AGTH F AUAT F AXE EGHTS AD FED TEST VEFAT 5. Algorh of axle wegh denfcaon hen a vehcle passes he brdge wh he sran of he sensors easured connuously gross bendng oen can be expressed as a funcon of e and forulaed by sung all he ndvdual grder oens. onsderng all he grders are dencal a e sep he easured gross bendng oens a d span equals o he suaon of he bendng oen of all he grders. g g EZ EZ where he easured gross bendng oens a d span; he easured bendng oen of he h ndvdual grder; g nuber of grders; he su of he easured srans a all grders a e sep ; and he easured sran a e sep a he soff of he h grder. Durng he passng of vehcles f he vehcle has he nuber of axles he heorecal nuber of unnowns for each vehcle wll be. Durng he ruc passage a dfferen e seps > a se of equaons wll be obaned for unnowns. Then he easured bendng oens are copared o he odeled bendng oens. Fgure gves as an exaple of he bendng oen equaon on a sply suppored brdge a e sep when he frs axle s x fro he suppor. h he axle spacng D D D and he bendng oen wh he predced heorecal bendng oen can be expressed as: g EZ EZ D - D - D D D f / v D f / v... D f / v Fgure. Bendng oens a e sep Then he predced heorecal sran s: EZ where he predced bendng oen a he sensor locaon; he ordnaes of he oal bendng oen for he h axle a a parcular pon a e sep ; and predced heorecal sran su of sran of he h grder g a e sep. oses algorh on B concep s based on he coparson of easured and odeled brdge response a d span and he defnes an error funcon beween easured gross bendng oens and predced bendng oens based on a heorecal oses 979. However he heorecal can no suffcenly represen he acual brdge behavor. The obaned fro easured sran daa wll be closer o he acual condon. Accordng o he afore-enoned algorh we can oban he correspondng based on calbraon rucs passng he brdge. Fro equaon for e seps we can ge nubers of predced sran: 54

9 EZ where s he nuber of scans of sran readngs and n a sple for we have { } [ ] { } where { } he vecor of heorecal sac sran; [ ] he arx of nfluence ordnaes; and { } he vecor of axle weghs o be deerned. Assung an error funcon E whch s he squares of he dfference beween he heorecal and easured srans; hus he proble can be solved by nzng he error funcon. E n arx for he error funcon can be wren as: T { } { } { } { } T T T T T T { } { } { } [ ]{ } { } [ ] { } { } [ ] [ ]{ } E 4 E 5 nzng he error funcon wh respec o he vecor of axle weghs resuls n: E T T T [ ] { } [ ] { } [ ] [ ]{ } 6 { } T { } [ ] [ ] T [ ] [ ] { } 7 Fro hs equaon he axle loads can be obaned and he GV can be obaned by sung axle weghs as GV 8 5. Feld es verfcaon of axle wegh calculaon Based on he calculaed s of he runs on lane we eploy he calculaed s o calculae he correspondng axle wegh he averaged s of 9 runs lsed n Fgure 9. Zhao deonsrae ha he scan nubers of easured sran daa should cover he whole process of vehcle passng he nsruened brdge n order o prove he accuracy of axle wegh calculaon. Heren we choose he case ha addng saplng abou / 5.s before he vehcle approaches he brdge and afer he vehcle leave he brdge o cover he process of he abrup change of he vehcle approachng or leavng he brdge. Table suarzes he calculaed resuls of all he en runs. Forunaely an exsng B syse operaed by ADT s 4 les wes of he brdge whch s one of ADT s paveen ses. For each run of he rucs weghed durng he research he resuls calculaed by he proposed algorh for B syse can be copared o he B syse wegh easureens. Ths allows researchers o deonsrae he relave accuracy of B syse and B syse. The es resuls of B syse s also lsed n able. For splcy we jus llusrae he GV resuls for B syse. n able A-A5 eans he axle nuber of calbraon vehcle fro he fron o he rear; GV eans he gross vehcle wegh; SA eans he sngle axle; 4 GA eans he group of axles; 5 For he ean and sandard devaon s. dev. of A A A A4 A5 SA and GV he nuber s whle ha for GA s. Table shows ha he accuracy of he proposed algorh n axle wegh denfcaon s effecve and accurae. The percenage error of each sngle axle wegh s less han % ha for GA s less han 6% and ha for GV less han 7%. The resuls n able also deonsrae ha he accuracy for GV s accepable for enforceen screenng based on he proposed algorh n calculaon and axle wegh denfcaon. oparsons wh sac weghs on a one-o-one bass for boh B predcons and B easureens have generally fallen below a % error for GV. B resuls deonsrae consderable repeaably of he predcons wh sandard errors under 5%. Fro able we can fnd ha B syse can provde beer predcon of GV han B syse. B syse has a sgnfcan poenal n axle wegh 55

10 denfcaon of ovng heavy vehcles. B syse llusraes sgnfcan advanage over B syse owng o s accuracy porably and cos-effecveness. Table Axle wegh coparson wh sac resuls of dfferen runs % e roposed algorh for B syse B A A A A4 A5 SA GA GV GV un % % % % % A AA A4A5 % % ean S. dev USS Based on he coparson of easured brdge response and predced heorecal ones fro he calculaed he proposed algorh n calculaon s effecve and accurae. The calculaed s closer o he acual of he brdge whch represens acual srucural behavor and provdes daa base for he healh onorng of he exsng brdges. For he ypcal brdge ype sple suppored concree slab-grder brdge n Alabaa and oher saes n he U.S. as well he proposed algorh n axle wegh denfcaon s repeaable effecve and accurae. By he proposed algorh n axle wegh denfcaon he percenage error of each sngle axle wegh s less han % ha for GA and GV less han 6% and 7% respecvely. 4 Feld esng of brdge on hghway -78 n Alabaa deonsraes ha B syse can provde beer predcon of GV han B syse by he proposed algorh based on coparsons wh sac weghs on a one-o-one bass for boh B and B syses. 5 B syse has a sgnfcan poenal n he applcaon for enforceen screenng and llusraes advanage over B syse owng o s accuracy porably and cos-effecveness. EFEEES ST European Specfcaon on egh-n-oon of oad Vehcles Fnal epor Appendx Ver.. EU- ST//8/99 ars Augus. U: hp://w.zag.s/repors/specfcaons/_specs.pdf González A. & Bren E.J.. nfluence of dynacs on accuracy of a brdge wegh-n-oon syse. roceedngs of rd nernaonal onference on egh-n-oon rlando Edors Jacob B. call B. & Bren E.J.:89-98 González A. owley. & Bren E.J. 8. A general soluon o he denfcaon of ovng vehcle forces on a brdge. nernaonal Journal for uercal ehods n Engneerng publshed onlne n ley nerscence U: culy. & Bren E.J.. Tesng of brdge wegh-n-oon syse n a sub-arcc clae. Journal of Tesng and Evaluaon 6: oses F egh-n-oon syse usng nsruened brdges. Transporaon Engneerng Journal ASE 5: 49 oses F. & Vera D oad apacy Evaluaon of Exsng Brdges aonal ooperave Hghway esearch rogra H epor ashngon D.. Bren E.J. Qullgan.J. & arou. 6. alculang an for drec easureens. roceedngs of he nsuon of vl engneers Brdge engneerng 59:-4 Bren E.J. owley.. González A. & Green.F. 9. A regularzed soluon o he brdge wegh-n-oon equaons. nernaonal journal Heavy Vehcle Syses6:-7 owley.. González A. Bren E.J. & Žndarč A. 8. oparson of onvenonal and egularzed Brdge egh-n- oon Algorhs. 5h nernaonal onference on egh-n-oon 5 Edors Jacob B. Bren E.J. onnor and Boueldja. ublcaons ars ZAG esel. 5. S Brdge egh-n-oon anual rd Edon ay Slovena Zhao H.. Brdge wegh-n-oon for brdge safey and anenance. h.d. Dsseraon Deparen of vl onsrucon and Envronenal Engneerng Unversy of Alabaa a Brngha Alabaa USA Žndarč A. avrč. & aln J.. The nex Generaon of Brdge egh-n-oon Syses. roceedngs of rd nernaonal onference on egh-n-oon Edors Jacob B. & Bren E.J. rlando USA 56