TechnicalSession F{o. 6 Srfety Developmentsof Goods Vechiclesand Buses L. Strandberg,Chairman, Sweden ImprovedCommercial Vehicle Conspicuity and SignallingSystems therefore,that countermeasuresaimed at RussellL. Smith' It would scem, a smallpcrcentage of vchiclescould leadto a signil'icant J. Burger, William redrrctionin a rclativelylarge percetrtage oi'i'atalities, Kenneth Ziedmnn.and Onc crbviouscountermeasure would be the improved Msrk Mulholland visibilityor conspicuityof largetrucks. 'l Vector Enterprises,Inc. his papersummetrizes a 3-[year project,fundcd by the U.S. f)epartmcntof Transportationand dcsigned to developand cverluateinrproved conspicuity systems for Abstract largctrucks. Vehicle-into-large-truckaccidents produce a dispro- Rationale portionatelylarge number of fatalitics.It ishypothesized a truck's visibility or conspicuitywill Imposing new Federal lighting and reflector system that increasing 'l reducethe numberof vehiclcscolliding with trucks. he requirementswould clearlyirnpact directly on thetrucking purposeof this projectwas to analyzethoroughly this industryand indirectlyon everycJriver. l'hus, prior to the specificaccident problem, estabtish inf ormation require- developmentand test of proposednew consptcuity ments of other drivers,revicw the stateof the art of systcms,every el'fort was made to provide a thorough conspicuitytechniques, dcsign and conducta seriesof statementof the Problettt. conspicuityexperirnents, design a newintegrated lighting The proicct was composedof the following tasksand system,dcsign an augmented,lou-ctlst suhtasks: and rrrarking 'l'ask retlectorizedsystem for retrolitting on largetrucks, and l. l: Define and analyzethe vehiclc-into- fielcl test the augmented system on lleets of trucks. truck collisionProblem. Approximately 2,000 trucks were fitted with the aug- r Iteview rclcvantliterature mented $ystetn,and accidentrates are curlcntly being . lnterviewtrucking comPanies monitored and compared with those of a matchcd . Analyzeaccident data controlgroup of 2,000tlucks. At thetime of thiswriting, r Developfunctional requirementsof drivers the 2-yearficld stutly is nearingcomplction. About 70 r Analyze retrorellectiveand fluorescent , percentofthe total accidentscxpected have been analyzed' materials and thc resultsthus far indicatethat the trr.rckstreated r Evaluatc current Federal Motor Vehicle with the reflectorizedsystems are being hit at a lower ratc Safcty Standards (retrofit) than arecontrol trucks. lncreasing conspicuity, therefore, 2. Task 2; Designand evaluateaugmented appearsto be an el'lectivemethod of reducingvehicle- and newintegrated lighting and rcflector systetns. into-truck accidents. r I)csign various conspicuitysystems and conduct laboratory,l'ield experiments t Designa specificlow-cost augrnented system Introduction for field tcstingon truck fleets I Preparea detailedplan for conductingthe ': fiehl test of thc augn'rentedsystcrn Purpose r Designa new,integratcd conspicuity systcm for original equipmentmanufacturc '[ask (.onduct Large trucks' equal to or in excess of 26.000 lb 3. 3: field test of the augmented constituteless than 2 pcrcentof the total populationof systcllton selectcdtrr.rck lleets. vehiclcsin the [Jnite<t States but arc nevertheless involved r Selectconspicuity materials in acci<lentsyiclding nearly 9 percent of all traffic Selecttruck fleets fatalities. The great majority of thcse fatalities are r Install conspicuitYmaterials occupantsof passengercars that collidc with suchtrucks. , . Collectand analyzeaccident data 841 Experimental Safety Vehicles The following sections emphasizemajor findings, Scenarioanalysis de monstrated that a truck conspicuity analyses,and considcrationswith respectto the above systerncommunic-atcd general rathcr than specif ic inlbr- three tasks.Vastly more detailcdaccounts can be found mation with respcctto its dynanrics.For cxample,the in (3) and (12),As of thiswriting, the projccr is not quite currentsystcm for indicatingchanges in velocityhas only complctcd,there being a few monthsremaining in Task 3 two lttates:the brake light is eitheron or off. Thc vehicle 'lask licld tcsting.The resultsreported I'or 3 reprcsent caneither be stopped, accelerating, maintainirrg a constant approximately 70 percent of the total accider-rtdata specd,or decelerating,and, with regardto accclcration expectedin the field test. anddeceleration, the rateol'change can valy substantially. Thus, the current systsmrelies on the drivcr to perceive Task l: Defineand Analyzethe Vehicle- cherngesin rateof closurc,an extremclydifficult pcrceptual task,particularly at nightwhere much of thevisual input Into-Truck CollisionProblem is sevcrely redrrced. The analysesof vehiclc-into-truckaccidents and associatedsccnarios clearly ind icated a needfor improved Analyze Accident Data truck conspicuitysystcms that would providedrivers with the following specificinlolrnation on the l.ruck's Reviewsof extensiveanalyses of a numbcr of accidcnt positionand dynamics: r data bases reveal that large trucks are struck about Prescnceof a vchicle equally often in thc rear and side, the latter including r lndicationol'a truck r both sideswipcsand perpcndicularimpacts. They are also f)istancc equallyolien struckat nightor in dimly lir cnvironmcnts ' Speed as during the day and are struckahout equally often on r Whctherit is maintaininga constantspeed t rural and urban roadsthat are both lcveland graded. , Whethcris it accclcrating r Rear impactstcnd to occurwhen thc truck is travcling Whether it is decelerating r straightahead and rnovingslowly or stoppingor stoppcd Whetherit is stopping r on the roadway.The followingr-lriver eithcr ( l) d ocsnot Whetherit i'r stopped r seethe truck at all, (2) seesthc truck but lnisjudgesits Whetherit is backingup r motion and/or distance,Qr (3) corrcctlyperceivcs the Whetherit is rnaintaininga constantdirection r truck's dynarnicsand distancebut not within sufficient Whcthcrit is turning time to avoida collision. A numhcr of techniqucsexist for satisfuingthe above Trucks are struck perpendicrrlarlyin the side most functional rcquirements,Unfortunately, most of thcm would bc too costly to be corrsidcredseriously at this oftcn when turning or beingirstride lanes, e.g.. backing. 'fhus, making U-turns, etc., but are ollen sideswipedwhen timc. lessthan optimal soh.rtionsrnust be sought travcling straightirhead. that are, r'rcvcrtheless,signilicant irnprovcrnentsovcr In view ol'thc foregoing,therefore. it would appcarthe current systems.Such solutionsmust derivefrom an conspicuityproblcm with largctrucks is not restrictedto undclstanding of how drivers detect and identify the nighttimeconditions or specil'iclighting and marking presenccof a truck and acquireknowledge of itsdynamics. It hasoften been said that mostaccidents are wholly or systerns.l rucksare apparerrtly inadequatcly conspicuous 'l duringthe day, and boththeir sidcs and rcar.cnds seem in principallycaused by inattentivcrbchavior. hus,cletcction needol' incrcasedconsnicr.ritv. perlormanLrcdepen<js, at leastpartially, on theability or conspicuityof a target (e.g.,trucks) to compensatcfor inattentionand penetratca driver'sfield ol'view. Develop Functional Requirements It is generallybclieved that luminancer;ontrast is thc major cue for detection(4).Ilowever, while lurninous Basedon the analysesof accidents,l9 scenarioswere contrast is ccrtainly necessarytbr detection,a stimulus establishedthat encompassednearly every situation in may not attrac:ta driver's attention in a cluttered whichtrucks are hit by cars.F,ach sccnario was analyzed environment.llurg and Ilulbert(2)and Burg and Becrs( l) at a level of detail necessaryto identil'ythe functional demonstratedthat the uniqucshape of a stimulusis of recluirementsof truck communicirtionsystcnrs, These considcrableimportance in attracting attention and scenaritr$included vehicle lorlations. directions of move- establishingrecognition. For examplc, reflector.scom- ment, and varying speeds.Stopping distanceswere pletely or.rtliningwhccls attract far more attentionthan computedthat indicatcdthe distances at whichthe driver do nondistinct ref'lcctorsarbitrarily locateclon bicyclcs ol'thc strikingvehicle would havcto applythe brakesto and motorcycles. stop ol slow sufficientlyto avoid a collision.Dyrramics of Drivers employ subjectivejudgments in determining both vehiclesand systemreirction times werc included in distances and dynamics of other vehicles.Carefully thc computirtions. controlled lahoratory experiments indicate that size 842 Section4. Techniaal^Sessloas changesof an object moving in depth constitute the to observationangles. At an observationangle of 1.0o, dominantcue in iudging motion in depth(9,10).Appar- relativeintensity rnay typically be only onc-tenththat of ently. thc largerthe objectappears to an observcr,the 0.l'. smallerthc changein sizcnccrssary to detectmotion( I I ), The retroreflectivcclevices relevant to trucks include The speed differencesin vehicle lollowing become materialscontaining ( I ) sphericalglass bead elements, or increasinglyimportant the closerthe followingvehicle (2) cubccorner or prismaticelerncnts. In eachcasc, it is approachesthe leading vehicle. lttleson ( 195l) notedthat theclements that rellectthc incidentlight.'l hc glass bead whilesizc changes in an objectprovide motion cues.thc materialsinclude thosr havingbeads paltially imbedded judgment of distanccol an objectdepends on a priori within a supportingsurlace such as paint and paftially 'l known characteristicsol the object. hus,