Tri-level Study of the Causes of Traffic Accidents. Volume 1, Causal Factor Tabulations and Assessments

NHTSA - Behavioral Safety Researchhttps://doi.org/10.21949/15250221977PDFResearch PaperTreat, John R.Tumbas, Nicholas S.McDonald S. T.Shinar, DavidHume, Rex D.Mayer, R. E.Stansifer, Rickey L.Castellan, N. J.Indiana University, Bloomington. Institute for Research in Public SafetyUnited States. National Highway Traffic Safety AdministrationUnited States. National Highway Traffic Safety AdministrationUnited StatesIndianaDriversTraffic accidentsData collectionAccident causesDOT-HS-805-085DOT-HS-034-3-535-77-TAC(1)NTIS-PB80121056DOT-HS-034-3-535Final reportThis is the Final Report of the "Tri-Level Study of the Causes of Traffic Accidents," performed by the Indiana University Institute for Research in Public Safety (IRPS), under contract to the National Highway Traffic Safety Administration (Contract No. DOT-HS-034-3-535). Several Interim and special investigation reports have been released previously. Volume I provides causal result tabulations from Phases II through V, and related analyses. Volume II presents several special analysis reports dealing with driver vision, knowledge, psychological make-up, etc. Phase I data differed in format, and were presented in a previous report. Data were collected on three levels of detail. Police reports and other baseline data on the Monroe County, Indiana study area were collected on Level A. On Level B, teams of technicians responded to accidents at the time of their occurrence to conduct on-scene investigations; a total of 2,258 investigations were conducted during Phases II through V. Concurrently, 420 of these accidents were independently examined by a multidisciplinary team on Level C. Other special surveys were also conducted. One or more human factors was cited by the in-depth team as a probable cause in 92.6% of accidents investigated in Phases II through V. Environmental factors were cited as probable causes in 33.8% of these accidents, while vehicular factors were identified as probable causes in 12.6%. The major human direct causes were improper lookout, excessive speed, inattention, improper evasive action, and internal distraction. Leading environmental accident causes were view obstructions and slick roads. The major vehicular causes of accidents were brake failure, inadequate tread depth, side-to-side brake imbalance, under-inflation, and vehicle related vision obstructions. Vision (especially poor dynamic visual acuity) and personality (especially poor personal and social adjustment) were found related to accident-involvement. However, as measured in this study, knowledge of the driving task was not shown to be related. /Abstract from report summary page/129