Incidence of Speed on Risk of Severe Injuries or Fatalities During Collisions on Urban Roads

All stakeholders seem to agree that speed is one of the main causes of road collisions. Thus road safety experts determine speed limits based on road environment. The present study aims at validating the 50 kph legal speed limit in urban environment in the province of Quebec, Canada, and to quantify the risk to be involved in a collision with fatal or serious injuries when this limit is exceeded. In this study, reconstruction of collisions with fatal or serious injuries on urban roads of the city of Montreal was carried out. The study encompassed 39 collisions which occurred on roads with posted speed limit of 50 kph during the years 2001 and 2002. The selected collisions had to satisfy a number of criterion allowing to eliminate masking effect such as alcohol and illegal maneuver. The majority of cases were fatal collisions while the remaining cases involved life threatening injuries. In order to evaluate the relative risk of being involved in a collision with fatal or serious injuries, the traveling speed of 4 control vehicles was recorded. These vehicles were then traveling at free speed on the same road, under similar weather conditions, and at same time of day as the vehicle case. Fifty kph speed reduction scenarios were applied to the collisions for which the case vehicle speed exceeded the legal limit. This made possible the determination of the effect of excessive speed on collisions with fatal or serious injuries. Results of the study show that if the drivers had followed the 50 kph limit, there would have been a reduction of 44 % in the total number of collisions with a reduction of 83 % of frontal collisions, 33 % of side collisions and 23 % of collisions with pedestrians. The results also show that the relative risk of being involved in a collision with fatal or severe injuries is greatly increased at speeds exceeding the legal limit, with a multiplicative factor of 81 at travelling speeds above 80 km/h. Global data shows quite clearly that the legal speed limitation of 50 kph in an urban environment constitutes a valid reference in terms of collision injury reduction and overall road safety.


  • English

Media Info

  • Media Type: CD-ROM
  • Features: Figures; References; Tables;
  • Pagination: 13p
  • Monograph Title: TRB 86th Annual Meeting Compendium of Papers CD-ROM

Subject/Index Terms

Filing Info

  • Accession Number: 01044937
  • Record Type: Publication
  • Report/Paper Numbers: 07-3217
  • Files: BTRIS, TRIS, TRB
  • Created Date: Feb 8 2007 7:55PM