The objective of this study was to identify those principal features of bridges which may be related to accident frequency and severity and to provide some further insights toward highway safety. Accident data from interstate and parkway (toll) routes and from primary and secondary systems were compiled and summarized. The major findings were:

  1. Bridge-related accidents, particularly involving severe accidents, were significant percentages of the total accident experience on interstates and parkways.
  2. There were fewer bridges per mile on the primary and secondary highway system and a lower percentage of bridge related accidents than on interstates and parkways.
  3. The severity of bridge-related accidents was higher than the severity of all accidents,
  4. The severity of bridge-related accidents on primary and secondary highways was almost identical to the bridge-related accidents on the interstate and parkway systems.
  5. Collisions with entrance posts resulted in more fatal accidents than other accidents involving bridge structures.
  6. The benefit of full-width shoulders was illustrated,
  7. Guardrail protection at bridge piers has proven less than totally effettive. A very limited number of accidents involved earth mounds. Further development of earth mounds may be warrented.
  8. Openings between parallel bridges on divided highways create a recognized hazard.
  9. The high percentage of nighttime accidents suggests a problem with visibility of the structure,
  10. An exceptionally high percentage of accidents occurred during snowy or icy conditions,
  11. On primary and secondary highways, several fatal accidents occurred at bridges with curved approaches,
  12. The bridge railing was inadequate on some of the bridges on primary and secondary highways.
  13. One-lane bridges on the secondary system constitute a hazard.

Report Date


Report Number

No. 427

Digital Object Identifier



The contents of this report reflect the views of the author who is responsible for the facts and accuracy of the data presented herein. The contents do not necessarily reflect the official views or policies of the Bureau of Highways. This report does not constitute a standard, specification, or regulation.