Safety and speed management: Speeding into a crash?

By Saumya Jain

According to a recent study conducted by the Insurance Institute for Highway Safety (IIHS), in the past 25 years 37,000 additional people have died due to increased speed limits in the United States. However, Canada is taking a very different approach to speed, as detailed in the April issue of ITE Journal, which is dedicated to safety through speed management.

This month’s ITE journal is focused on Vision Zero and speed management and describes Canada’s Safe System’s Approach to Road Safety, which has been very successful in deterring crash rates across the country. The approach involves implementing evidence-based measures on four different levels:  drivers, safe speeds, safe roads, and safe vehicles, with safe speeds being the most critical player. It is an important issue, especially when a number of states in the U.S. are considering increasing speed limits to match the 85th percentile.

In 2014, British Columbia increased speeds on more than 800 miles of rural road, some up to 75 mph. A review of the post-implementation performance of these highways using speed and safety data showed serious-injury crashes increased by 11 percent . The review led to reversing more than half of those speed limit increases and the implementation of a variety of safety improvements.

Source: Photograph by Johannes Rapprich

Meanwhile, in the U.S. IIHS looked at how increasing speeds have led to increased fatalities. Based on past crash data, IIHS has established that an increase of 5 mph can increase highway and freeway fatalities by almost eight percent and can increase fatality on other roads by three percent. An increase in crash impact speed from 20 mph to 30 mph puts a pedestrian at a five to eight times increased fatality risk. With such a sensitive relationship between speed and crash fatality risk—especially at the slower speeds normally found on local streets—speed management and safety decisions need to be made very carefully.

The relationship between high speeds and serious injury or fatal crashes has been established repeatedly in the past years, but the U.S. and Canada are taking different approaches to speed-related safety. As the author of the ITE article on the Canadian approach writes, “It has been noted with the 85th percentile, drivers should not set speed limits, but speed limits should be set based on the biomechanical tolerance of blunt-force trauma.”

Saumya Jain is a Senior Associate at SSTI.