New NHTSA Data – Speed Data Shows Lethal Legal Speed Limits Involved In Most Pedestrian And Bicyclist Deaths

This is part three in a series on new National Highway Traffic Safety Administration (NHTSA) data. Parts one and two looked at driver-related and vehicle-related data elements. In total, 17 data elements were added to the query fields available in the Fatality and Injury Reporting System Tool (FIRST). This post looks at two data elements that provide speed-related data on pedestrian and bicyclist deaths.

In the United States Department of Transportation (USDOT)’s National Roadway Safety Strategy, Safer Speeds is one of five objectives and a core concept of that objective is that the rate of survival in a crash decreases as the speed of the vehicle involved in the crash increases. According to USDOT, a person walking hit by a vehicle at 32 miles per hour (mph) has a 25% risk of death, and that increases to a 50% chance of death at 42 mph.

The data element “Striking Vehicle Driver Speed Limit” allows us to report on the speed limits for drivers when they struck and killed a person walking or biking.

• For pedestrians, 65% of deaths with reported speed limits were on roads where the legal speed was 40 mph or more, the most common speed limit for the striking driver in a crash that killed a person walking was 45 mph.
• For bicyclists, 62% of deaths with reported speed limits were on roads where the legal speed was 40 mph or more, the most common speed limit for the striking driver in a crash that killed a person biking was 45 mph.

This means that most pedestrian and bicyclist deaths occur on roads where the expected outcome of a crash is a more than 50% chance of death. As bicyclist and pedestrian deaths rose to 40-year-plus highs in recent years, the majority of the increase in deaths occurred on roads with speed limits of 40 mph or more.

The World Health Organization and the 140 countries, including the United States, who signed the Stockholm Declaration on Road Safety have committed to the idea that there should be a maximum road travel speed of 30 km/h (about 20 mph) in areas where vulnerable road users and vehicles mix in a frequent and planned manner, except where strong evidence exists that higher speeds are safe. 

For both bicyclists and pedestrians in the United States, few deaths occurred on 20 mph speed limit roads, averaging less than 20 people per year for both person types. The United States does not track miles of roadway by speed limit or the miles of roadway with 20 mph speed limits. 

Within the cycling community there is a recognition that vehicles overtaking cyclists are one of the most common sources of severe crashes, with the movement for safe passing laws motivated by this recognition. NHTSA data that incorporates speed limits backs this recognition up, and adds important context by showing that roads with 55 mph speed limits are the most common roads where an overtaking driver hits and kills a person bicycling. At lower speed limits, intersection-related crash types appear more common.

For people walking, crossing the road and while a driver proceeds straight is the most common crash type for roads with speed limits of 55 mph or lower. At 55 mph, walking along the road briefly becomes the most common crash type before being surpassed by “unusual circumstances” and “crossing expressway.” The crash group “unusual circumstances” appears to mostly be people whose vehicles became disabled, but also contains many people who are killed as part of a secondary crash after a vehicle collides with another vehicle or object.

Deadly high-speed roads where a crash is more likely than not to kill a person walking exist in many urban and rural areas. The most common speed limit for a driver who strikes and kills a person biking or walking is 45 mph in an urban area and 55 mph in a rural area. In rural areas, 55 mph is the most common speed limit where a person biking or walking is killed for all roadway types except interstates.

The data available from NHTSA shows that for most people killed while biking and walking the speed limit itself is lethal, and speeding is not required to create a deadly situation. For what it is worth, speeding is much less likely to be indicated in a crash that kills a person biking or walking. Speeding is involved in about 30% of all traffic deaths, but only about 9% of bicyclist deaths and 8% of pedestrian deaths. It is unclear how people were reported to be speeding on roads with unknown speed limits.

The other new data element related to speed is “Striking Driver Travel Speed.” This data element appears to be less useful than “Striking Driver Speed Limit” for at least two reasons:

1. Most pedestrian and bicyclist deaths do not involve speeding according to NHTSA data. The rate for both person types is less than 10%, while for all traffic deaths about 30% involve speeding.
2. The data is not reported for 56% of fatal crashes and the reporting has not improved over time.