Road safety activists and several states are working to overturn a decades-old practice that determines speed limits in the United States. The current system, which bases legal speed thresholds primarily on how fast drivers typically travel on a given road, is facing growing opposition.
The push represents a significant shift in traffic management philosophy. For years, traffic engineers have set speed limits using the “85th percentile rule” – a method that measures how fast most drivers go on a particular stretch of road and then sets the limit near that speed.
The Growing Movement for Change
The movement to change speed limit methodology comes amid concerns about rising traffic fatalities in recent years. Safety advocates argue that the current system creates a self-fulfilling cycle: faster driving leads to higher speed limits, which then encourages even faster driving.
Several states have begun exploring alternative approaches to setting speed limits that prioritize safety over driver behavior. These new methods often take into account factors such as:
- Presence of pedestrians and cyclists
- Road design and condition
- Crash history and severity
- Surrounding land use (residential, commercial, school zones)
The Case Against the 85th Percentile Rule
Critics of the traditional method point out that it essentially allows the fastest drivers on the road to determine what’s legal. They argue this approach ignores vulnerable road users and community safety concerns.
“Setting speed limits based on how fast people drive rather than what’s actually safe makes little sense,” said one safety advocate involved in the reform effort. “It’s like letting students set their own passing grades.”
Research has shown that even small increases in speed can dramatically increase crash severity. A pedestrian struck by a vehicle traveling at 30 mph has about a 40% chance of being killed, while that risk jumps to nearly 80% at 40 mph.
State-Level Changes Underway
Some states have already begun implementing new approaches. California passed legislation allowing cities to consider factors beyond driver behavior when setting speed limits. Minnesota, Washington, and Oregon have made similar moves toward context-sensitive speed limit setting.
Transportation officials in these states are developing frameworks that consider the safety of all road users, not just drivers. This includes analyzing how roads function within communities and their impact on residents.
The Federal Highway Administration has also shown openness to new approaches, updating guidance to allow for more flexibility in how local jurisdictions determine appropriate speeds.
Opposition to these changes comes primarily from some transportation engineers and driver advocacy groups who argue that artificially low speed limits may be widely ignored, potentially creating speed differentials among vehicles that could lead to accidents.
As this debate continues, communities across the country are watching closely to see how these policy shifts might reshape American roads and the safety of those who use them.
