This Penske Social Blog post aims to answer some common questions about speed limits and clear up common misconceptions that people have about speed limits and their effect on safety.
Q. How are speed limits be set?
A. Traffic engineers maintain that speed limits should be established according to the 85th percentile of free flowing traffic. This means the limit should be set at a level at or under which 85 percent of people are driving. Numerous studies have shown that the 85th percentile is the safest possible level at which to set a speed limit.
Q. Isn’t slower always safer?
A. No, federal and state studies have consistently shown that the drivers most likely to get into accidents in traffic are those traveling significantly below the average speed. While we at Penske always encourage you to be safe, research has shown that those driving 10 mph slower than the prevailing speed are more likely to be involved in an accident. Therefore it is encourage to stay with the pack.
Q. Wouldn’t everyone drive faster if the speed limit was raised?
A. No, the majority of drivers will not go faster than what they feel is comfortable and safe regardless of the speed limit. For example, an 18-month study following an increase in the speed limit along the New York Thruway from 55 to 65 mph, determined that the average speed of traffic, 68 mph, remained the same.
Q. Do higher speed limits lead to more accidents/ traffic fatalities?
A. No, if a speed limit is raised to actually reflect real travel speeds, the new higher limit will make the roads safer. When the majority of traffic is traveling at the same speed, traffic flow improves, and there are fewer accidents. Speed alone is rarely the cause of accidents. National Highway Traffic Safety Administration (NHTSA) claims that 30 percent of all fatal accidents are speed related. It is believed that differences in speed are the main problem. Reasonable speed limits help traffic to flow at a safer, more uniform pace.
Q. Are US roads more dangerous than ever before?
A. No, our nation’s fatality rate (deaths per 100 million vehicle miles traveled) is the lowest it has ever been. The total number of fatalities has also stayed relatively stable for several years. They do occasionally increase, but given that our population and the distance the average person drives are also increasing, this is not surprising, nor is it cause for alarm.
Q. Don’t lower speed limits save gas?
A. No, research has shown that the 55-mph National Maximum Speed Limit, which was enacted specifically to save gas, had practically no impact on fuel consumption. This is partly because people do not obey artificially lower speed limits. It is also because the differences in travel speeds that result from unreasonable limits waste gas. Most fuel is used to accelerate to a given speed. Speed limits based on actual travel speeds promote better traffic flow, which reduces the amount of braking and accelerating on our roads. This has a positive effect on fuel consumption.