Who Determines Speed Limits?

Speed limits are set by state and local governments. Most states have a maximum allowable limit–70 MPH in PA–that determines the upper limit for speeds on highways and the like. From that point, officials examine where the limit needs to be set. There are specific regulations for certain areas, such as residential areas (25 MPH), business districts (30 MPH), and other roads (generally 55 MPH). These limits are referred to as “statutory limits” and are based on the safest maximum speed under which vehicles can operate under ideal conditions.

How are Speed Limits Determined?

If you ask a qualified professional how speed limits are set, such as a transportation safety engineer, you’ll likely hear the term “85th percentile.” This term comes from the determination method that takes how we drive into consideration. Though it may come as a surprise that our impulses as drivers are taken into account, they are a factor in setting limits. If speed limits are set too high, drivers might ignore them and drive slower; too low and drivers might disregard them and drive fast anyway.