The 55 mph speed limit on US roads: issues involved

Abstract

State and federal experience with the national 55 mph (88 km/h) speed limit in the United States has shown it to be a major life‐saving policy. Even though the effectiveness of this policy has diminished in recent years as highway speeds have increased and other safety policies have made driving safer, 2000–4000 lives are saved each year due to slower and more uniform highway speeds. The effectiveness of this policy has been most criticized on rural interstate routes; these are designed for the highest speed driving and are generally the safest highways in the USA. The extra time spent driving on these highways because of the 55 mph speed limit is larger and the safety risks smaller than on other roads posted at 55 mph. Even so, the cost of lifting the 55 mph speed limit on these highways is substantial: roughly 500 additional deaths would occur on rural interstates each year. The current process by which the federal government measures state compliance with the 55 mph speed limit does not closely reflect different safety priorities, nor does it realistically reflect enforcement and judicial priorities. It could be improved by measuring compliance in a fashion that corresponds more closely with the implicit safety risks.