Should U.S. Interstate Highways Have Higher Speed Limits?

The debate over the appropriate speed limits on U.S. Interstate highways is a contentious issue, especially in remote areas like New Mexico, Arizona, Nevada, Utah, Wyoming, Montana, and Idaho. Advocates for higher speed limits argue that these regions are designed for much faster travel, while others are concerned about safety and the potential for increased accidents.

The Case for Higher Speed Limits

Engineering Methodology: The principle behind the argument for higher speed limits is rooted in an engineering concept that sets speed limits at the 85th percentile, meaning 85% of vehicles travel at that speed or slower. This threshold is believed to be the safest speed, as it minimizes crashes. However, the actual speed limit is rounded up to the next 5 MPH increment for practicality.

While this theory holds promise, the real-world application is often influenced by politics rather than engineering. Government officials tend to set speed limits lower than the recommended 85th percentile speed to seem more cautious and appear to prioritize safety. This approach can be viewed as a politically motivated compromise rather than a genuinely safety-oriented solution.

Modernizing Speed Limits

To address this issue, a more precise approach is necessary. With the modernization of roadways and vehicles, the current statistical crash incidence curve may have shifted to higher percentiles. The presence of safety devices like breakaway signage, rumble strips, reflective paints, modern lighting, and improved vehicle designs with crumple zones, collapsible steering columns, airbags, and disc brakes can play a crucial role in this shift.

It is time to revisit the speed limit decision-making process. Using modern engineering data and abandoning political influence could lead to a more rational and effective approach. The ultimate goal should be to ensure that the speed limits reflect the latest safety metrics and technological advancements.

A Modernized Approach to Speed Limits

Urban vs. Rural Areas: In dense urban areas, freeways should maintain a speed limit of 65 mph to account for the increased traffic and frequent merging. However, in suburban areas with fewer curves and fewer exits, a higher speed limit of 70 or 75 mph would be appropriate.

For rural areas with wide freeways and no curves, a different approach is recommended. Implementing separate lanes with a 80 mph speed limit for trucks and some cars, while allowing unlimited speed for others, could be considered. This system could be enforced through a solid white line with breaks near exits for controlling access to and from the unlimited speed lanes.

Germany's Autobahn

A frequent comparison is made to Germany's Autobahn, which does not have general speed limits, arguing that the U.S. Interstate System was designed to mirror this concept. This comparison highlights the potential for the U.S. to adopt a similar policy, especially for certain stretches of highway that align with this design philosophy.

Conclusion

The appropriate speed limits on U.S. Interstate highways should be a data-driven decision, reflecting the latest engineering standards and technological advancements. By modernizing the approach and removing the political influence, we can ensure that the roads are both efficient and safe.