Technical Tuesday: The need for speed...limits

Today's blog will answer a question we received via social media recently about speed limits.

 

To answer this question, it’s best to start by looking at what the actual speed limits in Kansas are.  Check out the map below.

All four-lane highways or dual-carriageways in Kansas are 70 mph and above.  Our interstate routes (shown in red on the map) are 75 mph and above.  These routes have no cross traffic, which is why they are at the higher speed.

The majority of the two-lane highways in the state have 65 mph speed limits (shown in dark blue on map).  As you can see, there are some highways that have speed limits of 60 mph or below.  The reason for these lower speed limits can be attributed to a number factor such as a heavy traffic, roadway geometrics or high crash rates.

This wasn’t always the case.  In 1973 Congress enacted the National Speed Limit in an effort to conserve gasoline and it was set at 55 mph. In the 1980s it was increased to 65 mph on some roads, then in 1995 the law was repealed and each state was then allowed to choose their own speed limit.

Until 2011, the speed limit on all major freeways was 70 mph in Kansas.  When the Kansas Legislature passed the new maximum speed limit of for separated, multi-lane highways, KDOT then made the choice of which highways would be increased to 75 mph. All of the routes that were chosen for the increased speed limits are freeways and have controlled access to and interchanges. Other factors that were considered for choosing those particular highways were whether the road was in a rural or urban area, the amount of traffic and the speed limit in the surrounding states. (Our neighbor to the west Colorado’s speed limit on I-70 is 75 mph, while our eastern neighbor Missouri is 70 mph.) Basically, at least in Kansas, the more populated the area, the lower the speed limit.

Below is map of the current maximum speed limit in each U.S. state.  As you can see a good portion of the country is at the same limit or higher than the United Kingdom, it just depends on where you are at while traveling in the U.S.

If you have any more questions about speed limits or another transportation-related issue, feel free to pose it in the comment box below or ask us on twitter @KDOTHQ.