Saturday, April 25, 2015

Roundabouts in the US

I first became intrigued by roundabouts based upon the Colorado experience.  As a traffic engineer living in Denver, I was keenly watching as the Town of Avon decided to place five roundabouts in their community to relieve traffic congestion.  This was a risky move.  The interchange of Avon and Interstate 70 was horrible.  During the peak hours, traffic would back up onto the interstate - af very dangerous situation.

But the roundabouts were going to change all this - at least the traffic engineers hoped so.

The local newspaper was not convinced.  They ran editorial after editorial denouncing the proposed solution and claimed that any lives lost would be the fault of these roundabouts.  I was impressed by the fortitude of the engineers!

When the day came to open the roundabouts, everyone was waiting to see what would happen.  And guess what did happen?

 Nothing!  That's right.  For years, this interchange would frequently back up but for the first time that anyone could remember the traffic flowed smoothly.  It was an engineering success story.

After that, roundabouts were proposed at many locations in Colorado.  The City of Colorado Springs placed several roundabouts along Lake Avenue.  These were highly successful, but there was concern over the potential traffic accidents.

In 1998, I was the conference chairman for the Colorado chapter of the Institute of Traffic Engineers.  One of the issues that plagued the traffic community was what standards should be used to design and analyze these roundabouts.  We decided to bring in experts from around the world.  We invited experts from England to Australia come to Loveland, Colorado and share their experience.  It was probably the most exciting seminar I have ever been involved with.  Particularly when the two experts almost came to blows about which method to analyze the roundabouts was greater.

The Transportation Research Board also recognized the deficiency and began to fund research into all aspects of roundabout operation.  These findings have been implemented into the 2010 Highway Capacity Manual.