WKYT Investigates | 10 years later, how is Lexington’s double crossover diamond doing?

A novel solution has now become normal. And it’s made the corridor safer.
WKYT Investigates | 10 years later, how is Lexington’s double crossover diamond doing?
Published: Sep. 2, 2021 at 3:43 PM EDT
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LEXINGTON, Ky. (WKYT) - Turns out, driving on the left side of the road may have its advantages.

In the decade it has been open, Lexington’s double crossover diamond interchange has reduced crashes in a high-traffic area, collision data shows.

“It’s helped out a lot, at least with the consistency,” Jeff Neal, director of Lexington Traffic Engineering, told WKYT’s Garrett Wymer. “It’s fairly predictable, moreso than it was before. You just didn’t know if you were going to get through or not in a reasonable time.”

More than 33,000 vehicles travel daily on a section of Harrodsburg Road near New Circle Road, according to transportation cabinet traffic counts.

State reports show that, before the diamond, Harrodsburg Road at that location had the highest crash rate of any major artery in the region. A total of 484 crashes were reported on the half-mile stretch between Beaumont Centre Parkway/Corporate Drive and Alexandria Drive/Pasadena Drive from Jan. 1, 2008 to Dec. 31, 2010 - the last two full years the previous intersection was open.

(Current access to pre-2010 annual crash data is limited due to KyOPS archive storage constraints.)

For comparison, a WKYT Investigates analysis of Lexington Police Department crash data obtained through an open records request shows that crashes on that stretch of Harrodsburg Road the first two full years the diamond was open dropped 63 percent: only 180 crashes were reported there 2012-2013. No two-year span since has had even half the number of crashes as 2008-2010 (pre-diamond).

“We take statistics all of the time, compile data and that is what we have found: that it has been a successful project with eliminating crashes, eliminating left-turn movements and eliminating actually the conflict in the entire intersection area,” said Natasha Lacy, public information officer with the Kentucky Transportation Cabinet, District 7.

By design, the double crossover diamond (DCD) interchange gets rid of left turns across traffic. Instead, drivers cross over to the opposite side of the road, allowing them to get on New Circle unimpeded. Engineers praised the design as a way to help with traffic flow and cut down on collisions.

Looking at a seven-year period before and after the diamond (2004-2010 and 2012-2018, with 2011 omitted due to construction) state transportation statistics show:

  • overall crashes dropped 20 percent
  • minor injury crashes dropped 42 percent
  • property damage-only crashes dropped 15 percent
  • rear-end crashes dropped 68 percent
  • angle crashes dropped 39 percent
  • sideswipe crashes increased 35 percent

The innovative interchange on Harrodsburg Road at New Circle was the first of its kind in Kentucky and only the sixth in the U.S. at the time it was built. Now it is one of three currently open to traffic in Kentucky; two more are under construction and three - including another one in Lexington (Leestown Road at New Circle) - are under consideration. (See embedded map.)

One problem with the interchange on Harrodsburg Road, traffic engineers say, is that the traffic lights at the intersections on either side are too close to the traffic lights at the ramps, which limits capacity and boxes in the signal timing. (Engineers point out that the layout along Leestown Road right now is similar.)

City traffic engineers say the area is over-capacity, but planners are currently looking at some long-term ways to help with that, such as lengthening turn lanes or adding through lanes - part of a study under way to identify bottlenecks around Lexington.

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