September 2024

ROAD DESIGN 101

Construction season is very much in full swing, and multiple projects across Kentucky are nearing completion. Sometimes wrapping up a project means implementing a new traffic pattern that might be unfamiliar to drivers. In this issue, we’re going to look at some of the efficient road designs that have been introduced to the Commonwealth in recent years. For more details on any of these traffic patterns, or a wide range of others, please visit KYTC’s SAFERoad Solutions web page.

DCD

If you’re a longtime reader of this newsletter, you’ve read about double-crossover diamond (DCD) interchanges before, but they are still a new addition to Kentucky interchanges. A DCD is often built at a highway interchange to improve safety and congestion. In this design, traffic crosses over to the left side of the roadway briefly between two traffic signals. As the vehicles exit the interchange, they return to the right side of the road.

DCDs might look a little strange, but they’re safer than normal interchanges because they allow vehicles to turn left onto and off of freeway ramps without stopping or crossing opposing lanes of traffic. They also reduce wrong-way ramp entries and speeds, so any crashes that might occur are often less severe.

When you’re driving through a DCD, follow the lane markings and traffic signals to cross over to the left side of the road, travel through the intersection, and then cross back over to the right side of the main road. There are multiple marked crosswalks for pedestrians to travel through the interchange.

In Northern Kentucky, there are DCDs at Graves Road and I-275, Mt. Zion Road and I-75, and Richwood Road and I-75.

SPUI

Last year we opened a single-point urban interchange (SPUI) at Richwood Road and US 25. If you recall, a SPUI is a highway interchange where a single signalized intersection controls the traffic flow. The design allows for vehicles turning left and coming from opposite directions to turn at the same time, without crossing paths. This improves safety by decreasing the number of places where vehicles intersect, in turn decreasing the opportunity for collisions.

In a traditional interchange, there are two traffic signals. In a SPUI, there’s only one, and it’s part of either an overpass or an underpass. In the case of the Richwood Road and Dixie Highway SPUI, the signals are located at the underpass, with traffic flowing freely on Dixie Highway above. This improves efficiency by increasing “green light” times and reducing delays for drivers.

Because left turns occur simultaneously, more vehicles can travel through the intersection, increasing capacity. SPUIs also have a smaller footprint than conventional interchanges, which reduces the overall impact.

In addition to the SPUI at Dixie Highway and Richwood Road, another SPUI is located at KY 18 (Burlington Pike) and KY 237 (North Bend Road/Camp Ernst Road).

Roundabouts

You’re probably more familiar with roundabouts, but they’re becoming increasingly popular, so it’s always good to have a refresher! Roundabouts are one-way circular intersections where traffic moves counterclockwise. They don’t have traffic signals or stop signs, which allows for continuous traffic flow and increased vehicle capacity.

When approaching a roundabout, don’t forget to watch for and yield to pedestrians and bicyclists who might be in the crosswalk. When you’re looking to enter the roundabout, you will need to yield to the vehicles in the circle that are approaching from the left. You can enter the roundabout once there is a safe space to do so. Finally, once you’re in the roundabout, you have the right-of-way and should continue moving around the circle until you reach your exit.

Roundabouts save time for motorists, since traffic is continuous, and drivers can experience fewer stops. They also save taxpayer dollars because there is no equipment to maintain and power.

There are many examples of roundabouts in Northern Kentucky, and you’ve probably travelled through them yourself. Two new roundabouts were recently opened on KY 536 (Mt. Zion Road) between Dixie Highway and KY 1303 (Bristow Road).

These are just a few of the many traffic patterns covered on KYTC’s SAFERoad Solutions web page. There you can find information on Continuous Green T Intersections, Jughandles, Turbo Roundabouts, and Restricted Crossing U-Turns, just to name a few. As always, KYTC works hard to provide a safe, efficient, environmentally sound and fiscally responsible transportation system. 

Project Updates

Construction is continuing on many projects in Northern Kentucky. In fact, the Mineola Pike Widening project has reached substantial completion! Keep an eye out for next month’s newsletter, as there will be more details and photos from the Mineola Pike project, as well as some big announcements on the KY 236 (Donaldson Highway) project, and other projects around Northern Kentucky!