The use of roundabouts to control intersections instead of traffic signals or stop signs continues to grow in the United States. The first modern roundabout in this country was constructed in Nevada in 1990, there are over 4,800 today. Roundabout growth is a result of a number of factors, but three main advantages have fueled their growth.
1. First, they have a significantly superior safety history when compared to signalized intersections. In Golden we compiled before and after data on roundabouts. When we switched South Golden Road to roundabouts, our accidents dropped 67%, and injury accidents were reduced by over 99%. This makes sense because traffic speeds in roundabouts are 15 to 20 mph.
2. Second, they provide significant pedestrian safety benefits. Research completed by North Carolina State University for the US Department of Transportation cited a 50% reduction in accidents, which makes sense because a roundabout has 8 points of pedestrian conflict with cars and a typical signalized intersection has 16. Again the data clearly shows that injuries are reduced because of slower speeds. A pedestrian has an 85 percent chance of death when involved in a motor/vehicle collision at 40 mph, a 45 percent chance of death at 30 mph, and a 5 percent chance of death at 20 mph.
3. Finally, roundabouts have more capacity than a signalized intersection. This reduces delay, idling and pollution. This means even though you are driving slower, on average you spend less time because you are never waiting for a light to change.
Two Frequently Asked Questions about Roundabouts
- Why does the city put landscape, statues or other things in the center of roundabout that restricts sight distance to the other side of the roundabout? One of the important issues in designing roundabouts is to control entry speed, sight distance is provided to the left at entry so vehicles in the roundabout can be seen, but sight distance through the roundabout is limited which reduces speed and force drivers to look for vehicles that they need to yield to on the left at entry.
- In some roundabouts there is actually a slight curve to the left before bending to the right at entry. Without that curve, entry would be smoother, so why not remove it? That small curve is designed to control entry speed, particularly in what are referred to as mini-roundabouts, to insure sufficient entry deflection. It actually aligns the driver’s vision to the left as they approach, and tighten the entry radius which reduces entry speed. This is an evolution in design guidelines from the Federal Highway Administration, and that deflection is not common in older roundabouts. You can see the deflection in these three newer roundabouts, on Heritage Road, in Jefferson County and in Grand Junction.
Features of the new roundabout at 19th and Elm Street
2. Visit the Xcel website
Other Street Division Maintenance Duties:
Signage – damage, graffiti removal (new signage is performed by the Engineering Division)
Guardrail / Barricades
Edge of Road