The Delhi Street/N. Grandview Avenue/Grace Street intersection was upgraded to an urban, single-lane roundabout in August 2016.
As more traffic was using the previous intersection, the delay at the stop signs were expected to continue to increase, causing increased driver frustration and potentially more crashes.
The goal of this intersection improvement project is to provide a safer and more efficient intersection.
The intersection’s existing pavement was in need of replacement.
This project will also provide improved pavement throughout the intersection.
Why a roundabout and not a signal?
It is very difficult to provide acceptable traffic operations through the installation of traffic signals at a five-legged intersections like this location. Because most of the intersection’s traffic was on N. Grandview Avenue and Delhi Street, any time dedicated to servicing Grace Street traffic would have caused unnecessary delays for the rest of the vehicles using the intersection. The roundabout at this location will provide excellent operations for the next 20-30 years.
Roundabouts are statistically safer than traffic signals. A trade-off occurs between T-bone collisions that occur when a driver attempts to “beat” a red light at an intersection with signals versus low-speed, side-swipe collisions at a roundabout.
With a traffic signal, delays are present 24-hours a day when a driver encounters a red light. At a roundabout, less delay occurs, especially at off-peak hours, due to the yield condition. This aspect is also a benefit to the environment since fewer vehicle emissions are placed into the air by vehicles waiting at red lights.
Cost and Funding
The total cost of this intersection improvement project is estimated at $845,000 of which $500,000 will be funded by the Iowa DOT Traffic Safety Improvement Grant, and the remainder funded by the City of Dubuque. This project funding was approved as part of the City's fiscal year 2016 budget process.