This year, the City has begun constructing Cape Girardeau’s fourth roundabout at the intersection of Independence Street, East Rodney Drive and Gordonville Road. The new roundabout is scheduled to be completed by the end of 2016, weather permitting.
Funding for this project comes from the Transportation Trust Fund’s (TTF) fourth installment, approved by voters in 2010. TTF-4 allocated funding to the improvement of traffic flow at the Independence Street/Gordonville Road/East Rodney Drive intersection. The roundabout was selected as the best option to improve traffic flow and congestion at the busy intersection.
The City originally allotted $250,000 for the project through TTF funding, however state-issued funding made the project possible. Small Urban Surface Transportation Program funding covers 80 percent of the project, and the City funds the rest with the originally-allotted TTF funding. Total project cost, including the City’s funding portion and the Small Urban Surface Transportation Program funding, is $741,000.
The roundabout will be a single lane, similar to the one at the Fountain Street and Morgan Oak Street intersection by the River Campus, and will be approximately the same size, having an outer diameter of 135 feet and an 18 feet wide lane. This roundabout will be significantly larger than the one at Gordonville Road and Silver Springs Road.
“It’s a balancing act, figuring out the proper lane width,” said Tim Richmond, the City of Cape Girardeau Engineer managing the project. “We have to make the lane small enough for the right amount of deflection upon entering, but also wide enough to accommodate larger trucks.”
The roundabout will have a speed limit of 15 miles per hour, and is designed to handle the amount of cars passing through the intersection during peak morning and evening hours, allowing for passage of approximately 1,100 to 1,400 vehicles per hour. Once complete, officials estimate that the roundabout intersection’s traffic will be about 15,000 vehicles per day, with the potential to accommodate up to 25,000 vehicles per day.
The new roundabout is expected to hold the same safety standards as the existing four-way stop intersection, but allows for more efficient travel flow and allows safer crossing for pedestrians.
“If we installed a light at this intersection, the environment would completely change,” Richmond said. “The high-speed environment that occurs at traffic light intersections would be completely different than what we have now.”
A roundabout is preferable to a four-way stop or traffic light at the busiest intersections because traffic is able to continuously flow through the intersection, as opposed to waiting for a light to change or for a turn at the stop sign. Therefore, roundabouts process vehicles through a high-traffic intersection more efficiently than a stop sign or traffic light.
VIDEO: Mythbusters test a four-way stop v. a roundabout
The new roundabout’s construction will begin this summer, and the closing of the intersection isn’t scheduled until after the SEMO District Fair in September. Once closed, the contractor has a maximum of 60 days to reopen the road.
When the City installed the roundabout on Lexington the project was able to be completed in halves, meaning that the road didn’t have to be closed. That is not the case with the new Independence roundabout.
“This roundabout is different,” said City Engineer Casey Brunke. “As you’re coming from the Kingshighway/K-Mart area, we have to raise that section of the street by approximately five feet, so we can’t keep it open.”
The road must be raised in order to create a flatter section of driving space able to accommodate the roundabout’s size and gain necessary sight distance.
Brunke added that there is work that can be done without closing the road, including the new driveway for the First Church of the Nazarene.
The single-lane roundabout will have a 63-foot center island that will be filled with landscaping rock, allowing for vegetative landscaping or public art possibilities in the future. The roundabout will be made of concrete, with a darker-colored concrete being used for the interior and exterior truck aprons that allow for smoother passage of semi-trucks and emergency vehicles.
A project to improve traffic flow on Independence Street between East Rodney Drive and Caruthers Street will be completed under TTF-5, and the improvements will work with roundabout to improve the functionality of the road.
Not sold on the new roundabout? Here are more roundabout fun facts:
- According to Sergeant Kevin Orr of the Cape Girardeau Police Department, since the installation of the roundabout on Lexington Avenue and Route W/Kingsway in 2013, the overall number of accidents has stayed roughly the same, but accident severity has decreased. Since roundabouts force drivers to drive at slow speeds the severity of accidents is typically much lower than accidents that occur at stop lights, which allow for faster speeds. Most accidents in roundabouts occur due to a failure to yield upon entering.
- A four-way intersection with a stop light has about 20 conflict points where accidents may occur, while a roundabout has only eight (Missouri Department of Transportation).
- Roundabout installation has been found to reduce carbon monoxide emissions 15 to 45 percent and decrease vehicle delays 89 percent (Insurance Institute of Highway Safety).
- Landscaping in the center island of a roundabout can improve the appearance of an area, break the glare of oncoming traffic, promote lower speeds, and discourage drivers from driving over and straight through an intersection (Federal Highway Association Department of Transportation.)