East Main Street is a major cross-town corridor carrying 20,000 vehicles per day with a consistent influx and outflow from the US 53 interchange — the primary north-south corridor connecting the Onalaska-La Crosse metropolitan area to the far reaches of northwestern Wisconsin and Minnesota. Green Coulee road supports traffic from 400 homes along a single-access residential road.
The intersection of East Main Street and Green Coulee Road was formerly stop-controlled, suffering a rapidly diminishing ability to safely and efficiently handle the steady increase in traffic. This led to long wait times at the Green Coulee Road stop sign and undue congestion, resulting in risky decision making by drivers and subsequent vehicle crashes. Residents and businesses demanded action.
Yet it is no small feat to satisfy the oftentimes competing interests of local commerce, large retail and the Wisconsin Department of Transportation (WisDOT), all within the tight constraints of the project site at hand. So, when a local Kwik Trip and the WisDOT came to odds over uncontrolled driveway access, MSA engineers knew a new two-lane roundabout would be the optimal option for all parties and the safest long-term solution. Yet there simply wasn’t enough room for the roundabout within the existing footprint and very few options without eating into prime real estate.
MSA transportation engineers devised an innovative means to create space without adversely impacting key local businesses. The answer involved connecting two existing large dual box culverts with a new retaining wall. This design allowed the structures to remain in place while still supporting proper channel flow and capacity for a local stream beneath the two roadways. It also provided the means to fill in the portion of the channel behind the wall and expand the intersection footprint, gaining an indispensable 3,200 square feet of space in which to construct the envisioned two-lane roundabout.
The roundabout design posed a number of additional challenges, including limited right of way, stream channel needs and business driveway access. MSA explored several iterations of the horizontal design, pulling and stretching the roundabout shape from its traditional circle to a more oblong form, being mindful of precise positioning and critical design parameters such as entry deflection, speed control, path overlap, and large truck accommodations.
The result immensely improves safety and efficiency at a busy regional intersection, slows vehicular speeds, reduces vehicle emissions, implements accessible two-stage crossings for pedestrians and delivers intuitive, secure access to businesses throughout, all boosting the well-being of local residents, guests and the local economy. It is a shining example of inventive, outside-the-box thinking and public-private-regulatory agency coordination.
The East Main Street and Green Coulee Road Roundabout project was chosen to receive a 2023 Engineering Excellence State Finalist Award from the American Council of Engineering Companies (ACEC) of Wisconsin.
This project was also selected by the American Public Works Association Wisconsin Chapter to receive a 2023 Project of the Year Award in the Small Cities/Rural Communities – Transportation category.