Noted transportation author and UC-Berkeley professor Robert Cervero once wrote, “Planning of the automobile city focuses on saving time. Planning for the accessible city, on the other hand, focuses on time well spent.”
This statement stands well as a philosophical and operational treatise for the planners of the USH 18/151 Verona Road Reconstruction Project (Stage 1) in Madison, Wis., the Roads & Bridges top road project of 2017.
“This is such a sensitive area,” John Vesperman, Southwest Region megaproject chief for the Wisconsin Department of Transportation (WisDOT), told Roads & Bridges. “This project was squeezed into an urban area between an environmental justice neighborhood, so connectivity between both sides of the project was so important. For folks to see that was crucial. There’s a lot of walking and biking that goes on throughout the whole city of Madison. Throw in the economically disadvantaged area in the project zone, with folks who don’t have access to other forms of transportation, and planning for multimodal was a key concern.”
The project limits describe the complete reconstruction of 2 miles of USH 12/14 (the “Beltline”) and the reconstruction of .75 miles of USH 18/151 (Verona Road), including the complete reconstruction of the interchange at USH 12/14/18/151 from a diamond interchange to a single-point urban interchange. Alongside concerns about congestion relief, mobility improvements for the community were paramount.
“I remember when we were first starting this project,” Vesperman said, “I saw a few wheelchair-bound people going down the actual road because there were literally no sidewalks in the area to accommodate them for going to the market and so forth. Well, now those people are going to be safer, and it helps with our traffic congestion concerns.”
A good grade
“South of the Beltline, there was an at-grade intersection that was failing in both congestion and safety,” Chris Frederick, WisDOT construction project manager, told Roads & Bridges. “The solution the design team came up with was for a jug handle and a roundabout underneath Verona Road.”
The existing intersection of Verona Road and Summit Road, which had been queuing traffic all the way back to the Beltline, was eliminated. The design team evaluated several alternatives and ultimately recommended a jug-handle-style intersection with right-in, right-out access and a new grade-separated roundabout crossing for left and through movements. While the jug handle eliminated the signal, the installation of the roundabout kept communities on either side of Verona Road connected.
“There was more grade available there,” Joe Bunker, project manager for Strand Associates Inc., told Roads & Bridges, “so we could get the roundabout underneath the bridges and create a grade separation. We were able to maintain community connectivity while still having a benefit in traffic operations and safety. There were quite a few T-bone accidents at that intersection that the roundabout eliminated.”
The unique aspect of this alternative was Verona Road spanning 278 ft over the multilane roundabout without the use of traditional piers. A pair of steel straddle bent bridges were employed using a single pier column in the central island of the roundabout and pier columns on either side, well outside the bridge footprint. The outside piers straddle the roundabout.
The two span structures use 54-in. steel plate girders (eight girder lines on each structure) with spans of 148 ft and 130 ft. The center pier cap consists of a steel bent (the first of its kind in Wisconsin) 6 ft tall by 4 ft wide and 193 ft long to span the legs of the roundabout. The bent integrally supports the girder lines.
“We had very limited closures, thankfully,” Mark Vesperman, WisDOT design project manager, said. “All told, we only had closures for about 12 nights—and this is for a project that began in 2013.”
Seeing the SPUI
In order to visualize just how drastic a change designers were planning in replacing the existing diamond interchange at the intersection of Verona Road and the Beltline with a single-point urban interchange (SPUI), a 3-D model of the area was created.
“The public didn’t really know how a single-point interchange would function until they saw the rendering video,” Bunker said, “but then they could see and understand how the signals and traffic flow would work. We had very limited questions from the public because of the rendering.”
Placing the SPUI beneath a major roadway (the Beltline) offered several significant challenges, including:
- Location and sight lines of the traffic signals;
- Bridge span lengths and bridge economics;
- Pedestrian and bicycle movements; and
- Construction staging and maintenance of traffic.
The benefits, however, outweighed those challenges, including the ability to move large volumes of traffic through a limited right-of-way, eliminating a full intersection, and reducing the number of conflict points at the interchange, thus reducing the probability of crashes and associated costs. Greater capacity and operational efficiency is achieved through higher average travel speeds, fewer signal phases, increased signal cycle length and greater green time for nearly all movements, reducing traveler delay and vehicle emissions.
Keeping the flow
“During the entire project, we worked on the diversion network to improve those roads and intersections,” Frederick said. “Eight different intersections in all, from installing signals to lengthening turn lanes. It really just depended on the intersection. We also added adaptive signal controllers on the primary diversionary route, Fish Hatchery Road, and worked with local goverment on the install. We knew people would divert to that corridor. Those signals are now permanent infrastructure.”
The success of WisDOT’s traffic management protocols Frederick attributed to diligence and foresight: “We did quite a bit of analysis beforehand, and during construction we maintained two through lanes on Verona Road and the Beltline at all times, during all stages. Only the overnights restricted that.”
Crews are now banging away at Stage 2, which will go through 2020.
Project: USH 18/151 (Verona Road) Stage 1 Reconstruction
Location: Madison, Wis.
Owner: Wisconsin Department of Transportation
Designers: Strand Associates Inc. (prime), along with consulting team
Contractors: Zenith Tech Inc. (let 1); Industrial Steel Construction Inc. (let 2); Hoffman Construction Co. (lets 3/4)
Cost: $107 million
Length: 2.75 miles
Completion Date: November 2016