The North Cattlemen Road Extension in Sarasota County, FL, is a $20 million transportation improvement project that connects University Parkway at its north end with Fruitville Road to the south. With north and south ends of the roadway now joined, local traffic can bypass Interstate 75, and have easier access to some of the area’s most desirable commercial, recreational and sporting facilities. An existing two-lane road was transformed into a four-lane divided roadway, and the four divided lanes were extended further north for another 1.75 miles (2.8 km). Funds supplied by the federal government were administered through the Florida Department of Transportation (FDOT) on behalf of Sarasota County. The project encompasses the road, a 96-foot (29.3 m) bridge on Cattlemen Road to Center Island on a 400-acre (162 hectacres) lake, excavation and reconfiguration of a 50-acre (20 hectacres) lake, and two additional bridges to a new island built as part of the road’s program. But there is also a parallel project underway near the Cattlemen Road site.
Sarasota County is creating an extensive recreational boating and rowing competition center at the Nathan Benderson Park. The Cattlemen Road Extension project included realigning a land bridge about 300 feet (91.4 m) away from its original location.The move was necessary to expand the rowing area of the park’s main lake and accommodate 2,000-meter (6,561-ft) Olympic-class rowing events, with Sarasota’s sights set on hosting the 2017 World Rowing Championships. “Initially, there were two separate retention ponds detailed on either side of a faux bridge,” said Alex Boudreau, civil engineer and project manager for Sarasota County Public Works Division.“Faux,” because it was designed as a causeway to look like a bridge, even though the stormwater ponds were not actually connected hydraulically. But the aesthetic decision was later made to change that feature to a single body of water flowing under a bridge. In addition, an idea took hold to build an island in the large lake with two span bridges, at east and west ends of the new island. These are some of the changes that contributed to the cost increase from the original estimate of $14.5 million. Soon after construction commenced, the general contractor took another look at the precast mechanically stabilized earth (MSE) retaining walls.
In consultation with the design builder, the block producer and the licensor, senior project engineer with Prince Contracting Company Thomas Hill said, “We evaluated a segmental block retaining wall system design and construction process as an alternative to conventional MSE retaining wall construction.” “At that time, the FDOT was in the process of adding the segmental block retaining wall systems to its innovative designs list. After researching and reviewing the new product, Prince proposed the use of the segmental block retaining walls as an alternative to the conventional MSE retaining walls,” Hill added. The contractor convinced Sarasota County and the FDOT to use the new segmental block retaining wall system. Boudreau says the SRW walls turned out to be much more cost effective. “The modular masonry retaining walls were less costly upfront including installation and created a beautiful wall that offered flexibility—the wall could be installed at the same time other parts of the project were being built,” he said, and it had the same strength characteristics of precast. He points out that the decision to add two more bridges influenced the selection of segmental retaining walls. It was a given that the look of all three bridges needed to be cohesive, but there would be a minimum of a one month delay for each precast panel order.
Instead, the SRW units could be delivered quickly and installed. Hill says, “The segmental block retaining wall system allowed Prince to speed up the project by significantly cutting the shop drawing review process time frame, as well as shortening the time of production of the blocks. Additionally, the construction process of the segmental block retaining walls allows the contractor to get more daily production, as compared to conventional MSE retaining walls, on longer walls.” There was yet another advantage, according to Boudreau— maintenance. The SRW system would come integrally colored and not require an applied finish. Precast panels would need to be painted, and frequently repainted. “The paint is decorative, sure,” he said, “but it is also required to seal the concrete so that moisture doesn’t penetrate and cause the steel components in the system to rust and the rust to show on the surface. In the SRW concrete block system the reinforcement and the individual units are held together with synthetic rods. So, there is nothing to rust,” he says. Switching to SRW units was also a cost savings for the owner thanks to the ability to use onsite fill material as opposed to importing expensive select fill. The material available was a well-graded, coarse aggregate with less than 15 percent of fines (material finer than the #200 sieve) with a plasticity index less than 6 percent, but it didn’t meet the stringent electrochemical requirements to be used with metallic reinforcement. The project totaled 50,000 square feet (4645 m2 ) of facing in four bridges with a maximum height of 18 feet (5.5 m). Once the walls were completed, erosion protection was added to the front of the walls to avoid scour due to the water moving in front. While the park and rowing center are still under construction, this 2.75-mile (4.4 km) roadway improvement project was completed in June 2013.The SRW portion was finished in January 2013 and the road opened May 2013. All in all, the Cattlemen Road Extension project was a success, says Boudreau. It moves cars through the area smoothly, relieves congestion on I-75, and is beautiful to look at. Boudreau says he and a lot of people in the area take their families on drives along the Cattlemen Road Extension, even before the park has been completed.