In Shipshewana, Indiana, Burgess and Niple (B&N) developed long-term, cost-saving, innovative solutions to the roadway settlement, flooding and rutting caused by Amish horses and buggies in a major tourism thoroughfare. Working with the Indiana Department of Transportation, the B&N team led the design of a 2.5-mile roadway rehabilitation on SR 5, roadway reconstruction in the Page Ditch marsh and a bridge over Page Ditch.
Project Challenges
There were several challenges this project presented. Shipshewana and the surrounding areas have a large Amish community; along SR 5, horse and buggy traffic heavily rutted the existing pavement. In the Page Ditch marsh, consistent flooding has caused a 4-inch roadway settlement on SR 5 every year. When the ditch floods, water consumes the road, overtop and underneath, slowly eroding the subgrade material.
In addition, due to the high volume of automobile traffic from tourists and buggy traffic on SR 5, maintenance of traffic and public outreach posed significant challenges to the project.
Innovative Solutions
Partial-Depth Cold-in-Place Recycling (CIR) was used to extend the life of the existing pavement that was heavily rutted by horse and buggy traffic. By mixing the reused asphalt pavement with cement, the pavement is now durable enough to resist rutting caused by the Amish horseshoes and steel buggy wheels. The CIR was then capped with a stone-matrix asphalt (SMA) overlay to reinforce the pavement. The use of partial-depth CIR was new to Indiana and INDOT, offering a more sustainable solution to pavement preservation because it requires less material, less trucking, and less material is deposited into landfills.
Lightweight Cellular Concrete was used to stop the 4-inch annual roadway settlement. Mixed onsite, it was designed to float in the low-strength peat material. The roadway over the lightweight cellular concrete was reinforced PCC pavement, designed to add enough weight to provide a neutral buoyancy of the lightweight concrete and enough strength to bridge any deflections caused by the settlement of the peat. Steel-encased concrete piles support the bridge through the 40 feet of peat material, with a donut seal to embed the pile as it is embedded in a layer of sand with a pressurized artesian aquafer within it. The use of floating concrete was also new to Indiana and INDOT and had never been done in this application before, providing a new cost-effective and long-term solution to bridging low-strength soils.
Maintenance of Traffic had to account for Amish pedestrians and bicyclists. When reviewing nearby county and state roads, the team recommended an adjacent county road as a detour for vehicle traffic during construction. But because it was an additional five miles away, it wasn't a viable option for the Amish who walk and bike in and out of Shipshewana. During construction, the team built a pedestrian bridge next to SR 5 over Page Ditch to ensure local access into town.
Public Outreach was another project challenge. Typical approaches that rely on digital media could not be used due to the lack of connectivity to those resources in the Amish community. B&N assisted INDOT with scheduling face-to-face meetings with Amish leaders to ensure everyone was on the same page and understood the project.
Completed on Schedule and Below Budget
The project team's use of partial-depth CIR and lightweight cellular concrete helped keep this project on schedule and $5 million under budget. The use of CIR allowed the team to reuse the existing pavement materials, which cut transport and disposal costs, and the production rate of CIR is incredibly high compared to traditional paving. Using lightweight cellular concrete reduced excavating costs because the team was able to excavate and spray the concrete to backfill in just three days. The excavation only needed to remove enough peat material to offset the weight of the new roadway pavement, instead of completely removing the entire depth of peat and backfilling; as is the traditional method.