Florida's Turnpike - Designing Veterans Expressway Improvements

Florida's Turnpike - Designing Veterans Expressway Improvements


Veterans Expressway Improvements
Reinforced Earth Product in Field
Location: 
Tampa, FL
Owner: 
Florida Department of Transportation
Subcontractor: 
Bonn-J Contracting Inc.

Introduction

Construction on the $380 million Veterans Expressway widening project started in summer 2013. When the project is completed, two lanes will be added in each direction: one an express lane, the other a general use toll lane. The project includes 65 Reinforced Earth® MSE walls, totaling 648,420 square feet of wall facing (11 football fields).

Challenges

Reduce excavation and shoring
Normal reinforcing strip length is 70% of the height of the MSE wall. Creating this width of excavated space would have required the contractors to install deep sheet pile walls. A customized design of the wall section was developed, using less space and requiring less excavation. The contractors were able to eliminate the expensive sheet pile walls, and where a supported excavation was still required, they used considerably lower height, less expensive soldier pile and lagging walls instead.

Existing MSE walls
Original project requirements indicated that new MSE walls were to be built in front of existing walls, and because of the lack of space for a 70% footprint, they were to be "tied" together. However, making a mechanical connection to an existing wall can create unwanted and unpredictable tension loads in both structures if there were to be any differential settlement. Therefore, RECo designed the proposed walls with a special typical section in order to be built in front of the existing MSE walls as an independent structure.

Abutment geometry
Widening adjacent to existing structures presented another complexity at bridges. Florida supports its bridges on piles placed behind the facing of the MSE walls. The reinforcing strip configurations were designed to allow them to be skewed horizontally to avoid the piles, with panels in that area specially detailed and fabricated to match the abutment geometry, top of wall slope, and the corner where the wall wraps around the abutment.

Foundation sinkhole
In a case where a proposed wall was to adjoin to the end of an existing wall, there was a sinkhole located below the foundation. The existing wall was originally designed with a geogrid load transfer platform at the bottom of the wall. This solution was used for the new wall as well, to reduce concentrated loads from the MSE wall above the sinkhole. In addition, lightweight foam concrete fill was used for the select backfill to lower the applied bearing pressure of the wall above the sinkhole.

Advantages
Customizing wall designs to the specific site conditions significantly reduced both the excavation volume and the type and quantity of excavation support, saving considerable time and money.