Location: Tucson, AZ
Client: Pima County DOT
Pima County Department of Transportation (PCDOT) has rebuilt the Veterans Memorial Overpass in Tucson , Arizona. The contracting company performing the construction submitted a value-engineering (VE) proposal to replace all Cast-in-Place (CIP) retaining walls on the Veterans Memorial Overpass (VMO) with Mechanically Stabilized Earth (MSE) walls. PCDOT retained NCSG to assist with the evaluation of the VE proposal.
As part of this evaluation, NCS’ scope of work included the following tasks:
The Veterans Memorial Overpass project includes a single-span bridge over the Tucson Diversion Channel, and a multi-span bridge over a divided highway and Union Pacific Railroad tracks. For the abutments for the multi-span bridge spread footings on top of MSE walls were used. The North and South abutments consist of spread footings on top of 25-ft and 35-ft high MSE walls, respectively. Both abutments are 150 ft long. The bridge consists of simply supported AASHTO Type III girders on elastomeric bearing pads resting on an abutment footing. The bridge footing at each abutment is 10.75 ft wide and 10.2 ft high. Clearance between the back of the coping and the toe of the footing is 6 in. Approach slabs were not used. The length of reinforcements was equal to the height of the abutment. Reinforced fill was a select granular fill, in accordance with AASHTO/FHWA requirements. Ribbed steel reinforcing strips were used for soil reinforcements, with 5-ft tall x 10-ft wide precast concrete segmental panels.
This project was monitored with over 500 survey points. Settlements of less than 1 in., primarily occurring during construction, were measured. No noticeable post-construction settlement has been observed
This project has been constructed and is in service.