Location: Tucson, AZ Client: Pima County DOT Status: Completed
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:
Setup the criteria for MSE wall design and modify the ADOT specification as necessary.
Review of the VE design concepts including checking MSE wall design calculations and drawings, providing comments and/or recommendations, and comment/recommendation resolution.
Site meetings during VE evaluation.
Construction Inspector Training
Field support during construction
Setup of instrumentation plan and reduction of data
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.
A view of the North abutment and two of the piers on the VMO project after placement of the girders.
NCS was awarded the 2005 Marvin M. Black, Excellence in Partnering Award by the Associated General Contractors of America for our work on the Veterans Memorial Overpass Improvement Project.
A special tour given by NCS and Pima County to members of ADOT on May 5, 2005. From left to right are Pete Anderson, Ed Nowatzki, Greg Gentsch, Doug Forstie, Dan Lance, Tom Kilargis, Perry Powell, Norm Wetz, Shawn Farahzadi, Naresh Samtani, Bill Hurguy, Steve Haire, Mike Myers, and J.J. Liu.
Naresh Samtani of NCS receiving a Certificate of Appreciation for work on the Veteran's Memorial Overpass (VMO) project from Ramon Valadez of the Pima County Board of Supervisors.
Naresh Samtani and Ed Nowatzki of NCS receiving a Certificate of Appreciation for work on the Veteran's Memorial Overpass (VMO) project from Ramon Valadez of the Pima County Board of Supervisors.
Naresh Samtani and Ed Nowatzki of NCS receiving a Certificate of Appreciation for work on the Veteran's Memorial Overpass (VMO) project from Ramon Valadez of the Pima County Board of Supervisors.
A Certificate of Appreciation received by NCS for work on the Veteran's Memorial Overpass (VMO) project.
A view of the North abutment of the VMO project after placement of the girders.
A view of the North abutment of the VMO project after placement of the girders.
An example of lightweight compaction equipment to be used within 3 ft. behind the wall face.
Mr. Samtani indicating the correct placement of a connection bolt between a reinforcing strip and an MSE wall facing panel.
Mr. Samtani showing MSE wall construction in progress.
The spread footing atop the MSE Wall north abutment on the VMO project.
A view from the corner of the north abutment on the VMO project.
A view from the top of the north abutment on the VMO project. This is the location where the footing will be constructed.
This photo shows a wider view of the MSE Wall north abutment, the spread footing on top of the abutment, and the closest piers for the VMO project.
Placing MSE wall facing panels on the VMO Project.
Placing MSE wall facing panels on the VMO Project.
View of one of the approach walls on the VMO project.
The audience for a presentation and tour given by Mr. Samtani on MSE walls, and the Veterans Memorial Overpass project.
Mr. Samtani presenting on MSE walls, and the Veterans Memorial Overpass project.
A tour group sponsored by the ASCE Young Members Forum (Southern Arizona Branch) guided by Mr. Samtani for MSE walls and the Veterans Memorial Overpass project.
Mr. Samtani talking about an MSE wall facing panel for a tour of the Veterans Memorial Overpass project.
An excellent example of two different types of compaction equipment needed in the construction of MSE walls. The lightweight equipment is used within 3 ft of the face of the wall, and the heavy equipment is used behind as seen on the Veterans Memorial Overpass project.
An inspector checking the compaction during MSE wall construction on the Veterans Memorial Overpass project.
Value engineered alternative
Multi-span bridge over divided highway and railroad tracks
Abutment consisting of spread footings on top of MSE walls
No approach slabs
Became the basis for design guidance and example problem for true bridge abutments in FHWA’s 2009 MSE wall manual.
We use cookies to ensure that we give you the best viewing experience on our website. By continuing to use this website you are consenting to our use of cookies, Privacy Policy and Terms of Service.OK, Got it!
