ACTT Workshop: Louisiana
December 15-17, 2003, West Monroe, Louisiana
Chapter 2: Project Details
2.1 Corridor Description
The elevated section in Monroe was constructed under four separate contracts; the main Ouachita River bridge span, elevated approach sections on each side of the river, and two contracts linking the ground roadways to bridge approaches. Construction began on these projects in 1958, with final acceptance of the last project being made in 1964. The elevated approach sections of the Interstate consist of the two independent steel girder simple span bridges, erected on portland cement concrete (PCC) caps, columns, and pile supported footings. The typical deck section is an 18-cm (7-in) reinforced PCC slab with a wheel curb barrier rail. The structures are aligned such that the raised section of the barrier on the westbound roadway serves as the common median rail for the eastbound roadway. The western approach and main span roadways are typically 12 m (40 ft, 3 lanes) in width; however, as the route crosses the river into Monroe the typical roadway narrows to 8 m (28 ft, 2 lanes) in each direction.
The elevated section of I-20 has remained in service with routine maintenance and only one major rehabilitation since 1965. The deck sections constructed under the elevated approach contract exhibited surface distresses in the late 1970s. A project to overlay the west approach section was performed in 1980-81. A 600-m (2,000 linear ft) section of the deck structure was scarified and patched, the joints modified, and a 3.8 cm (1.5 in) latex-modified concrete overlay placed over the prepared surface. Traffic was maintained in a single lane while work commenced, with little loss in level of service of traffic flow. Within the past few years, surface repairs and required maintenance performed on the deck have been extensive. The 1980 overlay section has begun to de-bond as it nears a 25-year service life. Maintenance is generally performed on the weekends to minimize disruption of traffic.
As reconstruction or renovation of the Interstate System became a priority to FHWA and LDOTD in the mid 1980s, continued bridge rehabilitation projects fell victim to the need to re-surface pavement sections that experienced an accelerated decline in serviceability. When scoping the I-20 bridge rehabilitation project for initial design, it was realized that current funding levels could not finance a project of the magnitude envisioned. Due to the need for repeated maintenance work over the eastern elevated approach, the District identified the area of greatest need and worked with its Bridge Design office to secure funding for the deck rehabilitation project identified as State Project 451-06-0121. Further investigations for unsound areas confirmed the scope of the current project. The proposed work is to patch structurally deficient areas of the deck, resurface the mainline and associated ramp roadways, and to modify the existing brush curb bridge rails into a more modern barrier design.
2.2 ACTT Goals
Upon selection of the project for the ACTT Workshop, the District developed the following goals and objectives for the project:
- Reduce construction time.
- Maintain traffic flow with minimal disruption.
- Produce a quality project with minimal long-term maintenance needs.
- Maintain a safe work zone.
- Maintain access to emergency facilities.
- Provide a model for future projects.
2.3 Project Challenges
Traffic counts indicate the current average daily traffic (ADT) on the structure to be approximately 95,000 vehicles. Within the Monroe/West Monroe area, only two other river crossings are available: both are located upstream of I-20. The two-lane Desiard Street (Endom) Bridge carries approximately 11,000 vehicles per day and the approach routes are not under the jurisdiction of LDOTD. The four-lane US 80 (Louisville Avenue) bridge has an ADT of 40,000 and is the principal east-west route through Monroe. Both of these bridges are movable spans and must open on demand to river traffic. Neither bridge was considered an alternate route for Interstate traffic. Other river crossings in the region require significant time and mileage to access and are not viable detours.
LDOTD's current guideline for traffic control through construction zones is to limit queue lengths to no more than a 30-minute delay. Analysis by the District Traffic Operations section indicates two through lanes of Interstate traffic must remain in service during daylight hours to avoid significant delay times. As sections of the roadways to be renovated are only two lanes in width, either a detour route or a compressed work time schedule must be utilized to maintain traffic flow. Calypso Street and Layton Avenue, which parallel the structure, may be used as detour routes, subject to limitations. Calypso Street on the north side of I-20 is a city street and can only be closed to local traffic on the weekends. The District worked with FHWA to secure partial funding of the City's current project to reconstruct Calypso Street in return for its use as a detour route during the deck rehabilitation project. Layton Avenue is located south of the bridge and cannot close to cross traffic at the business US-165 intersections. The ramps associated with the project are the entrance and exit ramps to downtown Monroe that access the City Hall/Police complex, the Civic Center, and a major hospital, St. Francis Medical Center.
Due to the impact of the project on local and Interstate traffic patterns, the District's chief goal is to minimize the amount of time the roadway is under construction. Traffic analysis indicates most work will need to be performed at night or on weekends. As the Calypso Street detour route is only available on weekends, mainline westbound construction may only occur from Friday night to Monday morning. The contractor must restore the two lanes of Interstate traffic to the existing roadway before weekday peak morning traffic.
2.3.3 Limited Area Work
The existing structure transitions from three lanes (12 m/40 ft width) to two lanes (8 m/28 ft width) through the work area. Ramp entrances and exits compound the problem of space available for maintenance of traffic and the contractor's work area. Use of positive barriers to protect the work zone will limit access for equipment and materials. When working on the median lane, the contractor may have traffic on each side of its work area.
LDOTD's resources for bridge reconstruction/rehabilitation are limited. The scope of this project has been narrowed to a critical portion of the structure, which should not be delayed further. Early construction cost estimates for the project were $6-7 million, but further traffic considerations have escalated this cost to an estimated $8 million.
2.4 Project Status
The District Design section has worked for the last year to incorporate elements of the 1980 project and deck overlays undertaken in the Shreveport District to produce preliminary plans. As the impact of the need to prevent area traffic gridlock became apparent, the original drawings have evolved into a traffic control plan with some deck repair details added. The concept of rehabilitation remains the same, but the methods to achieve a quality project must meet the demands and constraints imposed by today's public.
In July 2003, a constructability review of the project was held in Baton Rouge with a team of contractors and DOTD personnel. No major innovations or solutions were determined at the review, but many specific details or options were presented for consideration.
Local officials and the public have been made aware of the proposed project and its potential impacts. The District Administrator has spoken to several groups to keep the area advised of plan development. Similar meetings have been conducted with area law enforcement and other emergency personnel, which will be affected by the project.