Client: Greater New Orleans Expressway Commission
Completion Date: On Hold
Scope of Services
Preliminary design report
Final plans, specifications and estimate of probable construction cost
Bidding
Construction Administration Services
The Lake Pontchartrain Causeway consists of two parallel bridges, each approximately 24 miles long that are connected at seven points by crossovers. Other than the crossovers, there are no shoulders or other areas for vehicles to safely pull out of the traffic flow in cases of emergency or breakdown. Even at the crossovers, there are no acceleration or deceleration lanes to provide safe access. Vehicles must slow to less than 15 miles per hour in traffic, in order to turn into a crossover. Then they must quickly pull out into moving traffic from a dead stop, without the benefit of acceleration and deceleration lanes.
The purpose of this project is to widen crossover number 4, located near the 12 mile hump, and provide acceleration and deceleration lanes for vehicles to safely access the crossover. In addition to the structural widening, future plans call for a detached commuter comfort station with public restrooms and potable water to be constructed adjacent to crossover number 4.
The planned widening will double the width of the Causeway and extend for almost a mile in length. AASHTO type III and type IV girders will be used for widening of the southbound and northbound bridge, respectively. 54" hollow cylindrical prestressed concrete piles will be used to support the bridge in one and two pile configurations.
Some unique challenges that our design team faced included:
- Sequencing construction such that traffic is not disrupted and remains safe at all times without the luxury of moving traffic away from the construction area.
- Widening the northbound and southbound bridges, which are nearly 50 years old, with modern construction materials and ensuring that the new and old structures perform integrally.
- Developing a set of plans that could be used for on site construction (in place) or off site construction (in a fabrication yard) of the new spans.
- Ensuring that salt corrosion is prevented through the use of high performance concrete and surface chemical treatments.
- Dealing with strict environmental issues and mitigation
