French firm Vinci Construction Grands Projets has won a contract to construct a $366-million cable-stayed bridge that will span the Panama Canal on the historic waterway's Atlantic entrance.

The Panama Canal Authority (ACP) opted for the double-plane, twin-pylon design after examining bridges in Spain, Korea, France, China and Japan. The 4.6-km-long, 4-lane bridge, designed by the Berger Group and China Communication Construction Co., will have a 530-meter central span suspended 75 m above sea level by a pair of 207.5-m-tall concrete towers placed at either side of the waterway. When completed, the bridge will be able to handle 16,500 vehicles daily. There is room to expand the bridge to eight lanes to accommodate a maximum of 28,000 vehicles daily.

The French company’s $366-million bid bested offers by two international consortiums: Spain's Acciona Infraestructuras and Tradeco of Mexico ($430 million) and a joint venture of Brazil's Odebrecht and Korean’s Hyundai ($387 million). The bridge is slated for completion in late 2015.

ACP awarded the contract to Vinci on Oct. 30 following an in-house review of all the proposals. The three teams were pre-qualified to bit after ACP had examined them for technical criteria, experience and financial capacity to complete the project.

Clearance is a major concern. "The project alignment will pass over the [canal's] navigation channel and a railway, so its construction process should be developed as to not affect the safety of the maritime and rail traffic," says ACP project manager Mario Luis Montemayor de la Guardia.

Cruise liners that pass through the canal can be as high as 72 m. In comparison, the Golden Gate Bridge in San Francisco has a maximum clearance of 70.5 m above the waterline.

The ACP also chose a concrete superstructure due to the humidity of the tropical region, which would likely corrode a metal structure over time. The bridge was designed with a potential lifespan of 100 years—taking into account the possibility of a fourth set of locks being built, Molina explained.

Vital link

Currently, the only route across the waterway on the northern side of the isthmus is a two-lane road that passes directly in front of the Gatun Locks. As a result, the road must be closed every time a ship passes through. Only 1,000 vehicles a day cross the canal, but soon the connection will be severed due to the  $5.2-billion Third Lane Expansion, which consists of a third set of locks at either end of the canal. The new Atlantic locks, about a third of the way complete, will cut off the west side of the isthmus unless a permanent roadway is constructed.

At the time the canal expansion was approved, the Panamanian government passed a law that required a vehicular crossing to be started by the time the new locks were completed.  In 2010, the ACP examined a number of alternatives, including a tunnel underneath the canal. The final choice was dictated by the type of traffic expected to use the bridge, says Daniel Ulloa, head of the ACP's civil engineering section.

"We wanted to keep the slope at four or five degrees to handle the heavy equipment that are going to be using this crossing in the future," he says.

The bridge is slated for completion in the fall of 2015—a year and a half after the expected completion of the Third Lane Expansion project. A ferry will carry transiting vehicles across the waterway once it is needed.

The Vinci contract also includes an 8-km access road on the west side of the canal and a bridge over the Chagres River. The route circumvents the existing route over the Gatun Dam. That structure creates the Gatun Lake, which is the heart of the canal's navigation channel.  Vinci will also build smaller bridges for the roadways, including a span over the Chagres River outlet channel.

Canal officials have already begun feasibility studies examining the possibility of building a new bridge on the Pacific side of the canal. The rapid growth of Panama City, particularly development on the western side of the waterway, now taxes the capacity of 50-year-old Bridge of the Americas.