"old and tired and needs to be replaced"

For 42 years, the Gerald Desmond Bridge has straddled the waters of Long Beach's Back Channel, the primary link between Terminal Island cargo facilities and the city and freeways.

But the decades have taken their toll. The ships that now frequent the nation's second-busiest seaport are so big that many cannot fit under the bridge. Port officials estimate that the bridge carries 15% of the nation's cargo that moves by sea and truck, yet the traffic lanes are often jammed and any accident sends vehicles into adjacent neighborhoods.

And then there's the chunks of concrete that fall from the bridge, necessitating the nylon mesh installed to catch the debris.

On Monday, after years of planning, the Port of Long Beach began a nearly $1-billion project to replace the Gerald Desmond Bridge.

The bridge will remain in operation until the new one is completed, which officials estimate will be in 2017.

At 155 feet high, the Gerald Desmond is one of the lowest bridges in commercial seaports, leaving a small margin of error for captains navigating large vessels beneath the bridge, said Richard D. Steinke, executive director of the Port of Long Beach. For that reason, vessels attempt passage only at low tide.

The new bridge will be 50 to 60 feet higher to accommodate the larger container ships that currently cannot pass into the port, Steinke said. It will also be wider to accommodate the thousands of vehicles that drive across the bridge each day.

"This bridge has been the workhorse of the goods movement system," Steinke said.

When it was built in 1968, the Gerald Desmond Bridge was intended to handle relatively light traffic. But by the 1990s the Port of Long Beach emerged as the busiest container port in the nation; the Port of Los Angeles overtook it in 2001.

"No one could have imagined the amount of international cargo that has come into these two ports," Steinke said. The bridge is "old and tired and needs to be replaced."