Commuters from both sides of Lake Pontchartrain are going to be facing another change today as the Department of Transportation Development begins a two-phase plan to reroute traffic on Interstate 10 so that all cars will be traveling on the new Twin Span.

Workers began at dawn this morning, moving concrete barriers and directing eastbound traffic from the left side of the new eastbound Twin Span to the right two lanes of the bridge in phase one of the shift.

Currently eastbound traffic has to make a slight left turn at the top of the bridge entrance to get on the westbound part of the new span. Starting today, however, all eastbound traffic will not travel entirely on the eastbound side of the Twin Span to the Northshore.

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Then in two to three weeks, after work crews have re-striped the road and turned traffic signs around, phase two of the shift begins. Then, westbound traffic will share the Northshore ramp with eastbound traffic to get on the new westbound Twin Span. They will make a slight westward turn to get on the west span continue across the lake, make a slight east turn and come down on the Southshore, sharing that ramp with eastbound traffic. In other words, westbound traffic will no longer have to drive across the lake on the old, lower and storm damaged Twin Span.

DOTD spokesperson Sherry Dupre explained that to complete the new westbound Twin Span, workers have to build access ramps at each side of the bridge. To do that, they need to demolish the old Twin Span to give them room for the new access ramps. Work has already begun on the old eastbound bridge, and DOTD plans to tear down both bridges except for about 2,000 feet on the Northshore, which St. Tammany Parish will use for a fishing pier.

The new Twin Span was started in July 2006 to replace the old span, which was severely damaged by Hurricane Katrina.

For the past three years, part of the old westbound span was kept together with temporary trusses and a rubberized road surface.

The new Twin Span, is 21 feet higher than the old bridge, and has three lanes in each direction, including two wide shoulders that can act as extra lanes in case of hurricane evacuation. The project costs over $800 million in federal money. Dupre said that construction is right on schedule, and should be finished by mid-2011.

“We are very happy that we are this far along,” Dupre said.

Steve Heraty, assistant resident engineer with Volkert Construction Services that is overseeing the engineering of the bridge for the DOTD said that if the weather cooperates, the first phase of the shift should take about 6 to 8 hours.

Dupre said the shift won’t affect commuters going to the south, but will cause some headaches for people going to the Northshore, especially this afternoon.

“Expect intermittent lane closures,” Dupre said. “I suggest that drivers look for alternative routes.”

And remember, this is only phase one.