The perennial traffic congestion on East Gun Hill Road will get far worse in the coming months, with the reconstruction of the bridge spanning the Williams Bridge Metro-North stop and the Bronx River Parkway.

Beginning in April, Gun Hill Road will narrow from four lanes to two on the bridge, which spans from Webster Avenue to Bronx Boulevard. The southbound Gun Hill exit from the Bronx River Parkway, which empties onto the bridge, will be closed for the nearly three years of work.

The Department of Transportation (DOT) has deemed the bridge unusable due to age and weathering, and it will be completely reconstructed. DOT estimates the project will conclude by December 2007.

Concrete barriers were erected on the roadway’s edges last week. Workers will soon enlarge Gun Hill by removing a portion of the sidewalk. Starting in April, the center part of the bridge will be demolished, traffic will narrow to two lanes, and the southbound Bronx River exit will close.

DOT has not yet said how they will mitigate traffic congestion during the roadwork. “They’re still working that out,” said Craig Chin, a DOT spokesperson.

Chin said specific information on traffic mitigation will be available in April. A traffic light hung last week at the 233rd Street exit from the Bronx River Parkway, the exit before Gun Hill Road, will presumably help ease extra traffic there.

A construction field office has been established at 3478 Webster Ave., just south of Gun Hill Road. The staff includes a community liaison, Thomas McCarley, who will answer public inquiries.

The East Gun Hill renovations are part of a larger DOT initiative to rebuild city bridges, many of which have been neglected. Most city land and waterway bridges are over 50 and 75 years old, respectively. The Gun Hill overpass was built almost a century ago.

But the need for the reconstruction will do little to offset the frustrations of thousands of drivers who pass through the intersection and exit ramp daily. Many employees at Montefiore Medical Center and North Central Bronx Hospital commute from Westchester and other counties in upstate New York.

“I don’t think it’s fair,” said Crysta Jones, a Montefiore employee who commutes 40 minutes each way from Westchester. “I understand they have to make repairs, but it’s going to create a situation that no one wants to be in.”

Since the filtration plant construction began, many Montefiore employees park in a lot on Webster Avenue instead of at Shandler Recreation Area in Van Cortlandt Park. Employees take a shuttle bus from Webster, and Jones worries that the trip, already 20 minutes during rush hour, will become unbearable.

Many buses also run along Gun Hill, including the busy Bx Nos. 28 and 30 to Co-Op City. “That is a nasty intersection no matter how you look at it,” said Janet Norquist, a Norwood resident who teachers in a Co-Op City middle school.

Andrew Laiosa, a Community Board 7 (CB7) member who works on traffic issues, was also concerned. “There’s already a major bottleneck there,” he said. Laiosa was especially outraged that the DOT has shown little concern about the impact on all the institutions concentrated in the area. “It’s just mindboggling,” he said.

DOT has done little to publicize the changes. Laiosa said he was invited by DOT to a meeting to discuss the proposal about a month ago, but it was canceled. He was not informed about the subsequent date, but said that Rita Kessler, CB7’s district manager, attended the session.

Kessler did not return calls for comment.

Chin said that a fact sheet about the project was distributed to community boards and the public. He said that DOT also met face-to-face with the boards. There was no mention of the project at last week’s Board meeting.