Buffalo’s “Cars Sharing Main Street” project is proceeding, with construction to bring two-way traffic to the 500 block, between Chippewa and Mohawk streets, scheduled to begin in the fall.

Mayor Byron W. Brown, standing with the Main Street construction and passing trains as his backdrop, announced Tuesday that the city awarded Mark Cerrone Inc. the $15.7 million contract to reconstruct the 500 block.

The entire 500 block project, including planning and design costs, will cost $21 million. A $15 million federal grant, which was won last year, and $10 million from the state will fund the redevelopment.

Cerrone was also the successful bidder for the ongoing 600 block construction, an $8 million project, that will bring traffic back to Buffalo’s Theater District between West Tupper and Chippewa streets.

As the 600 block construction concludes “sometime in the fall,” the 500 block construction will begin “simultaneously,” according to Brown. It will take 16 months from that point to be completed.

“It will transform Main Street into one of the most-complete streets in the entire State of New York,” he said.

The costs vary widely for each block of the project due to the different constraints of each, city sources said.

Public Works Commissioner Steven J. Stepniak explained how the trains, cars, bikes and pedestrians will share the strip once construction is complete.

The project includes installation of new curbs, sidewalks, street lights and traffic signals.

Brown said Main Street is “ripe for investment,” and the 600 and 500 blocks are seeing over $70 million in private sector spending.

He said Main Street’s no-traffic rail system, which was installed in the 1980s, “essentially killed retail in downtown Buffalo.” This city is optimistic that opening up Main Street for traffic and parking will revitalize the strip, he said.

It would cost $10 million for the project to continue to Lafayette Square and an additional $30 million to extend it to Church Street, Stepniak said. He said he feels the city will be successful in “working with our partners in state and federal government” to secure money.

The 500 and 600 block projects are a continuation of the $2.2 million 700 block project, which brought two-way traffic to that section of Main Street in 2009.