The Elm City’s Downtown Crossing project, one of New Haven’s largest and most anticipated construction ventures in years, finally began this week.

The project will close exits 2 and 3 of the Route 34 expressway and replace the College Street Bridge in an effort to reconnect the downtown core with the Hill, a neighborhood in the city’s southwest. Yale’s medical, nursing and public health schools and hospital are all located in the Hill, which is currently separated from the rest of the University and downtown New Haven by part of Route 34. The Downtown Crossing project is expected to create traffic disruptions for at least two years, but city officials believe the project will be worth it in the long run for increased economic development, better connection within the city and more pedestrian walkways.

“For half a century, Route 34 divided the city and served as a reminder of the homes and businesses that were lost. No more — work is now beginning to remove the highway and restore the street grid,” Mayor John DeStefano Jr. said in a statement last week. “What was once a symbol of lost opportunity will again become a thriving part of our community.”

School of Architecture urban design professor Elihu Rubin ’99 said that when Route 34 was first constructed in the 1950s, the Oak Street neighborhood — considered a “slum” at the time — was torn down by city planners to make room for the new highway. While the highway, designed to bring suburban residents into downtown New Haven, was considered to be the lifeline of the city at the time of its construction, over the decades, the focus of city planners has shifted to remaking the continuous fabric of the city, he said.

Rubin added that the planning intervention of the 1950s, under the nationwide city planning philosophy known as Urban Renewal, is now considered a mistake, and the city views the Downtown Crossing project as an opportunity to make amends.

“The project is based on a very powerful idea,” he said. “It’s the idea that we can heal this cut, this wound, in the city.”

Ward 7 Alderman Doug Hausladen ’04 said that it has taken the city so long to start the project because it involves juggling ownership rights between the state of Connecticut, the city of New Haven and the project’s private developer.

“It’s one of the more complicated, probably the most complicated, project the city of New Haven has ever tackled,” Hausladen said. “It’s up there with the Big Dig of Boston, not in size and scope, but in complication.”

Karyn Gilvarg ARC ’75, executive director of the City Plan Department, explained that work on Downtown Crossing has just entered its mobilization phase, which involves preparing and moving materials into the site.

In the early stages of the project, Exit 3 of Route 34 will be closed and Massachusetts-based developer Winstanley Enterprises will build a 426,000 square foot office building. At the same time, the area currently occupied by Route 34 will be transformed into a pedestrian and bike-friendly environment, according to a statement last week by City Hall spokeswoman Anna Mariotti.

Officials hope that retail and housing will take root in the area. After the project is complete, 10 1/2 new acres of land will be available in New Haven for economic development, Murphy added.

In addition to connecting an isolated region of the city and providing more area for real estate and retail, planners hope the project will bring over a thousand jobs to New Haven. Downtown Crossing is expected to create 2,000 construction jobs during the project and 600 to 900 permanent jobs that will remain in the area after the project is complete, according to a statement released by Mariotti.

The office building at 100 College St. will be occupied primarily by biotechnology company Alexion Pharmaceuticals. With extensive ties to Yale, Alexion was founded in New Haven and is currently located in Cheshire, Conn. Alexion’s executive director of corporate communications, Irving Adler, said the company is excited to return to its roots in the Elm City.

“Our new facility will create employment across a wide range of specialties,” Adler said. “Jobs in anything you can do in the sciences, but most importantly, we are also an office. Marketing, finance, law, communications — every business function will be in there.”

All interviewed said the long-term benefits of Downtown Crossing will outweigh any short-term construction inconveniences. Democratic State Senate Majority Leader Martin Looney, whose district includes New Haven, said that all new development creates inconveniences but that the overall economic development will be worth any temporary problems.

Hausladen agreed, recounting his experience traveling from Science Hill to the medical campus while doing clinical research at Yale. Hausladen added that under the current highway arrangement, some of the world’s most brilliant medical minds are spending a quarter of their day riding the bus.

Currently, Gilvarg said, the physical division created by Route 34 makes it difficult for pedestrians to walk across different sections of New Haven. She added that the construction project will make it more convenient to travel back and forth between the Hill and downtown, making life in the neighborhood less isolating.

“The upper hill neighborhood is separated from downtown by this canyon,” Gilvarg said. “Psychologically and perceptually, there’s the feeling that New Haven is not a single, seamless city.”

The Downtown Crossing project is funded by the United States Department of Transportation’s TIGER II grant, the city of New Haven and the state of Connecticut.