The crunch of a bulldozer biting into a Crenshaw Boulevard school signaled the start of heavy construction Tuesday on the latest addition to Los Angeles' steadily expanding rail network, a light-rail line that will connect the Mid-City area to the South Bay by the end of the decade.

The 8.5-mile Crenshaw Line will be the first new rail service in a generation to traverse transit-dependent South Los Angeles, increasing connections to a train system that now reaches to Long Beach, the Westside, the San Fernando Valley and the San Gabriel Valley. The Crenshaw Boulevard corridor last had a rail link in 1955, as part of L.A.'s sprawling street car network.

"This is a day that Angelenos deserve, a great day for Los Angeles," Mayor Eric Garcetti, said. The $2.06-billion, eight-station route will bring development, employment and foot traffic to the area and make it easier to reach Santa Monica and downtown, officials said.

Tempering the upbeat mood of Tuesday's groundbreaking was concern over the effect of five years of construction on small businesses, as well as renewed complaints about who will get jobs on the project. The Los Angeles County Metropolitan Transportation Authority's demolition work and track-laying, as well tunneling from Exposition Boulevard to 48th Street, is expected to create years of lane closures.

"The Crenshaw Line has a kind of symbolic value, in that the city is making a big investment in the community," said Franklin Gilliam, the dean of the UCLA Luskin School of Public Affairs. "But it raises an interesting question: At what price, progress?"

Protesters gathered outside the groundbreaking ceremony said construction could force shops to close. Audrey Reems, who runs a Montessori preschool at 48th Street and Crenshaw Boulevard, said Tuesday that parents have told her they will move their children to another school if the construction dust is too heavy or noise is too overwhelming. "We don't want this to divide our community," Reems said.

Some South Los Angeles community groups also complained Metro is not hiring enough workers from the communities most affected by the disruptions. "We don't mind leaving our area for jobs," said construction worker Jap Willins, who held a banner with other members of the Young Black Contractors Assn. of South L.A. Inc. "But if work is here, we want a piece of it."

Metro can't hire by geography or ZIP Code because the project is receiving $700 million in federal grants and loans funded by taxpayers across the U.S., officials have said. Metro will reserve 40% of the project's work for economically disadvantaged workers. Contractor Walsh/Shea, a joint venture between Walsh Construction and J.F. Shea Construction, has promised to hire construction trainees and so-called disadvantaged workers — including veterans, the homeless and applicants with criminal records — partly by reaching out to building and trade unions.

One unresolved issue is linking the so-called Crenshaw/LAX line to Los Angeles International Airport. Despite its name, the route will stop 1.5 miles to the east of the terminals, at Century and Aviation boulevards. It will be the second rail line to stop short of the airport; the South Bay's Green Line is near LAX's south runways, but passengers must board shuttles to reach the terminal area.

Metro and Los Angeles World Airport officials are negotiating a LAX connection from the Crenshaw line that will probably include some kind of people-mover, similar to the train that circulates between terminals at the San Francisco International Airport. A decision on that project is expected later this year.

laura.nelson@latimes.com