LA JOLLA (CNS) - A groundbreaking ceremony and community celebration is scheduled Saturday to officially kick off construction of the $2.1 billion extension of the San Diego Trolley's Blue Line into La Jolla and University City.

The 11 a.m. event on the field at The Preuss School at UC San Diego will include a picnic, music and children's activities, as well as information about the 11-mile Mid-Coast Trolley extension and the construction schedule.

Preliminary work has been underway for most of this year, primarily involving the relocation of utility lines.

The San Diego Association of Governments, which is hosting the event, said the first 4,000 attendees will receive a commemorative T-shirt, a drawstring backpack or a miniature USB fan.

The Blue Line currently runs from San Ysidro to downtown San Diego. When the project is completed in about five years, trolleys will carry passengers north to the UCSD campus, and east to a terminus at the Westfield UTC shopping center.

The cost is being split between a $1 billion grant from the Federal Transit Administration and the county's TransNet half-cent sales tax.