CONCORD -- A proposed project to add on- and offramps at Highway 242 and Clayton Road is designed to reduce congestion on city streets and improve access to the freeway and downtown.
Contra Costa Transportation Authority staffers will answer questions about the project Tuesday during an open house from 6 p.m. to 8 p.m. at Concord Civic Center, 1950 Parkside Drive.
The project includes building a northbound on-ramp and a southbound off-ramp from Highway 242 at Clayton Road. Currently, there is an off-ramp at Clayton Road for traffic headed north toward Highway 4, but there isn't a corresponding on-ramp. Likewise, vehicles traveling south on Highway 242 must exit at Concord Avenue to reach downtown businesses and the BART station.
"The project purpose is to smooth the traffic, provide the missing interchanges and reduce congestion," said Susan Miller, director of projects for the transportation authority.
The agency also plans to build an auxiliary lane on southbound 242 connecting the Concord Avenue on-ramp with the new Clayton Road off-ramp. The new lane would give motorists time to merge into traffic on the freeway or exit at Clayton Road.
Built in 1962, the 3.4-mile Highway 242 connects Highway 4 and Interstate 680, providing a key route for people commuting to and from eastern Contra Costa County and jobs in central county, San Francisco, Oakland and Silicon Valley.
The intersection of Highway 242 and Concord Avenue is heavily congested, especially during the evening commute, said Ray Kuzbari, Concord's transportation manager.
Completing the interchange at Clayton Road will give motorists options and relieve some of the traffic on Concord Avenue by providing additional access points to Highway 242, he added.
The transportation authority is working on the environmental report for the project, which it plans to circulate for public comment in mid-2015. That process will help the agency determine which of two alternatives would be best -- building southbound on- and offramps at Franquette Avenue and the northbound on-ramp at Clayton Road; or putting in the southbound connection at Willow Pass Road.
Contra Costa Transportation Authority estimates the project will cost $30 million to $43 million, according to Miller. So far, $4.6 million from the countywide half-cent sales tax that pays for transportation projects has been committed to the project. Miller said the agency also will pursue state and federal funding.
Lisa P. White covers Concord and Pleasant Hill. Contact her at 925-943-8011. Follow her at Twitter.com/lisa_p_white.