The San Diego Association of Governments, the regional planning and transportation agency for the county and its 18 cities, reviewed a slew of legal documents and authorized the group’s executive team to move forward with the purchase of South Bay Expressway, the southern portion of State Route 125, at its Dec. 2 meeting.

A vote to continue contracting with South Bay Xpressway LLC, the entity now operating the only toll road in the county, for six months following the purchase passed 17-1, with Lemon Grove Mayor Mary Sessom opposed.

The road, which runs from State Route 54 to Otay Mesa and the U.S.-Mexico border, is owned by the state’s Department of Transportation but leased to SBX for 30 years.

The road opened in 2007 just as the recession was beginning, causing a big drop in ridership. SBX filed for bankruptcy protection in 2010.

Elected officials belonging to Sandag’s board of directors have indicated they are amenable to decreasing the current toll structure on the nine-mile roadway, but haven’t made a decision on this, said spokesman David Hicks.

The general plan is to lower tolls (it costs $4 one-way to travel the entire road) and boost its use, relieving congestion on Interstate 805.

The negotiated price for the road is $341.5 million. The bulk of the cost, some $268 million, will come from TransNet funds now allocated to improving I-805. The rest of the cost would come from debt financing, Hicks said.

Sandag’s board is expected to take a final vote on the purchase Dec. 16.

— Mike Allen