OAKLAND -- Alameda County residents will vote in November whether to make their county the first in Northern California to take its transportation sales tax to a full cent, Alameda County supervisors decided Tuesday.

The vote was 5-0 to go to voters for the second time in two years with a tax increase to expand spending by $7.8 billion over three decades.

The money would be spent on freeways, roads, buses, BART, walking and biking trails and other measures to ease traffic congestion.

If it wins approval by two-thirds of voters, the measure would double the current half-cent tax to a full cent, and extend it from 2022 to 2045.

"We need this to keep the public moving, to fight congestion, to reduce air pollution, and put people to work," said county Supervisor Scott Haggerty, who also chairs the transportation agency that oversees the sales tax. "The timing is right. The economy is improving. Congestion is worsening, and people want ways to avoid being stuck idling in traffic."

The previous ballot measure narrowly lost by 721 votes in 2012, when the tax increase would have been forever -- a permanence that made many voters nervous.

This time around, the Alameda County Transportation Commission stripped out the "forever" clause and asked for the same money for the same projects with the tax needing voter approval to extend it past 2045.

"We listened to the public," Haggerty told reporters at a news conference after Tuesday's vote.

The measure would provide a local share of several planned transit and highways improvements to get them off the ground and attract other state, federal and regional funds, said backers of the tax.

BART would get $400 million of sales tax money for the BART extension to Livermore. While much more money would be needed, the local tax money would provide "seed" money giving leverage to secure other funds, said BART Director Tom Blalock.

Roughly half of the tax proceeds would be spent on public transit and paratransit, and a $2.3 billion share would go toward fixing county and city roads.

The nearly $8 billion in sales tax would yield a total of some $20 billion in economic activity in Alameda County, according to an analysis by the Bay Area Council Economic Institute.

The sales tax also will yield the equivalent of 150,000 yearlong jobs -- some them permanent jobs such as bus drivers and some temporary ones in construction, the study concluded.

"We need these funds to succeed economically and provide the job base for the future," said Jim Wunderman, president of the Bay Area Council, a business coalition.

The spending plan for the tax increase was approved by all 14 city councils in Alameda County, plus the county Board of Supervisors.

Contact Denis Cuff at 925-943-8267. Follow him at Twitter.com/deniscuff.

highlights of sales tax spending plan
$2.23 billion for city and county street maintenance
$1.45 billion for AC Transit operation and maintenance
$400 million for down payment on BART extension to Livermore
$651 million for bike and pedestrian improvements.
$190 million to test and carry out program of free transit pass for youths.
$90 million to modernize BART stations in Alameda County
$161 million for freight movement improvements
.