Photo: Santiago Mejia, The Chronicle Photo: Paul Chinn / The Chronicle 2017 Photo: Santiago Mejia / The Chronicle Photo: Noah Berger / Special To The Chronicle Photo: Paul Chinn / The Chronicle 2017 Photo: Natasha Dangond / The Chronicle 2017

The Bay Area has the worst roads in the nation, according to a new report by TRIP, a Washington, D.C.-based transportation research group, that seeks to bolster a campaign by California transit officials to preserve the state’s recent gas tax hike.

Seventy-one percent of the streets in San Francisco, Oakland and nearby cities are dilapidated, and the average motorist loses $1,049 a year in repair costs from driving on the bumpy pavement, the report said. The San Jose area has the second-worst roads, with 64 percent in poor condition.

Researchers at TRIP evaluated arteries and freeways in the nation’s most populous cities, separating them by size. The San Francisco-Oakland area had the highest share of poor roads in cities with a population of 500,000 or greater. Eastern Contra Costa County ranked worst among mid-size urban areas, with a population of 200,000 to 500,000. Fifty-seven percent of its roadways are badly deteriorated.

The results mirror those of an August report that TRIP produced specifically for California, which makes a direct pitch for keeping the gas tax increase, SB1.

“The elimination of SB1 revenues would reduce funds available in California for transportation projects to improve road, highway and bridge conditions, improve traffic safety, enhance pedestrian and bicycle facilities, improve public transit and relieve traffic congestion,” the group said in that report.

TRIP is a nonprofit research group representing road builders, engineers, insurers and other transportation interests.

California raised its gas tax by 12 cents a gallon last year and its diesel tax by 20 cents a gallon, a move designed to generate $5.2 billion annually to patch potholes, beef up mass transit and mend aging bridges. It's facing a repeal measure this November.

The chair of that measure’s campaign, Carl DeMaio, called the TRIP report “a PR stunt” and criticized the group as “an enterprise that’s all about raising taxes on working families and handing the money over to the government.” His campaign started a bus tour Wednesday, traveling up the state from San Diego to Sonoma.

Kwame Agyare, region director at the American Society of Civil Engineers and a leader in the effort to preserve the gas tax, said he experienced the road craters firsthand when his car hit a pothole that contributed to a $1,100 repair bill. He touted the report’s findings.

“As a civil engineer, I know what needs to be done to make our roads and bridges safer and our transit systems more efficient,” Agyare said, arguing that the gas tax repeal “threatens to set California back” by putting 6,500 critical transit and infrastructure projects at risk.

It appears that pavement conditions in the Bay Area stagnated over the last few years. TRIP’s 2016 national report on poor roads also named the San Francisco-Oakland region as the worst offender, with the same 71 percent share as this year. At that time the report’s authors estimated a slightly lower annual cost to Bay Area motorists, at $978.

Vehicle travel throughout the U.S. increased by 16 percent from 2000 to 2016, putting significant strain on roads and highways. Driving by large commercial trucks surged at double the rate for all vehicles, accelerating as the economy recovered from the great recession. Nationally, heavy truck travel is expected to grow by 56 percent from now to 2045.

Areas with rutted and potholed roads stand to lose business, as studies have shown that companies look at the quality of a regional transportation system when they decide where to open new headquarters or offices, the report said. The cost of fixing and maintaining streets and roadways also escalates once the pavement deteriorates beyond a certain point. A recent pothole study by the Bay Area Metropolitan Transportation Commission indicated that most of the region’s roads are hovering just above that threshold.

Yet the nation is facing a highway repair backlog of $419.5 billion, as shown by a 2015 status report from the U.S. Department of Transportation. It recommended boosting the nation’s annual $41 billion investment in road maintenance by about 50 percent, to $61 billion.

Roughest rides The 10 large urban areas with the worst roads, and the percentage of poor roads: 1. San Francisco-Oakland 71% 2. San Jose 64% 3. Los Angeles-Long Beach-Anaheim 57% 4. Milwaukee 54% 5. Honolulu 54% 6. Akron, Ohio 49% 7. Cleveland 49% 8. New York-Newark, N.J. 46% 9. Providence, R.I. 46% 10. Philadelphia 43% Learn more: To see the report, go to https://bit.ly/2R3rvI7 Source: TRIP

Most federal transportation funding comes from the 18 cents-per-gallon gas tax and 24 cents-per-gallon tax on diesel fuel. President Trump’s infrastructure plan would provide $200 billion in federal grants and loans, but state and local governments and the private sector would have to kick in $1.3 trillion to access the funds.

Congress “has not yet crafted a transportation program in response to the Trump proposal and would need to identify a long-term, sustainable source of funding to support increased funding for the federal Highway Trust Fund,” which helps supplement the gas and diesel tax money, the TRIP report said.

“The needs of our nation’s infrastructure continue to grow,” U.S. Chamber of Commerce Vice President of Transportation and Infrastructure Ed Mortimer said, reacting to the new TRIP data. He said it “provides clear evidence that deteriorating roads are a strain on motorists and bad for the economy. It is past time for federal lawmakers to come together to enact a long-term infrastructure modernization plan.”

Carolyn Bonifas Kelly, the associate director of research and communications at TRIP, said the report was not timed to coincide with the election, but that its authors “realize there are important conversations being had about the transportation system in California.”

Rachel Swan is a San Francisco Chronicle staff writer. Email: rswan@sfchronicle.com

Twitter: @rachelswan