The condition of the region's roads improved slightly with a recent infusion of federal stimulus dollars, but the streets still suffer from wear and tear and risk sliding into distress, a regional transportation commission reported Tuesday.

In a conclusion all too familiar to many motorists, the annual state of the pavement report tells drivers they are in for a bumpy ride dodging potholes in many areas that put them at risk of having to pay for front-end alignments.

Some cities with newer roads bucked the trend. Brentwood for the second straight year earned honors for best roads in the region.

Using a 100-point scale, the MTC concluded the three-year average grade for 42,000 miles of Bay Area city and county roads was 66. That's a "fair" grade overall, the MTC said, and up a single point from last year's three-year average grade.

MTC officials said they are pleased that conditions remained stable after an investment of $122 million in federal stimulus dollars in 2009. But they are worried that the average score remains too close to what the MTC classifies as "at risk," where pavement can decline rapidly and require costly rehabilitation. That occurs when road conditions slip below 60 points.

"Despite the federal stimulus dollars, the best the roads have been able to do is basically to tread water. We have to do better," said Scott Haggerty, an Alameda County supervisor who leads the powerful nine-county transportation commission.

California's gas tax of 18 cents per gallon, a main source for road maintenance funds, has not changed since 1994, and state lawmakers continue to be reluctant to change it.

Inflation has eroded the value of that tax to keep up with wear and tear on roads. In 1953, the state gas tax was 6 cents per gallon, which would have the current buying value of 48 cents per gallon when adjusted for inflation, said John Goodwin, a transportation commission spokesman.

"We really worry about roads with a score below 60 because that's where roads can deteriorate very rapidly and need heavy investments to rehabilitate," he said.

Most counties have enacted a sales tax for transportation to help with road repairs. Napa and Solano counties have not.

Cities with newer roads, flat terrain and heavy emphasis on preventive maintenance have roads in better shape, Goodwin said.

Brentwood's score of 85 was the best in the Bay Area, earning a "very good" grade, but still short of the 90 score needed to be "excellent." Dublin had the sixth best roads with a score of 80.

Orinda, where steep, old roads are costly to maintain, improved by one point to a score of 48, the worst in Contra Costa County, but not in the region.

Unincorporated roads in Sonoma County ranked worst in the region with a score of 44.

Reach Denis Cuff at 925-943-8267. Read the Capricious Commuter blog at www.ibabuzz.com/transportation.