Crews worked to replace safety barriers on Vasco Road between Livermore and Brentwood, which caused delays Wednesday morning.
Traffic was reduced to one lane in the area where they were working.
Officials said the work began after 9 a.m., so it didn't interfere too much with the commute.
The barriers are safety enhancements for this dangerous road and the hope is that the barriers will help keep drivers from veering out of their lane.
Head on collisions are a problem on this road, which doesn't have a concrete barrier.
Crews told ABC7 News they think the work will wrap up Wednesday, but officials scheduled repairs for Thursday as well in case they need that much time.
A public works spokesman said this is routine work that they do once or twice a year.
Vasco Road safety barrier repairs in effect to prevent collisions