Alameda County Public Works became aware that there was an issue all along the roadway on February 22 and had kept an eye on it for six weeks, until Tuesday when the entire section gave way.
The area could be closed for months. "What we're doing right now is we're setting up a hard road closure, so Redwood Road between Oakland and Castro Valley will be closed to thru traffic at this section," Alameda County Public Works employee John Medlock said.
The issue -- a 50-foot section of roadway that collapsed earlier this week, one that began showing signs of failure six weeks ago.
The rains may be dwindling, but the ground just keeps moving. Redwood Road is popular with commuters, trying to cut through from Castro Valley to Oakland or Moraga.
It's also a favorite route for cyclists from both Contra Costa and Alameda Counties.
"There are a lot of roads like this that have cracks that look like they're about to tumble off," said cyclist Joel Fajans. "And occasionally they do. I climb tunnel road for instance and there are two sections that look like they're about to tumble off, but they haven't in a year, which doesn't mean they won't tomorrow."
The sinkhole is just the latest example of what Public Works crews all over the Bay Area have been dealing with this winter, one that saw record rains in many areas.
On Redwood Rd., it will be no-go for a while.
"On the weekend, motorcyclists and bicyclists, this is a popular route... so they're going to have to pick an alternative route, along with the commuters," Medlock said.