A jack-knifed big rig is blocking all eastbound lanes of the Dumbarton Bridge. There is no estimate when lanes will reopen.NEWARK, Calif. (KGO) -- A jack-knifed big rig has been cleared from eastbound lanes of the Dumbarton Bridge.There are residual delays past the bridge.Highway 237 or the San Mateo Bridge can be used as alternates.[Ads /]Check traffic maps and drive times here.Stay with ABC7 News for more on this developing story.[Ads /] Report a correction or typo