SAN FRANCISCO -- A dangling power cable outside the Treasure Island tunnel heading into the notorious S-curve section of the San Francisco Oakland Bay Bridge forced the shutdown of one lane on the lower deck during the Wednesday morning commute, authorities said.

California Highway Patrol Sgt. Trent Cross said a motorist reported the cable at around 6 a.m. The CHP, which has a beefed up present on the bridge attempting to slow motorists through the S-curve, quickly shut down the lane.

“It was important that we isolate the threat,” Cross said.

The dangling cable -- which provides power to the tunnel lights -- is just the latest of the dramas involving the vital commuter link since the new S curve was installed over Labor Day weekend.

Since that time, a 5,000-pound metal bracket has collapsed on the bridge, forcing the closure the span for six days for emergency repairs, and a semi-trailer truck has hurled off the bridge, falling 200 feet before exploding into a fatal fireball.

Cross said the CHP’s crackdown on speeders through the S curve section was still going on Thursday.

The speed limit on most of the bridge is 50 mph, but the limit drops to 40 mph on the S-curve, with a maximum of 35 mph recommended on the sharpest curves.

Over the weekend, the CHP issued nearly 200 citations, mostly for speeding, on S-curve section.

CHP Officer Herman Quon said between 11:30 p.m. Friday and 4 a.m. Monday, 169 drivers were cited for speeding, and nearly 30 for other violations, on the S-curve. Officers also verbally warned numerous motorists as part of an effort to educate the public on the dangers of speeding on the bridge.

The CHP began regularly saturating the bridge with officers during off-peak hours Thursday night and will continue indefinitely, Quon said.

There have been at least 43 accidents on the S-curve since that temporary section of the roadway was installed over the Labor Day weekend, including a fatal crash Nov. 9 in which a big-rig toppled over the side of the bridge.

"We looked at the 43 collisions we've had and they all pointed to one common denominator," Quon said referring to speed.

Quon said officers are able to use lanes closed by the California Department of Transportation to safely pull over motorists.

He said the enforcement is part of a larger effort to educate the public on the dangers of speeding on the bridge.

Caltrans has also installed additional safety measures near the S-curve, including extra speed limit signs, reflective striping along the barriers on the roadway's edge and raised bumps between lanes.