Caltrans has begun major demolition work on another critical section of the Bay Bridge approach. The construction will close down a section of Second Street until Monday morning.

Caltrans will have to demolish and cart away 18,000 cubic tons of debris, enough to fill a football field to a depth of up to 10 feet. Piece by gigantic piece - Caltrans crews are demolishing the last of the old eastbound approach to the Bay Bridge.

Bart Ney, Caltrans: "Originally this project was planned to work over 20 weeks, but the community came together with us and they said they'd rather just get it all over with as soon as possible. So we have condensed that 20 weeks worth of work, into about two and a half to completely demolish all of this."

The center of activity in this phase is a three block long stretch of eastbound 80 at Second Street adjacent to the clock tower. Eastbound 80 traffic began moving in a new route on Wednesday.

Demolition crews are using what's called a scissor jack - sort of a mechanical looking dinosaur - it took about 8 minutes for it to chew through the steel beams that have held the approach in place for 70 years and supported millions of cars. The upper deck is being pecked to death - by a jackhammer - which sends a hail of rocks and rebar down below. Caltrans reports not one worker has been injured on this job.

It is quite a sight and quite a sound. The demolition is taking place right outside Kerryann Blasi's Second Street loft window. After a restless night - she decided to go ahead with her dinner party.

Kerryann Blaisi: "It was planned weeks ago before I knew this was going to happen. We thought about changing the location and everyone thought what the heck, when else are we going to see this happen again."

Sterling Street on-ramp is supposed to be open on and off during the course of this weekend - it looks like it will be closed most of that time. There will be some detours if you plan to come to San Francisco during the early hours of the Sunday morning. The whole new improved San Francisco side of the Bay Bridge approach will be completed by 2009, and the new Bay Bridge by 2013.