OAKLAND (KRON) — Caltrans crews are working to remove a major section of the old Bay Bridge Thursday morning.

Crews started working around 6 a.m. to remove the first 504-foot truss span, Caltrans officials said.

The removal should take two 14 hour days, according to Caltrans officials.

On the first day, crews will focus on severing the truss from its towers and its slow decent toward the bay below. Crews will then concentrate on setting the truss down on barges and transporting it to the Port of Oakland for disassembly on the second day.

The lowering operation dependent on the weather. Heavy rains or high winds could cause changes.

This is the second part in a three-part process to dismantle the old Bay Bridge.

Phase I was completed the end of 2015 when cantilever section and S-curve to Yerba Buena Island was demolished. Now, Phase II continues with removal of the first five 504s and then removal of fourteen 288-foot truss span sections that extend to the Oakland shore. Phase III will focus on the demolition of the remaining marine foundations.