Before a single piece of heavy equipment rolls onto Doyle Drive, the entire replacement project, with demolition, excavation and construction, will already be played out virtually.
"Basically, what we call this is VDC -- virtual design and construction -- and what that means is we build it virtually before we build it actually," said Parsons Brinkerhoff engineer Brady Nadell who is part of the design team.
Nadell says the 3D modeling can help prevent delays and expense by anticipating problems. The virtual models also include the fourth dimension -- time.
"Hopefully, ideally, once you've found all the mistakes in the computer, you will experience less of them in the field and therefore you will have less unaccounted for costs," he said.
Caltrans animation of the completed $1.45 billion project shows how it should look three years, but getting there will require a variety of lane, road and ramp closures. Among the most painful, the ramps connecting Doyle Drive with the Presidio Parkway. The ramp from the parkway to Doyle Drive will be closed for 12 to 18 months. The ramp from Doyle Drive to the Presidio Parkway will be closed for the duration.
Caltrans hopes people who use those ramps routinely will find their own best alternate routes on surface streets. There will be an official detour through the Presidio.
Caltrans says it plans to inform the public of its plans in much the same way it has tried to let people know about detours and closures on the Bay Bridge. They will need to do that soon. Construction is supposed to begin in a few months.