Last night we attended the special Westside Subway Extension meeting where metro discussed the impacts of tunneling under a residential area. Jody Litvak and David Meiger from Metro did an excellent job explaining the need to study 12 potential routings between Century City and Westwood, the testing metro has been doing in the area (seismic, water, and other hazards), how deep the subway would go (70-110 feet below the surface) and how Metro expected no observable surface impacts from tunneling or operations.
Jody presented a slide on damage to subway systems resulting from earthquakes: there hasn't really been any. Even in the 8.8 Chile earthquake this year, the subway reopened the next day with no tube damage. The surface fared less well. I guess the subway is the place to be during an earthquake.
(via The Source)
On the subject of earthquakes, the Santa Monica fault runs along Santa Monica boulevard, which complicates the Santa Monica-Westwood Boulevards routing. It also means that Metro will likely need to reinforce and widen the tunnels where they pass through the faults.
This meeting was the first time Metro presented the specific properties the different route options would tunnel under. Something I didn't know is that property rights extend to the core of the earth and that metro purchases easements for their tunnel right-of-way. The following two routes are, in my opinion, the most probably routings as they go between the Constellation station in the heart of Century City and the off-street UCLA Lot 36 option in Westwood. Both stations will have higher ridership and lower community impacts than the on-street Santa Monica and Wilshire Blvd options. The routing is subject to change as the engineering process progresses.
The Direct Option minimizes the distance the subway travels under homes:
Metro had been studying a Santa Monica to Westwood Boulevard option because it would appear that it would travel under fewer homes. They call this the "Westwood Loop" However, subways can't make hairpin turns, and this option still travels under a large number of properties:
Metro will release a presentation that counts how many homes each route will tunnel under (via The Source)
It would also be more expensive and result in a much longer travel time (via The Source)
When the public comment period came, I was expecting a slew of residents who were opposed to the project and didn't want the subway going under their house. The KTTV Fox 11 News reporter was also expecting some opposition:
There were 16 public comments. Fifteen were supportive of the subway and one commenter asked a question without expressing support or opposition to the subway. I think the lack of comments opposing the subway is a testament to the well-thought out presentation that addressed uncertainty with tunneling, earthquake hazards, and surface vibrations and noise from subway operation. If there was public concern and opposition amongst attendees before the meeting, the informative presentation quelled these fears.
In fact, one of the commenters is an architect who works worldwide on sound sensitive studios and facilities. He said that, in his opinion, with almost 100 feet of dirt between the subway tunnel and a building serving to absorb vibrations, that there would be no detectable impact from the tunnel operations. He also won the "from the neighborhood" award (commenters often disclose how long they've been living in the area) - he was baptized in the church where the meeting took place.