How would the Westside Subway Extension tunnel under homes?

Let’s face it: if someone showed up at your home’s front door one day and suggested they were considering building a subway under your lovely domicile, you might have a few questions.

That is precisely the reason that tonight’s community meeting for the Westside Subway Extension is being held. Project officials want to explain how Metro would go about tunneling under homes, if that is necessary — and it almost certainly will. The meeting is at 6 p.m. at the Westwood United Methodist Church, 10497 Wilshire Blvd.

The focus of the meeting is on the segment of the line that would run from Century City to Westwood. In the draft environmental impact report currently being prepared for the project, Metro is looking at three alignments (shown above), all of which would require the tunnels to go under residential properties. Here’s a Google map satellite view of the area.

Click above to see a larger image.

There’s a laundry list of points that officials will make as part of their presentation. Here are a few of the big ones:

•The subway tunnels for the existing Red and Purple lines run under multiple residential properties and there are also portions of tunnels under homes on the Gold Line. So far, Metro has not received any complaints of noise or vibrations from those tunnels. One reason for that is the tunnels here are fairly deep, with the tracks often 50- to 100-feet under the surface — and the tunnels are typically deepest between stations.

•As for the three alignments above, all of which are still being refined, the most direct connection would likely provide the quickest travel time between Century City and Westwood and is projected to be the least expensive to build (see the slide to the right). When staff makes a recommendation later this year on which route should be built, expense and train speed are — not surprisingly — major criteria.

•As for the number of residences the subway would go under, see the slide above. Metro does pay for easements to go under homes. How much, you ask? That’s still to be determined. It is fair to say that the amounts likely won’t buy that mansion in Malibu you’ve been eyeing.

•The latest generation of tunnel boring machines are designed to maintain pressure in the surrounding earth and greatly reduce the risk of settlement.

•Another issue that will impact the decision made by Metro officials is seismic activity in the area. In this case, the subway tunnel will need to cross a fault that generally runs along Santa Monica Boulevard. The answer to your next question is ‘yes’ — building the alignment that runs along Santa Monica Boulevard to Westwood Boulevard would be trickier because of the existence of that fault.

•The fault is also one reason that project officials are looking at two station locations in Century City. One is on Santa Monica Boulevard, the other on Constellation Boulevard. Projections show the Constellation station would like attract more riders — it’s closer to the heart of Century City — and public support has thus far tilted more toward Constellation.

•Can subways operate safely in earthquake country? The Red and Purple lines both have, of course, and the fascinating slide at right shows how subways have fared during some very large earthquakes over the past quarter century.

At this point, project officials are aiming to finish the draft environmental impact report this summer and make a recommendation on the route in the fall. It will then be up to the Board of Directors of Metro to approve a route and authorize the launch of the required final environmental document for the subway project.

A full copy of the presentation from the meeting will be posted on the project’s website this week.  You can also follow the subway project on Facebook.

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