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Comment by renewiltord | Hacker News Reader

Interestingly, the existence of TBMs has made SF Bay Area transit impossible to construct. Because TBMs exist, cut-and-cover is impossible since it can be pointed to as an alternative mechanism. However, they are hopelessly expensive here and consequently nothing gets built. Fascinating outcome.

I think that's a cool outcome in a coordination problem, where added technology makes neither technology workable.

This article was wicked sick, by the way. Great use of illustrations etc. This is free? Incredible. It's like the old web.

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The tunnel itself (regardless of method) isn't the expensive part. Dense urban environments have a ton of stuff underground that was never accurately mapped. People don't like a city block bursting into flames because you hit a 4" gas line or the building they are in collapsing because it has an unmarked piling.

Building up is actually a cheaper solution, we just need to get the NIMBYs under control. Imagine how nice it would be with 101 and 280 being double deckers the whole way.

Let's not forget 1989 Loma Prieta quake that caused the top deck of the bay bridge to collapse. https://en.wikipedia.org/wiki/1989_Loma_Prieta_earthquake

Which was actually a lot less dramatic than how people seem to remember it. A 70 foot section disconnected at one end. https://en.m.wikipedia.org/wiki/File:Bay_Bridge_collapse.jpg

Freeway construction has changed a lot since the 70s and 80s. We now use ductile concrete that can flex without breaking, do extensive soil analysis for footings, and add seismic isolation systems in high risk areas.

Perhaps, but the Nimitz Freeway probably makes a better example for what the commenter you were responding to was getting at:

"The highest number of deaths, 42, occurred in Oakland because of the collapse of the Cypress Street Viaduct on the Nimitz Freeway (Interstate 880), where the upper level of a double-deck portion of the freeway collapsed, crushing the cars on the lower level, and causing crashes on the upper level." (https://web.archive.org/web/20090707140922im_/http://home.pa...)

It will be down to policy not actual lack of data on infrastructure. Or is the expensive part the mapping? Or maybe the insurance?

Older bigger cities have built huge underground infrastructure recently. Londons power tunnels & crossrail for example.

It will be down to policy not actual lack of data on infrastructure.

It's absolutely about the lack of data about historical infrastructure. LA's Regional Connector line was delayed for years, and the budget ballooned by over a billion dollars, due to the discovery of thousands of undocumented utility lines (still in use) along the route. This necessitated dramatic changes to the project timeline and scope, since the construction authority had to reroute all of those utility lines.

Even better than expanding 101 and 280 would be to vastly improve the public transit down the peninsula. There is no reason going from my apartment in SF to San Mateo should take over 90 minutes via public transit. There should be constant rapid busses through SF to every Caltrain stop in the city. Hopefully Caltrains electrification + timing improvements make this all more feasible.

The fact that it’s one of the most technical areas in the world and we’re stuck driving between SF and the valley is a disgrace

For that matter, why Caltrain? it should all be Bart.

The name should not matter. There are sometimes good reasons to have more than one operator in a metro area for various reasons. However there needs to be one fare/transfer system across the entire metro with a price cap.

You can have various systems of zones or service levels, but there needs to be a maximum cost it is not possible to exceed to make it easy to budget. People who expect to hit that maximum will not hesitate to use transit or send their kids on it and thus are more likely to decide they don't need the car (even though a car probably costs more most people don't account for the costs of a trip)

They are piloting fares carrying over between transit rides, which could be a great solution for the people who think it’s too expensive. In general, taking public transit is already cheaper than driving, but it would be really really good if we could market that better. Some people think east bay -> SF for 5.50 each way is too expensive, when the bridge toll alone is almost the same price.

Bart would be great, but Caltrain is already there, and is electrified now. I definitely support bringing it all under one roof, but for now I just think it’s important to actually get Caltrain on a functional schedule.

In the future, I’d love if Bart could build an extension past millbrae, but they have some other more important things to do imo

The fact is that San Mateo was built as a suburb of San Francisco, and the transit choices were built as a function of residents commuting into San Francisco.

Why did you choose to live in San Francisco? You cannot expect the transit system to revolve on a dime around your housing & employment choices.

This is such a weird comment. If transit systems arent built around people's housing and employment, its useless. San Francisco is a huge city, with a significant population that commutes south as well. Even if the transit was originally made for people commuting into SF, it clearly isnt what is needed the most now. Downtown SF office space has significant vacancies, and I would guess there is a similar number of workers commuting south as there are commuting north.

Caltrain's current ridership (very poor) demonstrates the need to change the connecting systems so it is popular again. The idea of having rapid busses connecting to the caltrain stops (especially 22nd and bayshore stations) is hardly a massive thing, and could significantly improve transit across the Bay.

Building robust transit between SF and San Mateo is good for everyone, its not selfishness.

Why is it Caltrain’s fault that you chose to live far from a station, your employer chose to lease offices far from a station, and you chose to work for said employer?

I didnt say its Caltrains fault anywhere, I simply gave suggestions on how they can make public transit down the Bay significantly better, which should be their overall goal. Its also very relevant since their ridership is only <40% of pre-pandemic levels. I dont really understand why you are so against improving public transit access in a corridor that could really benefit. The whole area is a relatively plot of land, it is almost perfect for public transit

> San Francisco is a huge city

It's got under a million people, and is only the second largest in the Bay Area. It's locally very important, but let's not get carried away here.

Places in Italy where there is a lot worse stuff underground - like priceless archeological artifacts many to tunnel a lot cheaper than the US where there isn't such things (in the US there wasn't many materials available that would last in the natives trash piles - if there was there would be interest)

Fortunately, younger cities like London and Paris don't have the problem that ancient metropolises like San Francisco have, so they can build subway at a fraction of the cost of $4b/mi that SF needs to ensure that it's built right. There's a lot of history in California. Pretty unique in that regard.

To be honest, I like 280 without there being something on top of it, but if that's what's necessary to get a rail line down there I'd gladly accept it. Just the per-mile cost. Well, I'm not looking forward to paying more than half of every marginal dollar to the government so it can give it to its cronies who just happen to be husbands of famous California politicians.

I’m not sure they were at all implying that California was exceptional in that regard, to be fair, but at least that urban tunneling involves many costs besides the physical boring.

In any case, I wouldn’t use the UK as an example of tunneling efficiently. Crossrail, for instance, is on the order of more expensive urban US projects and there’s a fairly consistent recent history of either not building or letting existing rail infrastructure decay.

This link provides a decently contextualized comparison IMO, although it is slightly out of date now: https://pedestrianobservations.com/2011/05/16/us-rail-constr...

The funny thing is that Crossrail, the most humongously expensive UK rail project, is somehow a third the cost per mile as what SF quotes for its newest subway.

Here I was thinking you were talking about elevated rail and putting trains back on the lower deck of the bay bridge... but no, you're talking about freeway expansion in the core Bay Area? Not gonna happen.

> Not gonna happen.

I've never heard anyone successfully articulate why building enough roads to meet demand is such a bad idea. People need to get around and Caltrans has demonstrated they are far more competent and capable than BART or MUNI.

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