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I took a tour of the tunnels with my High School science club while the system was under construction. It was fascinating and I learned a lot about why they mad

I took a tour of the tunnels with my High School science club while the system was under construction. It was fascinating and I learned a lot about why they made the decisions they did. Tunneling for Metro was staggeringly expensive and having a third track would have greatly increased costs. The rails of the Metro are 1/4" closer together than standard American gauge, to reduce the side-to-side motion of the trains, which have standard gauge trucks. This allowed them to make the tunnels just a little bit narrower and saved millions in tunneling costs. But, clearly, this does complicate maintenance.

pwg 11y ago
> Tunneling for Metro was staggeringly expensive This probably had greater play in the reasoning years ago to forgo an extra track than we realize at this time. Most of the DC Metro was built by tunnel boring underneath already existing DC buildings. Very little, until one gets out to the suburbs, was built by open-cut and backfill, and even less of the system is surface grade. The planners in the late 50's to mid 60's, budgeting out 2*X (where X is likely a largish two digit number) of miles of tunnel boring, likely thought they were making a great money saving decision by not boring a third or fourth tunnel. And since typical human nature is to not think of the "what can go wrong" scenarios before they actually go wrong, those same planners likely never considered the "how do we fix track in tunnel 2 without having to half shut the system down to do so?" aspects of their decisions at the time.
- potatolicious 11y ago
  > "And since typical human nature is to not think of the "what can go wrong" scenarios before they actually go wrong, those same planners likely never considered the "how do we fix track in tunnel 2 without having to half shut the system down to do so?" aspects of their decisions at the time." Having met transit planners before, I think you're probably not giving them enough credit. The sort of hellish clusterfuck that happens when things go wrong in a 2-track system is well understood and not new even during Metro's planning and construction. More likely it was decided that a 2-track system that went straight to hell the moment something went wrong is a better choice than nothing at all, which is the alternative. It's not that they were trying to save money, but rather trying to fit the system within a budget that simply couldn't get any larger. Same deal here in NYC - the new Second Avenue Subway is 2-track even though everyone, the MTA included, knows the problems inherent in it. The problem is that there is literally no way to cough up enough money to make it a 3- or 4-track subway. Public transit has been a dirty word in American politics for over half a century, and the willingness to invest isn't much different. These weren't short-sighted decisions, they were entirely cognizant of the shortcomings, but there wasn't any other choice.
- rootbear 11y ago
  The downtown was a mix of boring and cut and fill. We moved to DC in 1971, while much of downtown DC was torn up, with lots of detours and one-way streets. I remember whole blocks that were just steel plates over pits. My father was not much of a city guy to begin with, but when he found out that most of the maps were wrong, because of all the temporary changes to one-way streets and such, he just revolted. It offended his private pilot sensibilities for the maps to be so wrong. It was hard to get him to go into DC for a long time. One reason for some of the cost overruns was that Metro discovered that many of the buildings they were boring under weren't built very well and they had to do a lot of extra, unplanned, work to strengthen the foundations. I remember a building somewhere around Florida and U Street that had these massive girders holding it up while Metro rebuilt it's foundations. Who knows? Maybe that extra work helped us during the East Coast earthquake a few years back.

pwg 11y ago

> Tunneling for Metro was staggeringly expensive This probably had greater play in the reasoning years ago to forgo an extra track than we realize at this time. Most of the DC Metro was built by tunnel boring underneath already existing DC buildings. Very little, until one gets out to the suburbs, was built by open-cut and backfill, and even less of the system is surface grade. The planners in the late 50's to mid 60's, budgeting out 2*X (where X is likely a largish two digit number) of miles of tunnel boring, likely thought they were making a great money saving decision by not boring a third or fourth tunnel. And since typical human nature is to not think of the "what can go wrong" scenarios before they actually go wrong, those same planners likely never considered the "how do we fix track in tunnel 2 without having to half shut the system down to do so?" aspects of their decisions at the time.

potatolicious 11y ago
> "And since typical human nature is to not think of the "what can go wrong" scenarios before they actually go wrong, those same planners likely never considered the "how do we fix track in tunnel 2 without having to half shut the system down to do so?" aspects of their decisions at the time." Having met transit planners before, I think you're probably not giving them enough credit. The sort of hellish clusterfuck that happens when things go wrong in a 2-track system is well understood and not new even during Metro's planning and construction. More likely it was decided that a 2-track system that went straight to hell the moment something went wrong is a better choice than nothing at all, which is the alternative. It's not that they were trying to save money, but rather trying to fit the system within a budget that simply couldn't get any larger. Same deal here in NYC - the new Second Avenue Subway is 2-track even though everyone, the MTA included, knows the problems inherent in it. The problem is that there is literally no way to cough up enough money to make it a 3- or 4-track subway. Public transit has been a dirty word in American politics for over half a century, and the willingness to invest isn't much different. These weren't short-sighted decisions, they were entirely cognizant of the shortcomings, but there wasn't any other choice.
rootbear 11y ago
The downtown was a mix of boring and cut and fill. We moved to DC in 1971, while much of downtown DC was torn up, with lots of detours and one-way streets. I remember whole blocks that were just steel plates over pits. My father was not much of a city guy to begin with, but when he found out that most of the maps were wrong, because of all the temporary changes to one-way streets and such, he just revolted. It offended his private pilot sensibilities for the maps to be so wrong. It was hard to get him to go into DC for a long time. One reason for some of the cost overruns was that Metro discovered that many of the buildings they were boring under weren't built very well and they had to do a lot of extra, unplanned, work to strengthen the foundations. I remember a building somewhere around Florida and U Street that had these massive girders holding it up while Metro rebuilt it's foundations. Who knows? Maybe that extra work helped us during the East Coast earthquake a few years back.