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Mar. 22nd, 2008 06:32 am![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
khiemtranRETURNING single-deck trains to the metropolitan rail network would be a huge blunder, says the engineer who introduced double-deck carriages to Sydney.
Sydney's double-decker trains are actually quite a good case study of the perils of optimising to a set of too limited parameters.
The background: In the sixties, when the rolling stock was being modernized, double-decker trains seemed a really good idea. There was more capacity per carriage, less crowding, more people could get a window seat, etc. In order to fit with existing platforms and tunnels, each carriage was only double-decker in the middle. There was a single deck at normal height at each end and then passengers would climb either up or down half a deck to sit down.
This worked really well for a while, and then steadily less well as the years went by and the system grew. By then it turned out that there were other parameters that become more important in handling capacity. More people per carriage meant more could be carried without increasing the number of trains. This avoided the problem of scheduling extra services on increasingly congested shared tracks. Or rather it delayed the problem and let it grow larger and larger over the next forty years until at last a single minor incident could bring about massive delays across the network. It turned out that, as most of the rest of the world had discovered, being able to run more trains more often was better than being able to put more people per train.
The next thing that gradually became clear was that how people got on and off the train was more important than what they did once they were on it. No-one stuck on a stopped or late train (or worse, waiting forlornly on a platform) ever stopped to appreciate how nice it was to have wide bench seats and window views. The double deck configuration meant the carriages could only have one door at each end and the stairs and narrow aisles made it slower to get people on and off a crowded train. A jammed door is a catastrophe. A single deck metro train can have as many doors as you like and make them as large as you like.
The other problem was that by opting for a custom solution, they made it much more expensive to buy new rolling stock when the time came to modernize them again. Instead of being able to buy off the shelf, each new generation had to be engineered from scratch.
Sydney's double-decker trains are actually quite a good case study of the perils of optimising to a set of too limited parameters.
The background: In the sixties, when the rolling stock was being modernized, double-decker trains seemed a really good idea. There was more capacity per carriage, less crowding, more people could get a window seat, etc. In order to fit with existing platforms and tunnels, each carriage was only double-decker in the middle. There was a single deck at normal height at each end and then passengers would climb either up or down half a deck to sit down.
This worked really well for a while, and then steadily less well as the years went by and the system grew. By then it turned out that there were other parameters that become more important in handling capacity. More people per carriage meant more could be carried without increasing the number of trains. This avoided the problem of scheduling extra services on increasingly congested shared tracks. Or rather it delayed the problem and let it grow larger and larger over the next forty years until at last a single minor incident could bring about massive delays across the network. It turned out that, as most of the rest of the world had discovered, being able to run more trains more often was better than being able to put more people per train.
The next thing that gradually became clear was that how people got on and off the train was more important than what they did once they were on it. No-one stuck on a stopped or late train (or worse, waiting forlornly on a platform) ever stopped to appreciate how nice it was to have wide bench seats and window views. The double deck configuration meant the carriages could only have one door at each end and the stairs and narrow aisles made it slower to get people on and off a crowded train. A jammed door is a catastrophe. A single deck metro train can have as many doors as you like and make them as large as you like.
The other problem was that by opting for a custom solution, they made it much more expensive to buy new rolling stock when the time came to modernize them again. Instead of being able to buy off the shelf, each new generation had to be engineered from scratch.
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Date: 2008-03-22 12:20 am (UTC)If they'd doubled the frequency, things would have smoothed out more, and the train wouldn't have been so much hit and miss.
Funny how few rail companies realise that maintenance is part of running trains...
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Date: 2008-03-22 05:20 am (UTC)no subject
Date: 2008-03-22 11:39 am (UTC)The other thing I liked about Japan was the ticketing system. Get it wrong? There's a machine where you can pay up. None of this fear about being caught and fined; and if you're not certain what the price is, pay the minimum, and pay up at the end where it tells you. It's not surprising so many people take public transport if it's fast and reliable and cheap.