Comments on: Are London Heathrow’s ULTra Pods the Future of Transit? http://www.thetransportpolitic.com/2009/12/28/are-london-heathrows-ultra-pods-the-future-of-transit/ Fri, 10 Feb 2012 22:58:11 +0000 hourly 1 http://wordpress.org/?v=3.3.1 By: electric fence dog http://www.thetransportpolitic.com/2009/12/28/are-london-heathrows-ultra-pods-the-future-of-transit/#comment-96431 electric fence dog Wed, 27 Oct 2010 14:45:42 +0000 http://www.thetransportpolitic.com/?p=5020#comment-96431 Awesome read. I wish i could take advice like that and just do it. instead ailing give it some thought for per week then neglect it :( perhaps i can change Awesome read. I wish i could take advice like that and just do it. instead ailing give it some thought for per week then neglect it :( perhaps i can change

]]> By: Seb http://www.thetransportpolitic.com/2009/12/28/are-london-heathrows-ultra-pods-the-future-of-transit/#comment-63682 Seb Mon, 30 Aug 2010 18:22:00 +0000 http://www.thetransportpolitic.com/?p=5020#comment-63682 On the ULTRA website, it is written that the protection sytem is based on a fixed block system inside the guideway. Does anyone has information on that ? I can't understand that finally they don't use use only the distance to the leader inside the pod to provide safety. This is totally in contradiction with the PRT goals ... and it totally mimick the railway system. The only thing that remains is thus the on demand. I suppose taht they were unable too proce the safety of the pod independantly thus they had to rely on another system. They don't even use moving blocks thus the pod speed won't be taken into account in pod distance. Maybe this is the reason for the delay because the safety was not considered sufficient ? If the headway is increased too much, the detection system inside the pod has not enough range to detect the leader pod or is unable to see through the curve and grade. Thus you must have an alternate system to see further and keep a sufficient distance ahead. On the ULTRA website, it is written that the protection sytem is based on a fixed block system inside the guideway. Does anyone has information on that ? I can’t understand that finally they don’t use use only the distance to the leader inside the pod to provide safety. This is totally in contradiction with the PRT goals … and it totally mimick the railway system. The only thing that remains is thus the on demand. I suppose taht they were unable too proce the safety of the pod independantly thus they had to rely on another system.

They don’t even use moving blocks thus the pod speed won’t be taken into account in pod distance. Maybe this is the reason for the delay because the safety was not considered sufficient ? If the headway is increased too much, the detection system inside the pod has not enough range to detect the leader pod or is unable to see through the curve and grade. Thus you must have an alternate system to see further and keep a sufficient distance ahead.

]]> By: Seb http://www.thetransportpolitic.com/2009/12/28/are-london-heathrows-ultra-pods-the-future-of-transit/#comment-63661 Seb Mon, 30 Aug 2010 18:06:19 +0000 http://www.thetransportpolitic.com/?p=5020#comment-63661 How can you imagine that their is no redundancy in railroad !!! Aircraft level safety is no better than railway level safety please ... I work in railroads and excuse me but 10 million chance of accident in a single brake action is not acceptable at all. We usually work on a level of an accident on one billion on the system life (30 years). And remember that there are still accidents ! I also confirm that safety team usually takes large safety margin to take into account unknown effects. I doubt that a mechanical brake can activate in 50 ms. Remenber that a japanese team had to explore "explosive brake" to attain a specific performance ... Remember also that you cannot dimension your headway with the average time but you must use defensive values that are the worst possible. For example, this means that you must suppose that : - the leader pod brake has brick wall stop because it is stuck for example - the follower pod will break at minimum emergency brake power (or worst ...) - the reaction time is the maximum one thus counting all the different software cycle time that are used - that the ground is slippery in case it has rain or snwoed - etc ... Transportation is not a world of amateurs. You will transport babies and pregant women in quantities. Good will and hope is not enough. You have to be sure. Moreover, a single accident or incident can definitively stop all the system if a new danger is discovered too late. How can you imagine that their is no redundancy in railroad !!! Aircraft level safety is no better than railway level safety please …

I work in railroads and excuse me but 10 million chance of accident in a single brake action is not acceptable at all. We usually work on a level of an accident on one billion on the system life (30 years). And remember that there are still accidents !

I also confirm that safety team usually takes large safety margin to take into account unknown effects.

I doubt that a mechanical brake can activate in 50 ms. Remenber that a japanese team had to explore “explosive brake” to attain a specific performance …

Remember also that you cannot dimension your headway with the average time but you must use defensive values that are the worst possible. For example, this means that you must suppose that :
- the leader pod brake has brick wall stop because it is stuck for example
- the follower pod will break at minimum emergency brake power (or worst …)
- the reaction time is the maximum one thus counting all the different software cycle time that are used
- that the ground is slippery in case it has rain or snwoed
- etc …

Transportation is not a world of amateurs. You will transport babies and pregant women in quantities. Good will and hope is not enough. You have to be sure. Moreover, a single accident or incident can definitively stop all the system if a new danger is discovered too late.

]]> By: Nathanael http://www.thetransportpolitic.com/2009/12/28/are-london-heathrows-ultra-pods-the-future-of-transit/#comment-50835 Nathanael Thu, 01 Jul 2010 00:31:43 +0000 http://www.thetransportpolitic.com/?p=5020#comment-50835 Britain did reduce its construction of urban roads. But how about all of those "rural bypasses"? They're *still* building more of them! Britain did reduce its construction of urban roads.

But how about all of those “rural bypasses”? They’re *still* building more of them!

]]> By: Nathanael http://www.thetransportpolitic.com/2009/12/28/are-london-heathrows-ultra-pods-the-future-of-transit/#comment-50834 Nathanael Thu, 01 Jul 2010 00:24:48 +0000 http://www.thetransportpolitic.com/?p=5020#comment-50834 Any place in the country where it's impossible to get to work without a car -- *cars are effectively being subsidized* by the provision of transport facilities *only* for cars. You can't tell what the user preference would have been unless there *is* an alternative. Any place in the country where it’s impossible to get to work without a car — *cars are effectively being subsidized* by the provision of transport facilities *only* for cars.

You can’t tell what the user preference would have been unless there *is* an alternative.

]]> By: Nathanael http://www.thetransportpolitic.com/2009/12/28/are-london-heathrows-ultra-pods-the-future-of-transit/#comment-50832 Nathanael Thu, 01 Jul 2010 00:21:02 +0000 http://www.thetransportpolitic.com/?p=5020#comment-50832 There's some magical thinking here. The deadweight weight of the vehicle is not proportional to the number of people in it. Tiny 4-person pods are carrying an absurd amount of deadweight, though better than cars. Larger vehicles carry much less deadweight. While weight per axle is *one* issue in guideway construction -- and a major one, certainly -- another one is simply the number of vehicles crossing it. Run a "light" 4-person vehicles over your "footbridge"-weight bridge every 2 seconds and how often will you have to replace it? Every year? There’s some magical thinking here.

The deadweight weight of the vehicle is not proportional to the number of people in it.

Tiny 4-person pods are carrying an absurd amount of deadweight, though better than cars.

Larger vehicles carry much less deadweight.

While weight per axle is *one* issue in guideway construction — and a major one, certainly — another one is simply the number of vehicles crossing it. Run a “light” 4-person vehicles over your “footbridge”-weight bridge every 2 seconds and how often will you have to replace it? Every year?

]]> By: Nathanael http://www.thetransportpolitic.com/2009/12/28/are-london-heathrows-ultra-pods-the-future-of-transit/#comment-50830 Nathanael Thu, 01 Jul 2010 00:14:15 +0000 http://www.thetransportpolitic.com/?p=5020#comment-50830 PRT boards fewer people per vehicle. If there's a line at a stop, it will take a lot longer to load everyone than it will to load one large train, because everyone after the first four has to wait while the pod leaves and wait for the next pod to arrive, etc. It's stupid to compare low-capacity vehicles to high-capacity vehicles; they serve different purposes. If you seriously want PRT to replace autos on roads, compare it with autos on roads. PRT boards fewer people per vehicle. If there’s a line at a stop, it will take a lot longer to load everyone than it will to load one large train, because everyone after the first four has to wait while the pod leaves and wait for the next pod to arrive, etc.

It’s stupid to compare low-capacity vehicles to high-capacity vehicles; they serve different purposes. If you seriously want PRT to replace autos on roads, compare it with autos on roads.

]]> By: Nathanael http://www.thetransportpolitic.com/2009/12/28/are-london-heathrows-ultra-pods-the-future-of-transit/#comment-50828 Nathanael Thu, 01 Jul 2010 00:02:12 +0000 http://www.thetransportpolitic.com/?p=5020#comment-50828 For really short distances, a moving walkway or escalator is the best choice, frankly. Hong Kong has built some huge escalator systems. For really short distances, a moving walkway or escalator is the best choice, frankly. Hong Kong has built some huge escalator systems.

]]> By: Nathanael http://www.thetransportpolitic.com/2009/12/28/are-london-heathrows-ultra-pods-the-future-of-transit/#comment-50827 Nathanael Wed, 30 Jun 2010 23:59:57 +0000 http://www.thetransportpolitic.com/?p=5020#comment-50827 If you think of PRT as a substitute for *roads* rather than a substitute for *rail*, then sure, it does kind of make sense. Except then it's too expensive! It has to be fully grade-separated, and the reason roads get built is that they *don't* have to be fully grade separated. What would PRT be a good substitute for, then? Grade-separated roads? I guess so. It would be a decent replacement for expressways.... except that the PRT pods can't go onto the local roads from the expressways, so they lose that advantage, meaning that high-capacity rail makes more sense.... Now, design me a set of passenger cars which are 'roadrailers' and can merge onto an automated "PRT superhighway", and you have a *serious* idea. If you think of PRT as a substitute for *roads* rather than a substitute for *rail*, then sure, it does kind of make sense.

Except then it’s too expensive!

It has to be fully grade-separated, and the reason roads get built is that they *don’t* have to be fully grade separated.

What would PRT be a good substitute for, then? Grade-separated roads? I guess so. It would be a decent replacement for expressways…. except that the PRT pods can’t go onto the local roads from the expressways, so they lose that advantage, meaning that high-capacity rail makes more sense….

Now, design me a set of passenger cars which are ‘roadrailers’ and can merge onto an automated “PRT superhighway”, and you have a *serious* idea.

]]> By: James Anderson Merritt http://www.thetransportpolitic.com/2009/12/28/are-london-heathrows-ultra-pods-the-future-of-transit/#comment-50798 James Anderson Merritt Wed, 30 Jun 2010 20:17:52 +0000 http://www.thetransportpolitic.com/?p=5020#comment-50798 PRT "stops" (they're really too small to be called "stations") are offline. Through traffic proceeds on the mainline, while your out-of-towners are wrestling with the luggage and the kids. Merging into and out of mainline traffic is handled automatically, at the maximum safe possible speed to do so. On the mainline, traffic also proceeds at the maximum safe possible speed, so there isn't any "passing." Excess pods can be handled a number of ways. The most obvious is to automatically distribute "empties" around the system so that vehicles are always waiting for passengers, and not the other way around. But at times of light-traffic, an excess of empty vehicles (or any that were rejected by potential passengers because of being dirty or damaged) would collect at a maintenance barn. PRT “stops” (they’re really too small to be called “stations”) are offline. Through traffic proceeds on the mainline, while your out-of-towners are wrestling with the luggage and the kids. Merging into and out of mainline traffic is handled automatically, at the maximum safe possible speed to do so. On the mainline, traffic also proceeds at the maximum safe possible speed, so there isn’t any “passing.” Excess pods can be handled a number of ways. The most obvious is to automatically distribute “empties” around the system so that vehicles are always waiting for passengers, and not the other way around. But at times of light-traffic, an excess of empty vehicles (or any that were rejected by potential passengers because of being dirty or damaged) would collect at a maintenance barn.

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