|
|
| Re: TA is obsessed with CBTC, and ''New'' tech for no reason. (580169) | |||
 |
|||
| Home > SubChat | |||
|
[ Read Responses | Post a New Response | Return to the Index ] |
|
||
|
Re: TA is obsessed with CBTC, and ''New'' tech for no reason. |
|
|
Posted by Jeff H. on Mon Mar 3 19:52:17 2008, in response to Re: TA is obsessed with CBTC, and ''New'' tech for no reason., posted by Stephen Bauman on Mon Mar 3 09:38:24 2008. First off, the average distance between signals on the system is350 feet (from one of the TA's presentation slides before the start of CBTC). Secondly, empirical inspections indicate that signals in and around stations are generally 300 feet apart or less. Don't know what is meant by "average" block length. It is based on speed and grade. Those shorter signal spacings around stations _require_ time control. You can't have the stop arm 300 feet back of the leader unless you can prove that the followed is approaching at less than a certain speed. The way station time is laid out the signals have a "long" block length (if that block is clear they are unconditionally clear) and a "short" length which is "enabled" when they are approached under time control. I'd assume those BOT design documents date from the 1920's. Reducing the variations to insignificance requires time standard and clocks throughout the system that are synchronized to that standard time. That technology wasn't available back then. It probably would have been possible using clocks driven by synchronous motors off a common main with another wire used to advance them all rapidly to a fixed resynchronization point periodically. But I'm not sure that's the point. Are you trying to slow down fast operators or get delayed trains back on schedule? |
|
|
|