Bah, LZB's a better system.LZB requires additional wires to be installed between the rails which would be a no go here.
Works on the Canarse line, and it'd work a lot better if the NYCTA would get everything equipped on the line.That's debatable. From what I've heard the CBTC has been nothing but problems and the only saving grace is that they left the existing signaling system in place so there's immediate failover to the old, perfectly functional system. Even if they do get it working it is unclear if the whole enterprise will fail the cost benefit test. At least for the real railroads nobody seems to be proposing that track circuits be replaced for train detection.
In any case, the 10 or so trains a day the average main line in the US sees, a cab signal system isn't going to even have any effect on running times. There's CSS equipped lines with 10 times the traffic out there in the world that work just fine.The main lines that matter are the ones that see 50 trains a day, which is an ever increasing share of them. Besides the issue isn't CSS, its some newfangled wireless system. Basic 4 aspect CSS would have most likely prevented the Chatsworth crash. There is no need for PTC, no need for computers and wireless datagrams. The mandate should have been for the defacto national standard 4 aspect pulse code CSS. It's bullet proof and has a consistent track record dating back to the 1930's. Every one of the big 4 Class 1's use it somewhere on their system and all Amtrak locomotives are equipped.
BTW do people realize that once they start going wireless they are going to have to secure the system and I mean really secure the system in such a way it doesn't get blown out of the water at Defcon. Wireless means that any joker with a laptop and $30 bux worth of equipment can start sending false speed target to trains. The technology isn't hard, but to make a secure system railroads are going to have to deal with, bum bum bum, key management for the message authentication codes. They have to key every PTC unit in ever cab then re-key it probably monthly. Of course you know they'll never do this so at least if my Amtrak train is going slow, after 2015 I can just command it to go faster.
Port Authority Transit Corp.'s thoughts on the Lindenwold, N.J. High Speed Line were that a human operator is often more conservative than the Automatic Train Operation because the human might practice "defensive driving" to avoid being fired if the train doesn't stop in as short a distance as the computer thinks it should. Going down hill, a Lindenwold train coasts and increses its speed until it exceeds the signal system's speed limit, when the brakes automatically slow it down and then release. A human must run slightly slower to keep the train under the speed limit at all times, or possibly have to explain why not, at the risk of his job.On both PATCO and the DC Metro you are correct that the ATO runs the fastest possible time as constrained by the signaling system. However the comparison I am making is with a signalling system that is augmented by human judgement instead of hard and fast speed rules. Locomotive engineers use their own judgement on where to begin to brake based on route knowledge, signal indication, etc. So a freight train that passes an approach medium signal will begin to slow down sooner than an Amtrak train that can maintain 80mph right up to the interlocking then brake to 30mph in the last 2000 feet. All of the computerized systems have large safety margins built in so when you transition to them the system slows down. An experienced engineer is going to be able to operate his train with less margin for error than a computerized system will. Yes this sometimes results in mishaps, but I feel that is a worthwhile tradeoff given the amazingly few number of accidents that occur each year.
Washington Metro is another example. It's Automatic Train Operation just applies the brakes at a predetermined point (based on speed, location, and other factors) without worrying about overshooting the stopping point and hitting another train.
Are you suggesting that Postive Train Control computers will be programmed to run trains slower than past practice?
If you don't believe me look at at highway speed limits and advisory speed signs. Traffic engineers have all sorts of very sophisticated equations to determine what the target speed on any particular stretch of highway should be and we all know how much total BS they are. Flow of traffic on 55mph freeways is 70 and unless you're driving a 1960's Ford Galaxy you can take the cloverleaf ramp marked 25mph at 50mph. Imagine if the government required you to have a little box in your car that forced your car to actually obey all of those speeds. The railroads have already had the engineers show up and impose their conservative speed limits on everything, now they risk taking away the leeway the engineers had in following the track and signal speeds.