QUOTE: Originally posted by owlsroost Moving block is more about maximising line capacity, and so far it's proved tricky to apply it to mixed-traffic lines where there are big differences in speed and performance between trains and lots of junctions. Tony
QUOTE: Do you think Moving Block and In-Cab Signaling be better for these trains?
QUOTE: Originally posted by owlsroost The Inter-City 125 passenger trains used in the example have much better acceleration and braking than the older trains which the signal spacings (and braking distances) were designed for.
QUOTE: Originally posted by owlsroost There are actually now 6 aspects used in the UK - red, single-yellow, double-yellow, green, flashing single-yellow, flashing double-yellow. The flashing yellow aspects are used on the approach to medium speed junctions to give advance warning that the divergent route is set, so that the driver can brake appropriately. See http://www.railway-technical.com/sig-uktypes.html and http://www.davros.org/rail/signalling/articles/junctions.html for more info. Tony
QUOTE: Originally posted by CrazyDiamond Okay so let that be the 'bar' that is set for the yellow, or maybe a flashing yellow, and let a lower requirement be the yellow. Many signaling systems around the world bascially said "lets take our worse case scenario, and make that our advance notice (double yellow / flashing yellow), let our light weight and/or slow speed traffic get a single steady yellow, and be done with it. Most of ye in hear arugue that simplicity is a requirement for a RR to be cost effective, yet we turn around and argue that we need a signal system with dozens of aspects? I know 3 aspects is better than two, 4 better than 3, 5 better than 4, etc, in terms of theoritical efficiency and keeping trains fluid, but the higher costs assocated (with signaling systems with plenty of aspects (maintence costs, engineering costs, procedural costs, accident costs associated with human-signal 'confusion', etc)) I would argue would off-set most if not all the gains made. Yes? maybe no?
QUOTE: Originally posted by BaltACD Handling and stopping trains of such weight and lengh is a process that requires giving the engineer all possible advance notice of how he must operate his train at the next signal.
QUOTE: Originally posted by BaltACD Remember, way back when, traffic signals in the US only had 2 indications....Red=Stop and Green=Go....shortly there after is was determined that there needed to be a Yellow indication between the Green and Red indications in order to permit the intersecion to clear and minimize accidents.
QUOTE: Originally posted by chad thomas Short answer-Efficiency
QUOTE: Originally posted by chad thomas Short answer-Efficiency We could use two aspects, red-stop, and green-procede. Of course each train would have to move at a speed allowing it to be able to stop short of each signal. That would waste a lot of effort and time slowing and speeding up at signals. So we have multiple aspects that indicate to the crew what speed they need to be going well ahead of time so they can safely adjust there speed before that point yet maintain max speed untill the need to reduce / stop. Eventually signaling will get to the point where the "blocks" are moveing and reflect a safe brakeing distance between you and the train ahead, or any fixed speed restrictions (at least on high density lines).
QUOTE: Originally posted by CrazyDiamond In North American we have a large number of signaling aspects, yet the Brits only have 4. I know there are some unique differences between us and them, but come on.....if they can get by with only four, why do we need a few dozen?
QUOTE: The Brits have only 4 aspects and to many of their drivers can still not stop for a RED.
QUOTE: In North American we have a large number of signaling aspects, yet the Brits only have 4. I know there are some unique differences between us and them, but come on.....if they can get by with only four, why do we need a few dozen?
Larry Resident Microferroequinologist (at least at my house) Everyone goes home; Safety begins with you My Opinion. Standard Disclaimers Apply. No Expiration Date Come ride the rails with me! There's one thing about humility - the moment you think you've got it, you've lost it...
Never too old to have a happy childhood!
--David
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