On Amtrak's "High Line" between Rea Interlocking now and A in NYP, the territory is 562, cabs, no waysides. Also, there are "cab signal" wayside signals outside of 562 territory, noteably at Lane interlocking, which when the "cab signal" signal is displayed, trains are to follow the speed shown on their cab signal unit, which is 80mph there, even though that regular interlocking rules and 261 rules are in effect - its to use the 80 mph crossovers, without requiring a reduction to 45mph (Approach Medium in the cab)
One of the differences between SEPTA's and Amtraks 562 territories, is that Amtrak has many interlockings very close together, and even though the only wayside signals in 562 are those of Home signals and only show the condition and occupancy of the track in the interlocking limits ONLY, you can see the next interlocking, and the next interlockings home signal, adn get an idea as to the condition of that interlocking up ahead, and train occupancy further up the line, unlike SEPTA, where the interlockings are further apart, and distant signals are not in service.
Also, to take full advantage of 562 territory, the ancient 4 aspect cab signal units used have to go. To go from clear to an Approach Medium in the cabs (allowing 45mph, don't get it confused with an approach medium fixed signal, allowing 30mph) means either MAS or slowing down alot. In order to satisfy the Automatic Train Control system, which requires an application of the brakes when the cab signals drop (change to a more restrictive indication) a brake pipe reduction of at least 17psi (sometimes 25psi, depending on some equipement) is necessary to get the "suppression" light to come on, which is telling the ATC equipment that you are slowing the train adequately enough to comply with it.
At NJT before all the real old equipment was upgraded to SDU, (and ADU's capable of the 80 and 60 mph indiciations) speed display units - totally digital screens showing speed and cab signal indication by speed allowed, not by aspect, trains which would encounter a Cab Speed wayside signal aspect, or a cab signal change in their cabs, would have to respond to an Approach Medium in the cabs, requiring at least a 17psi brake reduction, and slowing the train from MAS speed, 60, 70, or 80mph or whatever, to get it under 45mph, and with a 17psi reduction, releasing the brakes before the train hits 45 or under (so you could slow down, and when the brakes are released, you would be going 45) is a no, no, and the system will dump the train. YOu have to hold that application until 45 is reached, THEN release the brakes, thats why trains slow down so hard, then speed up, because by the time the trains brakes have released, you may be going between 35 and 40. The SDU's allow the cab signals to come down gradually (at least in theory, its works.....okay) from MAS to either 80 or 60, then another cab signal change in the next cab signal block to 45, then to Approach (30), then to Restricting (20) for a stop signal up ahead. Not MAS to 45 to 30 to 20. The newer SDU system spreads out the distanced needed, and sort of prevents the rediculous slamming on the brakes necessary.
Last edited by Jtgshu on Sun Feb 05, 2006 3:37 pm, edited 1 time in total.
On the RR, "believe nothing you hear and only half of what you see"
John, aka "JTGSHU" passed away on August 26, 2013. We honor his memory and his devotion to railroading at railroad.net.