Inside Metra's busiest interlocking...

lstone19 wrote: First, from what I've seen, there are only three standard turnout speeds on the MD: 10, 25, and 40 although A-5 is an exception with the 15 for the curve including the junction switches at the east end. But is it really any different than having to remember all the oddball curve restrictions.

But I'll disagree about there not being many benefits to being able to change speed as you go through. For an outbound MD-W train, it's about 0.65 miles from the A-5 home signal to the A-5 exit signal. Traversing that distance takes 2:36 at 15mph and 3:54 at 10mph (and that's for a zero-length train; real times would be longer). It's 1/4 mile from the signal bridge to the junction turnouts / start of curve (it's so far east due to the 3-4 crossover that used to be there before 4 was pulled up), then 0.15 miles around the curve, and then another 1/4 mile for the west end of A-5 crossovers. By my calculations, the ability to keep the speed up right until the point of the restriction and accelerate as soon as clear saves me 1.5 minutes each way. For a daily commuter, that works out to about 12 hours per year.

But you forget that under Eastern style speed signaling 10mph turnouts don't exist, so the train would go 15mph anyway. Like I said what is occasionally lost in some flexibility is made up by not getting short changed in turnout speeds. Where did they even get 10mph from? #10 frogs are good for 15mph here in the east, are you folks using something different? For example one 10mph turnout at A-5 is ~190 feet from point to point. At North Philadelphia one turnout is ~170 feet and good for 15mph.

BTW using some distance measures I determined that additional medium speed turnouts could be installed in the plant even with the current bridge placements and that's not considering use of doubleslips.

Back to the question of WB on track 3 at A-5 and what signals do you get, I asked someone who should know and he said it's Diverging Clear (or Approach) no matter what the route. He seemed to think even if routed via the crossovers at the east end of A-5, you still get a Diverging signal although that disagrees with what Eric said about getting Restrictings when crossing over and staying on the C&M. But it sounds like WB C&M 3 to any Elgin track via the west end of A-5 crossovers gets you a Diverging signal.

Also mentioned was that as part of the current project, new signals, new switches (but not faster), and A-5 remoted to the Metra Control Center (which already controls B-12).

lstone19 wrote:Back to the question of WB on track 3 at A-5 and what signals do you get, I asked someone who should know and he said it's Diverging Clear (or Approach) no matter what the route. He seemed to think even if routed via the crossovers at the east end of A-5, you still get a Diverging signal although that disagrees with what Eric said about getting Restrictings when crossing over and staying on the C&M. But it sounds like WB C&M 3 to any Elgin track via the west end of A-5 crossovers gets you a Diverging signal.

Let me correct that... I've now been told by another source that C&M 3 to Elgin 3 gets a straight-route signal (e.g. Clear), not a diverging signal.