LIRR track capacities

[rr503]

Hi all,

I understand that the following question ignores the complexities of signal density, sidings, speeds, junctions etc., but I was wondering if there was some generally-accepted number for the throughput of a single track on the LIRR... Any elaboration on the effects those other factors have on said capacity would also be great, if known...

Thanks!

[Erie-Lackawanna]

If someone responds with a definitive answer, ignore them.

You can't ignore all those complexities; all of that goes into the determination of any track's capacity, as does the type of train traffic that uses the track(s) in question. There is no one answer unless you ask about a specific track between a specific pair of locations.

Jim

[rr503]

When discussing railroads with a high level of uniformity in traffic (so rapid transit and commuter ops) it is generally possible to discuss from a system design capacity standard. For example, on the NYC Subway, the vast majority of trackage is signaled to allow 30tph to run with a comfortable buffer. Of course, there are endless nuances to that number — curves, terminals, timers, dwell times etc change that capacity in a +/- 6tph margin — but it is nonetheless a number that can be held across most discussions.

I’ve had some conversations with folks who deal with the LIRR, and they seem to suggest that the LIRR has, in its various resignalling and re-interlocking projects, moved towards one of these more uniform standards of capacity — an impression that prompted my inquiry. If my impression is wrong, then let’s take Hicksville-QUEENS as our case study.