Regional Rail for New York: Frequencies

Screenshot 2016-05-20 at 1.45.55 PM
A frequency map for Scenario B. Thicker lines mean more trains in a given hour. The system’s service profile is determined by an hourly clockface scehdule: this means that the minimum available service is hourly.

Commuter rail networks are designed to do one thing and one thing only: move commuters into the city core to go to work in the mornings, and take them back home in the evenings. Commuter rail systems thus have very peak-heavy schedules; in the most extreme cases, such as the LIRR’s, this results in a one-way mainline at peak, precluding any anti-peak scheduling. It is for this reason that the LIRR is fundamentally useless for someone who lives in Jamaica but works in Garden City, despite the two being along the same line — their commute is against the grain, so to speak, and no service is offered in that direction.

A different approach is to provide all-day service: that is, a service backbone that results in guaranteed headways, with peak services added as an extra layer. Philadelphia’s Regional Rail network does this, with most routes having a minimum of hourly service at all times of the day. Scenario B is designed around having the same service profile: hourly services at the extremities converge into more frequent services in the trunk.

Clockface and Takt

There are two terms that one can come across in modern scheduling that can be very confusing: clockface and takt. This is because the concepts are applied in a similar manner. The essential distinction is: clockface refers to the practice of scheduling to a clock, i.e., if you have four trains per direction per hour, you can schedule to a :00 :15 :30 :45 clockface. Takt, on the other hand, comes from a Japanese phrase, takuto taimu, which was partially translated into German Taktzeit — from which the English takt (and not takuto) is derived — and means something akin to “measure time”. Think of musical measure, or a metronome. Takt refers to the measure of time allotted to do a task. So, for example, if you have four trains per direction per hour, the takt time allotted to each train would be 1/4 an hour, i.e. fifteen minutes and then the next train comes. Finally, headway refers to the time separation between individual runs (i.e. buses or trains or whatever) on a given route, and is related to these terms. That is: a :15 clockface equals a fifteen-minute headway equals a 4 tph per direction takt.

Building Up Frequencies

I’m not going to develop a detailed Scenario B schedule at the moment. But I do want to show the theoretical underpinnings of the schedule — the off-peak frequencies the trains operate at.

As a reminder, the system runs the following hourly services:

  1. L1: Trenton – Greenpoint
  2. L1: Trenton – Ronkonkoma
  3. L1: Sandy Hook – Far Rockaway
  4. L1: South Plainfield – Hempstead
  5. L2: East Stroudsburg – Hartford via Montclair and New Haven
  6. L2: Washington – Hartford via Morristown and Waterbury
  7. L2: Greenwood Lake – New Milford
  8. L2: Gladstone – New London
  9. L3: Allentown – Poughkeepsie
  10. L3: Lambertville – Hopewell Jct.
  11. L3: West Trenton – Newtown
  12. L3: Branchburg – Hawthorne
  13. L4: Amenia – Montauk
  14. L4: Vassar – West Hempstead
  15. L4: New Canaan – Long Beach
  16. L4: New Canaan – Babylon
  17. L5: Port Jervis – Wading River via Paterson
  18. L5: Suffern – Oyster Bay via the Bergen County Line
  19. L5: Mt. Ivy – Babylon
  20. L5: Paterson – Huntington
  21. L6: Kingston – Burlington
  22. L6: Sparta – Toms River
  23. L6: Nyack – Bay Head
  24. L6: Cornwall-on-Hudson – Long Branch

as well as the half-hourly service

  1. L1: Yonkers – Port Washington.

From this, we can see that we have “derived” half-hourly services, built around takt, along these segments:

  1. L1: Trenton – Rahway
  2. L1: Garden City – Ronkonkoma
  3. L2: Summit – Newark
  4. L2: Wayne – Newark
  5. L2: Milford – New Haven
  6. L3: Manville – Bound Brook
  7. L3: Beacon – Yonkers
  8. L3: Spuyten Duyvil – Marble Hill
  9. L3: Marble Hill – Hawthorne
  10. L4: Brewster – Mt. Vernon
  11. L4: Stamford – New Canaan
  12. L4: New Rochelle – Mt. Vernon
  13. L4: Lynbrook – Babylon
  14. L5: Paterson – Secaucus
  15. L5: Rutherford – Secaucus
  16. L5: Hicksville – Huntington
  17. L6: Cornwall-on-Hudson – Sparkill
  18. L6: Matawan – Perth Amboy

as well as two trains an hour, but not necessarily on a half-hour clockface, at

  1. L2: Lake Hoptacong – Denville
  2. L2: Newington – Hartford
  3. L2/L3: Danbury
  4. L1/L4: Jamaica – Rochdale – Valley Stream
  5. L5: Suffern – Glen Rock

Similarly, these derived half-hourly schedules lead to derived quarter-hourly schedules. Some of these have all four slots filled, such as

  1. L1: Newark Penn
  2. L1: Elmhurst – Jamaica
  3. L2: Newark Broad
  4. L2: Stamford – Norwalk
  5. L2: Sunnyside Jct. – New Rochelle
  6. L3: Bound Brook – Old Place
  7. L3: Marble Hill – Yankees Stadium
  8. L4: Mt. Vernon – Yankees Stadium
  9. L4: Valley Stream
  10. L5: Secaucus
  11. L5: Floral Park – Mineola
  12. L6: North Bergen – Secaucus
  13. L6: Old Place – Perth Amboy,

while others have a null slot, such as

  1. L1: Rahway – Newark Penn
  2. L1: Floral Park – Garden City
  3. L2: Milford – Norwalk
  4. L4: Jamaica – St. Albans – Valley Stream
  5. L4: Valley Stream – Lynbrook
  6. L5: Mineola – Hicksville
  7. L6: Sparkill – North Bergen,

and one has half-hour headways and a floating third service (L4/L5 Babylon), one has 4 tph and a second half-hour service “floating” with its own headway (L1 Sunnyside – Elmhurst), and one has 4 tph, but with a null slot and a floating fourth service (L1/L6 South Amboy – Matawan).

From these, we can see that the major trunklines have 8 tph per direction

  1. L1/L2: Kearny – NY Penn
  2. L3/L4: Yankees Stadium – Fulton Street
  3. L3/L6: Downtown Brooklyn – Old Place
  4. L4/L5: Downtown Brooklyn – Jamaica
  5. L5/L6: Secaucus – Fulton Street,

while one (L1/L2 NY Penn – Sunnyside) has 8 + 2 tph, the 2 tph floating with their own headways, and one (L3/L4/L5/L6 Fulton Street – Downtown Brooklyn) has 16 tph per direction, a new Old Fulton Street tunnel under the East River.

This also means that the inner-core combined-line trunks all have service frequencies, at all times, of 7:30 or better. And, as a rule, all service on the network is doubled during rush hour. This plan — the off-peak services outlined above, and peak services being these services all x2, will, when combined with the throughput standard signalling allows, determine how many tracks the network needs.

Next up: We will take a look at core infrastructure.

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s