The following fairly simple argument shows why Hillsdale is the only feasible overtake location on the Caltrain line, and why Caltrain's major civil works should be focussed very, very stringly around (possible phased) of construction a mid-line amplification around a four-track, two-island-platform Hillsdale station.

The final suggested operations pattern/infrastructure I describe below is shown in this diagram.


My starting assumptions are always that:

In essence, most of the above points reduce to "if it's good enough for the Dutch and the Swiss and the Germans it's good enough for me", or, "copy what has been shown to work", or, "emulate, don't innovate".

Timetables should be memorized ("express at 17 and 47 past the hour, every hour"), not carried around and constantly consulted. Deciding whether to board a train should be a trivial yes/no decision ("is my station served by express trains or only local trains?"), not an error-prone and intimidating consultation process.

Slight variations to strict service pattern regularity are possible in special cases. Adding 22nd Street stops for expresses in one direction only in AM/PM is the only one that springs to mind.

Supplemental peak trains in addition to the clockface might have customized stops (driven either by market demand, infrastructure inadequacies or a combination), but the base service regularity is non-negotiable.

Again, if it works for the people for whom things demonstrably work, it's good enough for me.

With only two train types, both operating predictably and regularly, we can provide scores of competitive trip times, without operating a mess of different customized train patterns.
This is simple, it's clear to riders, it's easy to operate, and it's much more efficient to operate (more people served better by fewer trains, combined with "good" trains for a given O+D operating minimum every 30 minutes rather than every hour for today's ad hoc collection of stopping patterns = better loadings = better revenue/cost.) It's also pretty clever. Lastly, people already know how to change trains at MacArthur station on clockface-scheduled BART with zero time penalty and near-100% reliability, one is not attempting to impose something foreign or suspiciously newfangled on the Sophisticated Bay Area Transit System.

OK! So those are the assumptions. I've never seen anything to indicate they're not the right ones!


So, building on that, the Major Stops are -- and I think this is pretty non-controversial, especially since we're guaranteeing far better service to all stations, including Burlingame and Belmont, with this plan:

The overall major/minor stop pattern is:

(TRANSBAY)
MISSION BAY
22nd Street 4 intermediate local stops
Bayshore
South San Francisco
San Bruno
MILLBRAE
(Broadway, within sight of Burlingame, closed) 2 intermediate local stops
Burlingame
San Mateo
(Hayward Park, within sight of new Hillsdale, closed)
HILLSDALE
Belmont 2 intermediate local stops
San Carlos
REDWOOD CITY
(Atherton, of no utility, closed) 1 intermediate local stop
Menlo Park
PALO ALTO
California Avenue 2 intermediate local stops
San Antonio
MOUNTAIN VIEW
Sunnyvale 3 intermediate local stops
Lawrence
Santa Clara
SAN JOSE


So, here's the simple argument, at last!

It comes down to this simple table, explained more below:

MISSION BAY 468911
MILLBRAE *2457
HILLSDALE 2*235
REDWOOD CITY 42*13
PALO ALTO 531*2
MOUNTAIN VIEW 7532*
SAN JOSE 108653

Now I claim we can model the run-time penalty for making a local stop versus running through a station as an express acceptably accurately as a constant per stop, given Caltrain's comparatively flat and comparatively straight route, and assuming station spacing of 1.5 miles or better. This penalty is somewhere around 2.0 minutes at present, and should decrease to somewhere around 1.5 minutes in the future under even unambitious operations/rolling stock/platform improvement scenarios. (1ms-2 braking/acceleration = 2.2mph and a top speed of 35ms-1 = 78mph, combined with 30 second dwells, both easy goals, gives a 60 second penalty. So we're can imagine being in the 90 second ballpark. The same direct calculation with present-esque circa 0.5ms-2 "performance" and circa 1 minute dwells, pencils out correctly at 110 seconds stop penalty.)

So let's sketch out what happens when different major stations are chosen as the overtake location.

If, for example, Millbrae is the overtake station, then at the time a southbound local starts to decelerate for San Bruno should be 1 stop penalty period ahead of the overtaking express; 2 penalty periods ahead at South SF, 3 at Bayshore; 4 at 22nd Street; and 4 at Mission Bay (where the express also stops).
Heading past the overtake, by the time it slows for Hillsdale it will be 2 penalty periods (corresponding to Burlingame and San Mateo) behind the express. By the time it reaches San Jose it will be 10 local penalty periods behind.

Putting this all together in tabular form, with entries corresponding to penalty periods that an express ought to be behind or ahead of a same-direction local train at a particular stop, we arrive at the table above.

Now, to be realistic, given the Egregious Right-of-Way Sabotage Campaign of the period 1992-1999, it is today quite infeasible to construct express/local coordinated-overtake (four tracks, two island platforms) at either Millbrae (ROW given away to BART) or Mountain View (ROW given away to VTA) at any time in the forseeable future.

So let us consider only the three cases of Hillsdale, Redwood City and Palo Alto from here on.

For a stop penalty of 1.5 minutes, the above translates to:

MISSION BAY 9.012.013.5
MILLBRAE 3.06.07.5
HILLSDALE *3.04.5
REDWOOD CITY 3.0*1.5
PALO ALTO 4.51.5*
MOUNTAIN VIEW 7.54.53.0
SAN JOSE 12.09.07.5

With such (optimistic) train performance, the above shows that no additional scheduled express/local overtakes should take place on the Caltrain line for local headways of greater than 10 minutes.

Buy high-performance trains and operate with a lot of discipline (two corners of the famous Swiss "rolling stock"/"service plan"/"infrastructure" Magic Planning Triangle) and one need construct only one overtake location line-wide, at a choice of one of three locations.

For a stop penalty of 2.0 minutes:

MISSION BAY 12.016.018.0
MILLBRAE 4.08.010.0
HILLSDALE *4.06.0
REDWOOD CITY 4.0*2.0
PALO ALTO 6.02.0*
MOUNTAIN VIEW 10.06.04.0
SAN JOSE 16.012.010.0

For a stop penalty of 2.5 minutes:

MISSION BAY 15.020.022.5
MILLBRAE 5.010.012.5
HILLSDALE *5.07.5
REDWOOD CITY 5.0*2.5
PALO ALTO 7.52.5*
MOUNTAIN VIEW 12.57.55.0
SAN JOSE 20.015.012.5

This shows that a 2.5 minute local stop penalty combined with reasonably frequent service results in excessive capital costs (a bad 1940s choice of "rolling stock" compromising the "infrastructure" and "service plan" corners of the Magic Planning Triangle.) I claim that it is self-defeating to make any plans for significant expansion of Caltrain service or major investment in Caltrain infrastructure under such a train performance assumption -- the wasted cash involved would be better spent building BART to Santa Barbara or something.


I claim that overall the Hillsdale overtake pattern is the optimum realistic and feasible service pattern for the Caltrain corridor, for the following reasons:


-- Richard