Why no center platform at busy stations.

Just thinking bout quick loading , and note that it is not common for stations to have platforms on both sides of the track . This would allow unloading / loading to occur on both sides of the train at once. On a double track station this would just require one extra center platform to allow double sided boarding for both tracks.
I can remember both sides doors opening on the London tube , but can't remember which station? I'm thinking Waterloo???

LIRR has this at Jamaica Station. Trains coming from or going to Penn Station will use a single track with platforms on both sides to allow transfers to/from other lines.

The NYC subway uses this design on certain lines and certain stations to allow local and express train cross-platform transfers.

This is typically called the Spanish Solution: https://en.wikipedia.org/wiki/Spanish_solution.

Building extra platforms, particularly underground, is expensive, which is probably why there are relatively few of them.

When designing a line from scratch and accepting that you need grade separation between pedestrians and trains, a center platform makes the most sense. If you’re overlaying service on an existing rail line, you don’t have much commuter service planned, the flow is exclusively directional, or you don’t have to/want to build a pedestrian bridge or tunnel, it is cheaper to build two side platforms and not realign the existing tracks.

59th-Columbus Circle on the IND subway had a center platform, now out of service.

The Hudson & Manhattan Railroad used this scheme at their terminal stations. This is still in use at 33rd street, Hoboken, and Newark (boarding only). Sadly, the Port Authority eliminated this when it replaced the Hudson Terminal station.

gprimr1 wrote: ↑Mon Jul 06, 2020 12:27 pm LIRR has this at Jamaica Station. Trains coming from or going to Penn Station will use a single track with platforms on both sides to allow transfers to/from other lines.

The NYC subway uses this design on certain lines and certain stations to allow local and express train cross-platform transfers.

GP: The LIRR platforms at Jamaica that allow transfers between
trains are Platforms A and B serving Tracks 1, 2 and 3 westbound to
Penn Station and Atlantic Terminal Brooklyn primarily.
Island Platform C serves Tracks 4 and 5 and are used during peak hours
primarily - AM Peak westbound, PM Peak eastbound.
Platforms D and E serves Tracks 6,7 and 8 eastbound to Long Island
destinations on various branches.
Newly-constructed Platform F - which is not yet in service - is slated
to be used for an Atlantic Terminal Brooklyn - Jamaica shuttle service.
The tracks serving Platform F will be 11 and 12 (Tracks 9 and 10 are
through tracks in between allowing limited Jamaica bypass)

Hicksville and Babylon are both three track stations with two island
platforms that have been used as intermediate transfer points between
lines or electric (west) and diesel services (to the east) respectively.

A prime example of a busy three track NYCT Subway route is #7 Flushing
Line east from Queensboro Plaza to Flushing Main Street. The express
stops on the three track segment are 61/Woodside, Junction Boulevard
and Mets-Willets Point (Citi Field) on the way east to Flushing Main Street.
(FMS is one of the busiest subway stations in NYC outside Manhattan)

These are the best examples of a two platform three track format that
I know of and recall...MACTRAXX

There are a couple reasons:

(1) Expense as noted above
(2) Right of way considerations... where have been island platforms been added on commuter rail lines as of late? The most recent example is Paoli, but that is sort of an ideal situation for an island platform - the right of way is wide enough for 4 tracks and it dropped to 2 tracks just west of the station. A great example of a place where an island platform would add value is Jenkintown, but the right of way does not exist.

Let's look at Metropark, located along Amtrak's NEC in Woodbridge Twp, as an example. Metropark has two side high level platforms that are on a curve and that was the only solution over building center island platforms there. It's one of the busiest suburban park n ride lot stations along the NEC. NJT decided with the Metropark station arrangement since they own the station. It would have been great for the high level platforms to be center island as that would enable more Amtrak trains to stop there during rush hour, especially the Acelas.

I mean, Metropark really should have been built with three islands and two side platforms. It should also have been built on the Middlesex Turnpike right-of-way thereby eliminating the curve, but who’s counting?

Thanks for the replies all. The Spanish link is interesting. I do recall thinking there were a lot of platforms in Spain, (any decent size station would have more than 2) , but I can't recall seeing wether they served more than one platform each . Probably more interested in looking at the Chicas in those days .

njtmnrrbuff wrote: ↑Sun Jul 12, 2020 2:19 pm Let's look at Metropark, located along Amtrak's NEC in Woodbridge Twp, as an example. Metropark has two side high level platforms that are on a curve and that was the only solution over building center island platforms there. It's one of the busiest suburban park n ride lot stations along the NEC. NJT decided with the Metropark station arrangement since they own the station. It would have been great for the high level platforms to be center island as that would enable more Amtrak trains to stop there during rush hour, especially the Acelas.

mtuandrew wrote:I mean, Metropark really should have been built with three islands and two side platforms. It should also have been built on the Middlesex Turnpike right-of-way thereby eliminating the curve, but who’s counting?

Buff and MTUA: Metropark Station was conceived in the late 1960s as
part of the Metroliner Project and built under a partnership between
NJDOT, USDOT and the Penn Central Railroad. The station opened in
November 1971 - when Amtrak was just 6 1/2 months old and was one
of two new suburban stations on the Northeast Corridor built during
that time period - the other was Capital Beltway, MD (relocated and
replaced in Fall 1983 at New Carrollton, MD) for Metroliner Service.

https://en.wikipedia.org/wiki/Metropark_station

The location chosen for Metropark Station was were the NEC crossed the
Garden State Parkway at GSP exit 131 and at mile 24.6 from Penn Station
New York at Iselin (replacing Iselin Station less than one mile east) which
is between Rahway (mile 20.8) and Metuchen (mile 27.2) on the NEC.

Virtually all of the commercial and office development in the area was
built after the station opened - the planners back in the day had no idea
that the area would grow as it has and that rail ridership on the NEC
was going to increase by leaps and bounds over the following decades.

There was not room - or more importantly funding - to build anything
other than the two platform station that was constructed on the NEC.

Keep in mind NJT was created in 1979 and would not directly operate
commuter trains until 1983 - NJDOT subsidized rail service in NJ by
contract operation of the former PRR NEC service by PC (later Conrail
April 1, 1976-December 31, 1982) before NJT took control.

Metropark Station is a prime example of a rail success story especially
taking note to the era (late 60s/early 70s) in which MET was built...

MACTRAXX

Metropark is situated at a great location. Yes, it's right off the Parkway. It's extremely close to other busy roads-of course, the station is along Rt. 27. It's not far at all from Rt. 1 and 9 and the Turnpike. Many people reverse commute to MET on NJT given the fact that there are so many office parks close by. It's pretty rare to have robust transit serving nearby suburban office parks. Of course, many Amtrak trains stop at Metropark. It's a great station for a person who lives in the central part of the state who doesn't want to drive to a big city station, especially to get Amtrak. Metropark is very close to Staten Island as well so there are probably many people who live in Staten Island who drive to Metropark to use Amtrak to head to DC.

You have the problem of freight train clearances with any high level platform including center platforms And to addd a kicker if Auto train uses these tracks the auto carriers will not clear. Holds back any future auto train service. Am very interested in how Bright line's movable walk ways on the cars hold up.?

In Munich in the 1970's a double-track S-Bahn tunnel was constructed beneath the city center, with five intermediate stations, each having two side platforms and one wide center platform. An arriving train would first open the right-side doors, permitting detraining passengers to leave the side platform by the (up only) escalators; a few seconds later the left-hand doors would be opened, permitting boarding passengers, who had reached the center platform by the (down only) escalators to enter, along with transfer passengers who had arrived on a preceding train. Expensive to construct, but probably less so than a four-track line, and shortened the dwell time considerably--essential with a base frequency of around 18 trains per hour in each direction.

I think I remember that at Chambers St. in New York the C (8th Ave. local) terminated at an island platform with two tracks, and a side platform on the opposite side of each track; a terminating train would open the doors at the side platform, and then after most of the passengers had left, the doors were opened on the side of the center platform, to which all boarding passengers had been directed.