Running Caltrain down the middle of the peninsula corridor, with HSR tracks flanking it on the outside, would maximize operating flexibility. For both HSR and Caltrain, the many pros and few cons of this "fast-slow-slow-fast" (FSSF) configuration were discussed before. In this configuration, each Caltrain station would have a single central island platform accessed via stairs, ramps and/or elevators from grade-separated streets or pedestrian tunnels running underneath and perpendicular to the tracks.The archetypal Caltrain station would consist of a 750-foot island platform (sufficient for 8-car trains), 30 feet across at its widest point. The tracks would slew apart and drape along either side of the platform along a gentle curve, with the platform tapering slightly at its ends. The technical term for such a track arrangement is a "wow" around the platform. Pedestrian access in the form of stairs and ramps could be built beyond the ends of the platform. Seen from above, the arrangement would look vaguely like an elongated football--hence the name, Football Island.
On Football Island, the typical station amenities would be shared among both northbound and southbound directions. One set of ticket vending machines, passenger shelters, benches, lighting, visual information displays, etc. would suffice to serve both directions. The platform space itself would be about twice as wide as today's Caltrain platforms, providing a safe space for waiting passengers well away from any trains that might speed past the platform without stopping. Access to and egress from the platform would occur at both ends and near the middle (total 3 places) to provide a safe waiting space without confined dead-ends. More people would be present on a platform that serves both directions, so passengers would be less likely to feel isolated or unsafe.
Underneath Football Island, cross streets (as typically found near Caltrain stations) would pass under the station, typically near the ends of the platform--although the design is flexibly adaptable to any local street configuration. Bus stops would be located right underneath the platform, allowing connecting passengers to switch between bus and train via a single flight of stairs (or a single ramp) without ever needing an umbrella during rainy season.
The station would connect into the pedestrian fabric of each town with six different approaches (3 paths under the tracks, each accessible from east and west.) There would never be any confusion as to which platform to wait on, and clear signage on the platform and trains would indicate the correct service direction to new users and regular commuters alike.
Football Island would be replicated at every Caltrain station for a consistent look and feel, with minor variations to accommodate the local street configuration.
Yes But...
The Football Island concept does not fit the stereotype of what an American commuter rail station looks like. That's why the people in charge of designing new stations for the peninsula corridor might initially be suspicious of the idea. Here is a list of objections they might raise.
- Platforms must be tangent (straight) to meet ADA regulations.
In today's regulatory environment, "curved platform" might seem like an oxymoron. Just like a turning semi-truck needs additional clearance on the inside of the turn, long train cars serving a curved platform need a wider gap to clear the edge of the platform. This eats into the maximum 3-inch gap permissible under ADA regulations. By how much? Football Island would be built on such a wide curve radius (10 km / 6 miles) that an 85-foot passenger car would have a maximum lateral displacement of 4.5 mm (3/16 inch), which amounts to just 1/16th of the permissible gap. For ADA level boarding purposes, Football Island is essentially a tangent platform. Unfortunately, the specifications for HSR (TM 2.2.4 section 6.1.3) limit platform curvature to a minimum of 20 km / 12 miles, and only under exceptional circumstances requiring special approval. - HSR passengers would be uncomfortable with all the twisting and wowing around Caltrain stations. Straight tracks are necessary for a smoother ride.
The 10 km curve radius (zero-degree, ten-minute curve in ancestral railroad units) is very gentle for the 200 km/h (125 mph) maximum speed envisioned on the peninsula. The curve could be fully compensated by less than 50 mm (2 inches) of superelevation on the outside pair of HSR tracks, something exceedingly unlikely to cause discomfort or motion sickness, let alone spill anyone's coffee. The inside tracks for Caltrain would not need any superelevation at all. Again, unfortunately, the specifications for HSR (TM 2.1.2) state right up front that "Over four changes in direction per mile shall constitute an Exceptional condition." That's all well and good at 220 mph, when a mile flashes by in 16 seconds, but this standard is overkill at a more sedate 125 mph. - Curved track is more difficult and expensive to maintain than straight track.
For card-carrying AREMA members accustomed to laying out freight tracks, this principle may hold true. Not so for high-speed passenger rail: the precise alignment and maintenance required to operate at 200 km/h (125 mph) is equally demanding on straight track and curved track. As to complexity of the alignment, we can safely say that ancestral 100-foot chains have been replaced by lasers, GPS and computer-driven tamping and lining machines that can dress track to millimeter accuracy, regardless of whether it is straight or ever so slightly curved as in the case of Football Island. The wheel-rail interface won't know the difference between tangent track and a 10 km (6 mi.) radius curve driven at just 200 km/h (125 mph); additional wear will be nil. - Football Island would require much more land, to provide clearance for the tracks to wow around the platform.
Not that much more.
Compared to a traditional arrangement with 16-foot outside platforms (blue lines), Football Island (red lines) requires 2220 m2 (24,000 square feet or 0.5 acres) of additional space. This extra space is shown by the area shaded green in the figure at right, assuming that the right-of-way boundary is 4.5 m (15 ft) from the nearest track center line.
Compared to yet another candidate configuration, a one-sided wow with three straight tracks and one track wowing around an island platform with a radius tightened to 7.7 km (to account for slower commuter train speeds), Football Island uses about 0.2 acres less land. See figure at left; the blue side-wow configuration uses additional area shaded green, minus the portion shaded gray. The green area is larger than the gray area, showing why the side-wow configuration uses more land than the Football Island configuration. - Placing an island platform between the tracks impedes passenger access.
While an island platform indeed prevents direct access along its entire length from the local area around the station, consider that a typical Caltrain passenger will use the same station twice per trip: once on each leg of the journey, using the northbound and southbound platforms once each. Therefore, even with outside platforms, the passenger must use grade-separated undercrossings on at least one leg of the journey. If you tally the number of stairs and the distance walked through access facilities on a roundtrip journey--an objective measure of accessibility--Football Island is no worse than a grade-separated conventional outside platform, especially if the station is elevated. - Nobody else does it that way.
Anybody in Silicon Valley would tell you that's no reason to be afraid to innovate. Nevertheless, there is a precedent as shown in the opening photo: the FSSF configuration with island commuter platforms is used to great advantage in Stockholm, Sweden, where the 200 km/h (125 mph) non-stop Arlanda Express runs on the outside tracks, with local commuter service on the inside tracks with island platforms. The photo above was taken from about 1:40 in this video. Another video shows an amazing side-by-side race with an Arlanda Express, shot from the cab of a commuter train; note crossovers providing access between slow and fast tracks.
Football island would enhance the peninsula commute while ensuring the smooth flow of local and express traffic, without requiring hulking flyover structures or stacked arrangements to provide flexible access between slow and fast tracks.
Posts
What does a "direction change" mean - does it mean a transition from one curve (or tangent track) to another curve?
ReplyDeleteAnother disadvantage of center island platforms is that they are not so great for passenger flows.
ReplyDeleteConsider what happens when a train stops to offload a sizeable passenger load. There is a crush of passengers coming down the stairs. Meanwhile, somebody wanting to get up to the platform to catch a train going the other way has to push their way through the huge crush of people coming down the stairs. It gets worse if that person has luggage or a bicycle.
This problem can be mitigated somewhat through the use of lots of escalators going in both directions, assuming space permits.
Nevertheless, there is a precedent as shown in the opening photo
ReplyDeleteI'd bring up Metra Electric, which apparently has been that way since the Exposition in 1892, but then someone would use it as a case for putting 6 tracks along the Peninsula...
What's the effect of putting the louder express trains closer to the edge of the ROW? A decibel here a decibel there adds up....
push their way through the huge crush of people coming down the stairs.
There'd be two platforms at the express stops. So at the local stops, where there'd be one platform, there would generally be less people.
@Drunk Engineer:
ReplyDeleteI've spent a lot of time on Italian trains. There's a lot of center platforms there, if only in stations with 4+ tracks. People instinctively divide the stairs into up and down based on how many people are going in each direction. It seems to work out fine.
If anything, center platforms use stairways more efficiently since you can afford twice the stairways serving a single platform.
Sizeable passenger load? Escalators?
ReplyDeleteWTF? We're talking about some minor stations here mostly anyway. San Bruno. Menlo Park. Bayshore. San Antonio.
And we're talking wider platforms and better stair access than any BART station anyway. About the same width as the SF CBD platforms, but with potentially better and easier -- no mandatory corralling through a central fare gated plaza -- better than Berkeley or Fremont or Orinda and the like.
With stairs and ramps. Forget maintaining escalators or, God forbid, elevators at lightly used stations.
Get real! This sort of stuff works, and works perfectly, and is wonderful for passengers and for train operations. Your northbound train gets diverted to run on the southboudn track for some reason? No problem. Walk 20 feet, and there is is. No muss, no fuss, no delay.
Wanna bet CHSRA and Caltrain will not ever consider this? It's not how my grandpaw build stations, so it's not good enough for me.
This effect can be seen at minor stations too. Neither Fremont nor Ashby BART have large passenger flows, but I can assure you (based on extensive personal observation) that stairwells do get congested. Congested enough to cause people to miss trains.
ReplyDeleteAbout the same width as the SF CBD platforms, but with potentially better and easier -- no mandatory corralling through a central fare gated plaza -- better than Berkeley or Fremont or Orinda and the like.
Stairway congestion to SF CBD platforms is bad, even without the fare gates.
@ Clem
ReplyDeleteI understand that this makes a lot of sense to you and others on this blog. You've convinced me that FSSF would be the right way to do this.
My question is, have you submitted any comments to this effect in the CEQA process? Has anyone on this blog done so?
If you haven't, then nothing recommended on this blog is ever going to be implemented.
@Peter, of course I have.
ReplyDeleteThe problem is that comments like these can be summarily dismissed over some specious objection, most likely relating to freight service. As best I can tell, right now FSSF is nearly off the table, if not already so.
FSSF works perfectly for freight.
ReplyDeleteAt most stations the scary FRA trains (which I bet will NEVER run, after we taxpayers are suckerd out of a billion dollars making space for them) will be well away from the platforms.
And they'll only be running between midnight and 5am. Caltrain says so!!!
What the heck is wrong with those idiots? Perhaps it is time to just kill of Caltrain altogether, because whatever replaces it, even if that is spelled B.A.R.T., can't be anywhere near as stupid.
which I bet will NEVER run
ReplyDeleteAh but they are going to be dumping garbage in Nevada eventually. It's the only "product" that's going to be shipped out but there's going to be garbage. They may politely call it recyclables but there's going to be garbage. Back of the beer stained cocktail napkin came up with 200 cars a day. As long as you are maintaining the ROW for outbound garbage you might as well ship in sheetrock, granite counter tops, asphalt, cement, beer by rail. Never going to be a lot of it but since the ROW is there why not?
Are you not paying attention, Adiron?? Catering to very limited amounts of heavy freight on the Caltrain ROW will add at least a $billion to the cost of totally grade separating the corridor due the need for super-shallow gradients, plate demands, and idiot FRA regulations. The higher the pricetag, the less likely the Caltrain/HSR project will ever be funded and completed.
ReplyDeleteThe Caltrain ROW currently sees very little freight due to the effective demise of the Port of SF (all shifted to the East Bay) and a very small, marginal, and shrinking manufacturing sector on the Peninsula, and even less freight is going to be required on this corridor in the future. Light freight will always be an option, but heavy freight should be banished from the corridor (it's almost gone as it is).
No need to ship beer on a short-haul train, when a distributor truck is so much more efficient and direct. Most freight ends up on a truck sooner or later anyway to reach its final destination, and since most freight will be going through the Oakland hub, it makes sense just to truck it over the Bay Bridge from Oakland. Oakland is already SF's freight hub, so why circumnavigate the whole bay for 100 miles on a shortline?
As for the trash, recycling in situ would be far more effective and better for SF's green credentials. Actually, recycling work is a good job opportunity for disadvantaged urban youths. Barges could also easily take any of the rest to the real, actual freight hub of Oakland and beyond.
most freight will be going through the Oakland hub, it makes sense just to truck it over the Bay Bridge from Oakland.
ReplyDeleteMost freight will be going through the Port Newark or Port Elizabeth, it makes sense just to truck it over the Verrazano Narrows Bridge from New Jersey. .... which is why the Port Authority of NY and NJ is going to spend 7 billion dollars to build a railroad tunnel between Jersey City and Brooklyn.
Lots of freight moves through Chicago. They can just truck it between the rail terminals.
Silly Los Angeles spending all that money on the Alameda Corridor project, they could have just trucked the stuff from the port.
I'm sure the people in Oakland will be thrilled to host a garbage transfer station. "Truck it to Oakland" works as long as there is capacity to do it. Shipping garbage from a transfer station on the Peninsula by rail to a dump in Nevada is going to be cheaper than sending all those trucks to Oakland.
Shipping garbage by rail is the low hanging fruit when it comes to congestion relief. And it's cheaper, some of the reasons NYCDEC is pushing hard for the tunnel to New Jersey.
As for the trash, recycling in situ would be far more effective and better for SF's green credentials.
Where you gonna put the aluminum smelter? And how do you ship the smelted aluminum to the can plant? Unless you find space for a can plant somewhere in San Francisco and bottling plants to fill the resulting cans. Glass furnace? and you still have that problem of shipping the raw glass to a plant where it can be turned back into bottles and jars. Paper can be recycled easily. How about a nice pulp plant on the Embarcadero? And how do you ship the paper to the cardboard box plant? Recycle as much as you can you still have to ship the recyclables somewhere, they don't disappear into into a wormhole when the recycling bin gets emptied then magically appear at the factory that uses the recyclables.
Barges could also easily take any of the rest to the real, actual freight hub of Oakland and beyond.
I'm sure the people whining about how their precious condos can't be taken for the HSR station will just roll over and clap their hands when someone suggests building a garbage scow dock a block away. Not to mention how the people of Oakland will feel about hosting a garbage transfer station and a dock.
which is why the Port Authority of NY and NJ is going to spend 7 billion dollars to build a railroad tunnel between Jersey City and Brooklyn.
ReplyDeleteHahahaha! Care to guess how old this idea of a rail freight tunnel between New Jersey and New York is??? Look into the history. It was the founding idea behind the creation of the Port Authority in the first place!!!! What has taken them so long??? Have the garbage piles and empty shipping containers gotten so bad that they are finally getting around to it!!! This is truly a laugh!
The Port of San Francisco is effectively dead as a cargo port. What's all this diversionary nonsense about Chicago's status as a continental railhub and LA's Alameda Corridor? The Port of SF is not the Port of Long Beach, the Port of LA, or even the Port of Oakland. Look at a map! Hardly any freight moves through San Francisco or the Peninsula. SF and the Peninsula just consume the final distributed end-products. For post-industrial places like SF and the Peninsula, delivery and distribution trucks are more than adequate and even more efficient. Also, light rail freight is still an option.
As for the point of recycling, local recycling breaks down the trash into useful material segments. The bulk has been separated into smaller, discrete units of paper, metals, glass, etc. Some can be reused in situ with small-scale light industrial processes. It's a good way of re-using SF's derelict industrial spaces on its southeast shore, and it's actively being promoted as a "green jobs" initiative for decaying industrial areas. Other materials can be easily handled by a truck, which will bring its specialized cargo directly to a reprocessing plant (no clumsy out-of-the-way rail transfers). Trucks aren't evil. ;-) For the stuff that simply can't be recycled, it can be collected and shipped on a barge across the Bay, which is still more direct than a train going all the way around the Bay.
By the way, Oakland is more than capable of handling freight and trash. Do you have any clue about the Bay Area?
Dear Adirondacker12800,
ReplyDeletePlease consider either spending some time on the SF peninsula with your eyes open, or looking at a map before holding forth either on the Port of San Francisco or goods movement in the San Francisco Bay Area.
And then feel free to post your considered opinions about the vital role for and economically justifiable costs of freight trains on the HSR-with-crumbs-left-over-for-Caltrain-maybe corridor in one of these places.
Thanks!
The Cross-Harbor Tunnel is connecting New York City, Long Island, Westchester, and southern New England with the mainlines in New Jersey. Freight on the Peninsula connects San Francisco with the mainline. It's this factor of 20 difference in population that makes one heavy freight accommodation a reasonable idea and another insane.
ReplyDeleteHow far along is the original Caltrain electrication project anyway? (in terms of design and environmental clearances). It kinda sounds like State of California just got a bunch of funding for a bunch of shovel ready work which is now "on the fast track".
ReplyDeleteAre Caltrain projects (designed for Caltrain (pre-HSR)) going to get to the front of the line soley because its shovel ready, job-creating ASAP?
In which case, is the 'best' configuration for HSR on four tracks - all an academic exercise in futility? What DID just get funded anyway?
Fine use trucks. In the 2040 MIS for yet another widening of 101 they can eliminate "use more rail freight" from the alternatives because freight was eliminated from the ROW in 2015. The conga line of garbage trucks to the transfer stations can use the HOV lane in the dead of night.
ReplyDelete@anon: according to the latest JPB brief, the electrification project reportedly has federal clearance (FONSI from FTA) but CEQA still plods along. Shovel-ready San Bruno is on the fast track with construction starting within the next few months. Warts and all.
ReplyDelete@Adirondacker: the entire volume of freight on the peninsula, if put on 101, would add just 25% to the existing traffic of 5-axle trucks. Of course, 5-axle trucks are but a small sliver of the traffic on 101: they are vastly outnumbered by 2-axle, 3-axle and 4-axle trucks, not to mention legions of cars. So yeah, it's not entirely crazy, although quite un-green.
the entire volume of freight on the peninsula, if put on 101, would add just 25% to the existing traffic of 5-axle trucks.
ReplyDeleteOnce the ROW is lost it's never coming back. You are assuming the population on the Peninsula will remain the same, the amount they consume will remain the same, their income and interest in driving on 101 or 280 will remain the same in 2040, 2075 and 2175. Good luck with that. Not really my problem. When I visit I'm quite content to use BART, Muni and GGT until I get up to Santa Rosa where my cousin lets me borrow the Miata.
Once the ROW is lost it's never coming back. You are assuming the population on the Peninsula will remain the same, the amount they consume will remain the same, their income and interest in driving on 101 or 280 will remain the same in 2040, 2075 and 2175.
ReplyDeleteNope, we're considering that the amount of heavy industry on the Peninsula (virtually nil) will indeed in all likelihood remain the same.
And garbage can go on a barge; the port of Oakland is a vast facility; no one in Oakland will notice or care if there's a transfer facility for SF garbage there, and it will provide additional jobs and revenue.
Seems to me the FSSF with island platforms design is almost required if the tunnel crowd gets its way - you could build an underground local station as one big box; with SFFS you'd need two boxes on either side or complex underground flyovers to make everything line up on one platform.
ReplyDeleteEric, stations are built as single boxes even when there are side platforms. However, island platforms have the advantage of requiring less station volume, which reduces construction costs.
ReplyDeleteAs far as I understood, the argument for running the freight on the slow track was superelevation for the express would not allow running heavy freight on the express.
ReplyDeleteBut if the freight is only going to be running during the HSR curfew, crossing the eastern express track to reach the eastern slow track as a freight track at night is not an active crossing.
Even if Caltrain services were to continue all night long, they'd be at low frequency, and could stay on the western slow track as a bidirectional line, using the western express for any required passing movements.
For visual amenity, that puts the heavier weight on the overpassed to the inside, so the express tracks can have the more airy supports permitted by 17 metric ton axle loadings, even at relatively high speed.
Indeed, 22.5 metric ton axle loadings would allow everything but the Abrams tanks ... and if they need the Abrams tanks in San Francisco itself, as opposed to getting to a port for loading, probably best to drive them up the Peninsula anyway.
"the argument for running the freight on the slow track"
ReplyDeleteI think "argument" is too strong and meaning-fraught a word for the processes that are at work here with the World's Finest Railway Engineering Professionals.
Anyway, let's look at the Caltrain line.
Assuming 200kmh operating speed between Santa Clara and San Bruno -- and I claim that is just Not Going To Happen in the real world, but that doesn't affect the ... processes ... at work with the WFREPs -- then the worst curvatures will be three successive 2000m radius curves in San Mateo, between San Mateo and Hillsdale stations.
(They aren't 2000m radius today, but they can and ought to be. If the WFREPs can't manage even that, then they should do us all a favour and shoot themselves.)
At 200kmh, the balancing superelevation for R=2000m is u_0 = 221mm.
Now AREMA -- ALL HAIL THE SACRED WFREP STANDARD -- likes 5 inches (= 127mm) maximum for its lovely freight trains.
So that would, assuming an unrealistic 200kmh, give us a cant deficiency u_f = 94mm = 3.7 inches.
Nothing to worry about.
In fact the standard German design superelevation target for mixed traffic lines (RiL800.0110 6.5) aims for u = 6.5 * V^2 / R, which in this case comes out to 130mm.
So our wonderful WFREP AREMA maximum and a first world standard norm happen to come out almost exactly the same in this case.
In other words, there's no problem.
In other words, the World's Finest Railroad Engineering Professionals are Full of It. As Usual.
As far as I understand it, Caltrain has been systematically removing center island stations -- wasn't the Palo Alto station center boarding (sorry if I'm wrong about this)? I think Caltrain's major concern was that passengers could be at the center platform while non stopping baby bullets passed in both directions at the same time at 70 mph. Truthfully, it is a little disconcerting even currently when a non stopping baby bullet or express passes a station you are at. There's a lot of wind generated, and while I'm sure it is safe, it certain doesn't feel all too safe.
ReplyDeleteWould an FSSF configuration mean that all non stopping trains would always switch to the outside F tracks? Or would this cause a scheduling nightmare? Is there the possibility of four non stopping trains passing a station at the same time?
It's kind of weird this would have been done at Palo Alto, where all Baby Bullets stop.
ReplyDeleteNot all Baby Bullets stop at Palo Alto. Most do, but some skip PA and stop at Menlo Park instead.
ReplyDelete@ RobBobRob
ReplyDeleteClem's not talking about the center boarding platforms like Caltrain currently has. He's referring to an island platform similar to the ones at San Jose Diridon and 4th & King.
It's kind of weird this would have been done at Palo Alto, where all Baby Bullets stop.
ReplyDeleteCalifornians are conditioned to get to the other side of the station on the station's tracks. They probably took it out because they feared that too many pedestrians who cross the tracks at the station all the time would cross just as the express blasted through.
....you've seen the surveillance camera video from suburban Chicago. It's aimed at the pedestrian grade crossing in the station. The gates are down and someone decides the gates are down because the local is in the station. They the video ends as she darts onto the express track and the express comes into the frame. ...
I was talking about island platforms similar to Belmont, roughly 30 feet wide.
ReplyDeleteNot to be confused with the old, narrow center boarding platforms, accessed at grade, that were removed in order to get rid of the "hold-out rule", which forbids two trains (stopping or not) from simultaneously occupying such a station.
Not to be confused with the old, narrow center boarding platforms, accessed at grade, that were removed in order to get rid of the "hold-out rule", which forbids two trains (stopping or not) from simultaneously occupying such a station.
ReplyDeleteClem, is the holdout rule still in effect in station such us South SF where a SB is at the station pickup passengers on the west side, while a Baby Bullet is on the NB track passing the station?
That configuration sounds like it wouldn't be affected by the 'rule'.
"Is the holdout rule still in effect in station such us South SF where a SB is at the station pickup passengers on the west side, while a Baby Bullet is on the NB track passing the station?"
ReplyDeleteYes.
The inter-track "platform" (to use the term charitably) at South SF is just a strip of asphalt between closely-spaced running tracks.
Anybody exiting a train onto that narrow strip would be in grave danger from any train moving on the adjacent track.
In contrast, a wide (circa 30 foot) island platform, such as at Belmont, provides a safe boarding and waiting area clear of the tracks. (Imagine! Just like in the 20th century!)
What might be confusing the issue is another point, that Caltrain inexplicably still builds stations with pedestrian crossings at grade. (Hello! The 19th century is calling and wants it stations back!) Just as for outside boarding platforms, Caltrain's "hold out" safety rule equires that all such crossings be ding-ding-ding belled and have crossing arms and blinkenlights.
A difference between the numerous existing outside boarding platforms and a hypothetical ground-level, no pedestrian overpass/underpass island platform would be that all pedestrian routes to the platform would require crossing a track. (No such stations exist, but Caltrain has a design for how they would be laid out. South SF was going to be reconstructed that way, but Caltrain pulled the plug on it in favour of wasting $300 million of your tax dollars completely screwing up San Bruno instead.) Anyway, as long as grade crossings have crossing gates, there's no hold-out rule issue.
But this is all irrelevant.
The best and most natural and most convenient and most community-friendly and only sane way to build stations at nearly every location is to elevate the tracks, put an island platform (or platforms, at major stops), and have crossing-free access from ground level (drop-off, parking, buses, streets) right up to the platform.
Summary: the "hold out rule" won't be an issue because there won't be any pedestrian grade crossings of the tracks.
Richard are you sure?
ReplyDeleteAnybody exiting a train onto that narrow strip would be in grave danger from any train moving on the adjacent track.
In the case of a SB train discharging passengers, they'd be stepping on the side and not onto that narrow strip. More so, the NB train passing through the station would be buffered by the SB train.