If they pull it off

From the Red Line
Published in
8 min readMay 4, 2024

The LTA appears to be pushing forward with the plan to merge the Changi Airport branch into the TEL.

If they succeed, that will have wide-ranging repercussions for what the modernization of our MRT lines will look like in future. While upgrades to Tanah Merah and Expo stations are straightforward, converting Changi Airport T1–3 station to accept TEL trains will be challenging, and long ago I described some of the challenges with the station here.

That’s also not to mention the complications with the tunnels between the stations as well. In any case, it appears they’re pushing forward with those plans, with a cryptically named contract being put up for tender. After all, it has been about four years since the engineering study for a “TEL Extension” was awarded to Arup and SAA Architects — key partners in the T5 design consortium.

For what it’s worth, Shanghai Tunnel Engineering Company, as contractor for Contract T316, will already build the connection from Changi T2 to T5 — perhaps including the final link up to the current Changi Airport station, and also to be completed by 2031. From there, one can then expect the final link to be built by the airport, to connect to the T5 Ground Transport Centre where a CRL station will also be sited.

Old specifications

The Changi Problem isn’t the only structural problem the LTA engineers will face. But as a brief recap, it concerns the structural design of the Changi Airport station as it currently stands — with supporting pillars placed between the train tracks and the platforms. Space is left between the pillars for train doors, but the windows in the middle of the car — where the middle door would be on 5-door TEL cars — essentially face a concrete wall. Here’s what it looks like — the space between the open platform doors are much wider on older lines than they are on TEL.

TEL doors open at station (source: LTA)
Video screencap of EWL train with doors open (source: Singapore Trains Channel)

Like the Initial System before it, the tunnels between Expo and Changi Airport do not have emergency walkways, which have become a standard for automated MRT lines since the construction of the NEL. Perhaps the NSEWL doesn’t yet need this feature, even despite most daily operational tasks automated by the CBTC system, as it still retains the need for a driver to supervise train operations.

Emergency evacuations on Singapore trains may use ramps that fold down from the front of the train. But the emergency walkway is still useful for fully automated train operations, as a member of staff can walk along the walkway to reach a disabled train and perform recovery operations — hopefully to get the train moving again. To be fair to the TEL, it is not like they are unused to long tunnels, as the tunnels between Woodlands South and Springleaf are as long as those between Expo and Changi Airport.

This could be a reason why the LTA and SMRT chose not to totally remove the driver; even though they can reasonably also automate the depot as part of modernization works being done to the signalling systems inside Bishan and Ulu Pandan Depots — Tuas and East Coast being delivered with the new systems from day one, and Changi Depot will close eventually anyway. And even if manual operation was retained inside depots, it may have been possible for trains to operate autonomously on the main lines and cabs left empty.

So if they are constrained by ground infrastructure, it also complicates any efforts to automate the NSEWL. Thus, the conversion of the Changi Airport Line can be examined as a testbed; the experience gained here can inform future upgrading projects. After all, if they do it once, they can do it again; and it may be necessary sooner than later to allow some trains to operate unmanned if we’re ever in a position where we can’t find train drivers. Or perhaps they may yet find a way to expand the tunnels or cram in an emergency walkway somehow.

Alternatively, the cop-out option for Changi Airport station, if they cannot adjust the platform columns, could be simply to leave the middle door of every car closed, since they open right behind a pillar. I’m not sure if fire safety regulations might permit that on a permanent basis, but that they’ve taken so long to analyse the requirements, maybe they’ve found a way that may be acceptable to the relevant authorities. TEL trains are already capable of isolating train doors should the corresponding PSDs be nonfunctional, so this can just be an extension of that work.

Oops (image by me)

But what this sets is precedents. Especially on the DTL, it may be possible to extend platforms to operate longer trains — quite a few stations, like Little India and Bayfront, have excess length of platform that are walled up, and on many other DTL stations it may be possible to extend the passenger waiting areas into what are currently service areas, keeping doors closed where it’s not possible to extend platforms. If they can do it on TEL, they should be able to do it elsewhere, and I wouldn’t be surprised if questions were asked. Perhaps I may be the one asking them.


As the works at Tanah Merah take shape, the scale really only makes sense when you realize that perhaps, this was planned from day one. Door nameplates in expanded areas of the station reveal that space has been set aside for the future installation of TEL systems. Extensive mechanical and electrical spaces beneath the new platforms may thus also have space carved out for the future extension of the TEL to Tanah Merah, apart from what’s displaced from the construction of the new east concourse and new exits.

The proof is in the pudding. (photo by me)

That said, from the site showarounds, it appears that works under Contract T3206 will not take place at Tanah Merah station — only at Expo and Changi Airport stations, and an intermediate service building. It does raise the question on what exactly needs to be built at these stations. Are we talking about additional services rooms for TEL systems?

Much thought will also have to be placed on the behavior and performance of TEL trains on the elevated section between Expo portal and Tanah Merah. While this may already have been considered back when it was proposed for the T251 fleet to operate on the JB-Singapore RTS, and that Mandai Depot is also already in the open air, at the bare minimum the work will have to be revisited when Alstom and other systems contractors are remobilized to fit out TEL systems, and trains may need to be tested again.

The reason why the LTA may not yet be saying anything much about the works may perhaps be because these may be design and build contracts. The contractor who eventually wins the job may be able to bring to bear their experience and propose a better solution than the LTA and their consultants. As we’ve seen with other lines, there are plenty of cases where the proposed concept designs drawn up by the LTA and released at tender award end up differing considerably from what the contractor actually builds.

Some contractor may be able to find a way to modify the station structure itself; to create a clear 93m platform length for TEL trains to stop at. After all, depending on the current structural design, it may not be as simple as leaving the middle door closed, especially if the new positions of the TEL train doors also complicate the installation of platform screen doors. After all, TEL platform doors are much closer together than on the NSEWL, as mentioned above.

Or we’ll never hear about this again

It may never happen, though. Perhaps the addition and alteration works may be just that — to improve the infrastructure to permit more EWL trains to be run, be it power or ventilation. Maybe they might end up building a third set of platforms at the T5 GTC, and then just extend the line as is to T5, over the Contract T316 tunnels, and meet the TEL there. This also avoids the disruption that will come with the inevitable closures needed to adapt safety-critical control systems — a lesson Sydney is learning right now.

It may perhaps also provide a space for the TEL to be further extended east to any new developments in land currently being reclaimed there; or even to just continue on to T1–3 using another alignment that allows MRT service to also connect to T4. Though this may not be necessary with Changi Airbase built east of the airport.

And ultimately, is it worth it? The old Changi Airport through service was stopped because residents in Pasir Ris and Tampines had lesser train service. But now that Tampines has the DTL and will also get the CRL at Tampines North, through service can and perhaps should be brought back, with some trains redirected to the airport instead of sending the full service to Pasir Ris. Many Tampines and Pasir Ris residents may find that these two rail lines serve many purposes better and eventually move away from the EWL.

Ultimately, what will the service look like? This project may turn the TEL into Singapore’s single longest MRT service. By itself the TEL is 43km long and the Changi Airport Line 7km; the distance between Sungei Bedok and Changi Airport via T5 is approximately 8–9km. String them all together and you get a ~59km long line, perhaps longer than the final CRL service from Changi T5 to Gul Circle.

Try guessing where the T5 station will be (source: URA Long-Term Plan Review)

But just like how the CRL will also have a short turn service that likely won’t go to the airport, it may also not make sense for all TEL trains to go to the airport. It wouldn’t be surprising if every alternate train ended at Sungei Bedok, especially with a TEL peak service that could potentially be less than every 2 minutes between trains. Even so, faster TEL trains can also speed up journey times; and depending what service levels after 2026 look like, might be an improvement over the EWL shuttle.

Then again, I suppose, a direct MRT service to the city centre itself from every terminal should already be welcome. Especially since it’s not a hilariously overpriced express train that doesn’t stop anywhere useful.

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From the Red Line

Sometimes I am who I am, but sometimes I am not who I am not.