From the Red Line
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From the Red Line

The Sentosa Express

Is the Sentosa Express capable of what is required of it?

Any regular Sentosa beachgoer might notice that for several years, an extra peak bus shuttle operates to bring passengers direct from Beach Station to VivoCity, supplementing the monorail services. Queues outside the monorail station were also unfortunately quite common, and considering that there were already queue lines on the platform level. Resorts World Sentosa has even had to resort to building queue lines outside the station.

This means trouble (photo by me)

What does this tell us? Some pundits say that this means the monorail needs a third car or some other form of system expansion. Will that happen? There’s a good case for it. In the 2018/19 financial year, the island had 19.7 million visitors — which works out to about 54 thousand a day on average. Put this into perspective that weekends generally tend to see more passengers than on weekdays. Early proposals for a people mover to Sentosa, in fact, called for a system capable of hitting 5000 passengers per direction per hour.

In comparison, the current monorail claims to have a theoretical maximum passenger capacity of 4000 passengers per direction per hour. With the installation of the CBTC system in 2017, we might already be there, and this means only a small percentage (around 20%, maybe?) of daily visitors can use the monorail. High entry fees when entering by monorail (before the free entry promotion) also put people off that way, but since you can exit the monorail for free, many people tend to do that.

All these are conjecture based on provided numbers — I can’t find any breakdown of mode share on how people access Sentosa. But at least based on the existence of the additional buses in the evening, it points to the monorail being beyond capacity for how people use it.

System optimization

There seem to be some low hanging fruits that can be done to achieve a more efficient operation. Some of these do require infrastructural changes, but are likely to be less disruptive compared to the Hitachi engineers’ recommendations to build a second track like MRT terminals — rare in a monorail.

The first thing we look at is platform operations. There are queue lines and ushers at peak hours, giving it more of an amusement ride sort of feel. All alighting passengers must be clear of the platform before the ushers allow boarding passengers in the queue lines to join the train. This is sort of understandable due to the relatively narrow platforms and high passenger exchange, compared to quieter LRT stations.

One thing that could happen is to apply the Spanish solution, to speed up passenger alighting and boarding, by building a second platform face on the opposite side of the monorail track. That way, boarding passengers do not have to wait for alighting passengers to be clear of the platform before boarding the train. Basically, this is similar to what is happening at Choa Chu Kang LRT station or even at the VivoCity monorail terminal.

For starters, the additional platform face would be useful at Beach station, since it functions both as a terminal and as a transfer hub to the buses for Siloso Point and other places. Beach shuttles stop there as well, which means Beach station may thus see some of the highest amount of passenger exchange. There seems to be some kind of construction near the old taxi bay, so who knows, this might already be happening.

photo: me

But there’s also no saying that it wouldn’t be useful at other stations as well. In any case, additional platforms can be constructed without impact to the service provided there is space around the stations, so there’s that to consider.

Secondly, improvements can also be made to micro-optimize the train control systems. There are two parts to this — the first is simply to consider raising speed limits, especially on the long clear stretch entering Sentosa Island itself. Spec sheets may say the trains run up to 50kph in service, but at least when I was there it didn’t go any much past 40kph. In comparison, the LRT lines with similar alignments are capable of hitting 55kph at least on long straight sections.

The second is to examine the interactions between platform doors and train doors — unlike on the MRT system, on the Sentosa Express the train doors will fully open or close before the platform doors operate. Doing something about this could allow system operations to be tightened to a point where passengers become the main issue — and it is here where separate boarding and alighting platforms help.

Car heavy

The next issue here comes from the designs of the trains themselves. Some could be fixed in a mid-life refurbishment, but for some other points, completely new trains might be required. While officially “small-type monorails” according to Hitachi, the Sentosa Express vehicles are actually larger than Hitachi’s original proposals for small-type monorails.

A 4-car small-type monorail, according to Hitachi’s original concepts, would be 2.5m wide and 37m long, capable of carrying 194 passengers. 2-car Sentosa Express vehicles, however, are 25m long and 2.7m wide — closer to the Sengkang-Punggol LRT. However, it has to be said that a 2-car LRT train, with space taken up by emergency exit doors and no walkway between cars, carries 200 passengers. A 2-car monorail train, with no middle cabs and walkways throughout the vehicle, was rated to carry only 184 passengers on opening day, lesser than the LRT, and it might be further reduced today considering the CBTC equipment cabinets take up quite a fair bit of space.

Biggus chungus (source: SGTrains)

I’d think this means space is being used much less efficiently on the monorail vehicles compared to even LRT vehicles. The first step could be to get rid of the cabs and perhaps to consolidate some of the equipment spaces into what used to be cab space, including driver facilities such as the cab door and pull-down window. If this is done during a mid-life upgrading, perhaps some equipment redesign can be made to integrate existing CBTC equipment into dead space currently on the cabs, much like the R151 train where the Thales SelTrac cabinet is no longer visible in the passenger cabin unlike older trains.

Train Captains on the monorail can then either act like rovers on our automated MRT lines and remain in the passenger cabin, with the capability to operate the train from the emergency control panel as necessary. Some of them already do this instead of remaining inside the cab, though it appears to be a matter of staff personal preference. Or their presence can be completely dealt away with, but this may open another can of worms considering how a stranded monorail vehicle would have to be accessed.

Three’s not necessarily a crowd

The second factor gets quite clear once the very sharply angled aerodynamic ends of the monorail vehicles are examined. Whilst original proposals made by Hitachi called for 10m long end cars on the small-type monorail (including a cab), the Sentosa Express has 12.5m long cars. The additional length of the vehicle is likely due to the aerodynamic ends, which can potentially be used for a certain amount of equipment space and not much more. Consequently, almost a quarter of vehicle length is reserved just for the cabs, resulting in smaller space for passengers.

A more disruptive approach would be to replace the existing fleet with trains that are of similar length to the existing two-car trains, with no cab and no aerodynamic cab ends, thus using more of the available vehicle floor area. These could be more akin to the Okinawa Monorail, perhaps with modifications to meet the maximum length possible on Sentosa. However, incompatible door spacing may result in the platform doors having to be replaced as well, as it makes little sense to keep the current two small doors with a larger train carrying more people. Adding doors might also help to reduce dwell times.

Okinawa Monorail (source: 663highland on Wikimedia Commons)

Or they could persist with the small-type monorail design, but with each end car being shorter due to the lack of aerodynamic cab ends and separate driver spaces, use the space to insert a third car. This may solve the issue mentioned above with platform door spacing. Essentially, this means getting something like this, which may fit inside the 25m available length:

figure amended from Hitachi’s paper

But why go so far, instead of just adding a third car into the middle of the existing monorail vehicle? Bluntly speaking, it is difficult to expand the monorail depot, so probably purchasing new trains is the cheaper, more convenient option. The depot buildings are 45-60m long, at least in the covered area, based on Google Maps measurements. While after factoring in things like staff facilities, walking space, and space for buffer stops, this may mean one could store longer trains in the depot, it may not be that easy.

The pale yellow beams at each end appear to be some form of traversers which allow the monorail trains to move across the depot to the various service tracks. The whole monorail train must be able to stop within the traverser in order for the traverser to move, similar to how a lift must stop with doors aligned at the same level. Longer monorail trains would require this traverser to be extended as well, which could mean a rebuild — potentially pointing to the shutdown of the monorail for a while and having to build a larger depot.

screenshot from Google Maps

In short, while we can’t have longer trains despite what certain people may say, we can look at making the most out of our existing trains by thinking about how we use the space inside them.

Why bother?

Why do all this? After all, there’s a much easier option — to construct a new monorail line perhaps connecting to the Greater Southern Waterfront and CCL6 somewhere. Passengers to Sentosa can then be split between the current Sentosa Express and the new monorail — but without a fare cut, since HarbourFront has two MRT lines compared to only one along CCL6, it may not work as well.

But considering how much of a great unknown the SDC’s Sentosa-Brani Masterplan has been so far, at least to the public, we don’t know when this will happen. It is thus timely to also consider any potential optimizations that can be done to the monorail system in the short to medium term to increase its capacity, while long-term actions are taken.

Of course, there are other options, so it may not appear so critical to improve the monorail service. It was free to use the Sentosa Boardwalk to enter Sentosa on foot for a very long time — at least until the current free entry promotions. There are also the buses, which Sentosa also have plans to electrify. They could simply run more buses, assuming the manpower can be found.

But to me, that doesn’t mean steps should not be considered to optimize the monorail operations, especially if Sentosa wishes to expand its operations and increase its visitorship. Or, I guess, they could just find a way to introduce autonomous shuttles not only in the island, but also out to VivoCity’s pick up point.



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