NETIZEN: MRT BREAKDOWNS ARE NOT ALL SMRT’S FAULT, SIGNAL TESTING IS TRICKY & HARD

I try to minimize my complaints about our rail transit system because I personally think it is much maligned. That said, the recent spate of disruptions has been bad. And the announcement that it will take 4-6 months to iron out the kinks is testing even my patience. I’ve been caught in the congestion the last 2 days. What is going on, and is SMRT deserving of all the brickbats it’s getting? I think it’s not all their fault.

First off, having taken public transport overseas, I think Singaporeans are quite spoiled when it comes to our commuter rail. It is relatively cheap and the wait times are tolerable. And there’s 4G in the tunnels. I think the problem is that people are comparing it to what they remembered in the 1990s and early 2000s, when seats were abundant and delays were rare. So what happened? 4 main factors, I think, have contributed to the underlying problem (signaling fiasco aside): increasing ridership, ageing infrastructure, poor urban planning and incompatible immigration policies and insufficient maintenance. Only the last one is SMRT’s fault.

1. Ridership is a huge factor. Another subway line facing similar issues is the NYC subway. The system is aging badly, as it is 120 years old in some places. But the main problem is the relentless increase in ridership, for very little increase in network length. This causes compounding problems because more riders increases the loading times at stations, which causes knock-on ripple delays. The system was designed for 30 seconds at each station, but the more the passengers, the longer they take at each station, resulting in more congestion. In ops management this is called a queueing problem. Unfortunately the only solution is to increase the number of trains or lines, both of which have long lead times. Read more here: https://nyti.ms/2uhnd4h

The increased ridership isn’t SMRT’s fault. If anything, it is the govt which may have underestimated the ridership growth or otherwise didn’t fully account for it when planning immigration policy. Our trunk lines (NSEW) were not designed with the current ridership figures in mind. They were designed more than a decade before our govt embarked on its massive immigration policy.

2. Aging equipment. Our SMRT uses a mix of rolling stock, with the latest new build C151A models being less than 3 years old, and some of the original Kawasaki C151s in service since 1987 still running. The design lifespan for such trains is about 40 years, which means that the C151s are nearing the end of the so-called bathtub curve. Basically, after the initial infant mortality phase, equipment will enjoy a long period of low malfunctions, before gradually increasing at an increasing rate until retirement. Likewise for the signaling systems and the electrical relays in the original track sections.

3. Also, urban planning and immigration policy (which SMRT has no control over) have a huge impact on rail congestion. The addition of hundreds of thousands of sq ft of office space in the downtown area, without a commensurate increase in rail network there, has no doubt contributed to the congestion. I think, for example, that the Marina Bay Area should have been developed as a recreational space rather than a bigger CBD. A satellite CBD should’ve instead been set up, like Canary Wharf in London. Changi Business Park is a step in the right direction.

4. Finally, what I think is SMRT’s fault: I think during the Saw Phaik Wah years, they (reportedly) scrimped on maintenance in favour of aggressive retail (and hence revenue) expansion. The amount they spent on maintenance as a % of revenues was significantly below what HK’s MTR spends. This was a mistake. Like how brushing teeth daily keeps cavities away, routine maintenance isn’t something that should be scrimped on. By the time you have gum disease and cavities, the options you have are costly and may not leave you as good as before.

So, that’s the underlying problem. What about the testing, which has unleashed this round of chaos?

“What are they testing?” Some of my friends believe they are covering up track faults under the guise of testing. But if you follow the news, SMRT is rolling out communications based train control (CBTC) systems to replace the fixed block system in 2017. The original system breaks the track into fixed 500m blocks, with a minimum separation of 1 empty block between trains. This means that to maintain a separation between trains (“headway”) of 500m, you get gaps of up to 1000m. With CBTC, each train constantly tells the system where it is, and a constant 500m gap can be maintained. This will allow trains to run closer during peak periods, giving a modest but noticeable frequency boost especially during the peak periods.

“Should they be testing it live now? Clearly it’s not ready!” Actually, the system was tested during the off peak periods starting in March this year. But at some point, live testing has to happen. Dynamic commuter loads and passenger flows are chaotic and sensitive systems that defy accurate simulation. The only way to verify it is to test it live. There may also be timing factors outside of SMRT’s control that come from LTA or transport ministry side.

“Why didn’t we see this problem with other lines when they started out? What’s gone wrong now?” In engineering, there is a difference between clean sheet designs (“greenfield”) and retrofits (“brownfield”) designs. Brownfield designs are trickier because there are interactions with legacy infrastructure that may be obsolete or incompatible.

In conclusion, I believe Desmond is no fool. SMRT’s maintenance spend has increased since SPW’s era (although I haven’t checked the most recent figures against MTR’s). Things feel like they’re deteriorating, but as outlined above, some of the factors are beyond SMRT’s control. And they are trying. Ultimately I think it’s going to get worse before it gets better. By all means, grumble. It is our god given right to grumble! But we should hopefully do so with a better understanding of the underlying causes. If you’ve made it this far, sorry for wall of text! I got kinda carried away adding more and more points from stuff I’d read up about in the past.

Disclaimer: I’m no expert in public transit systems, but this is what I’ve gathered from what I’ve read.

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