Transportation Deployment Casebook/Singapore MRT

Figure 1: Pagoda Street entrance to Chinatown MRT. Note the elevated entrance to protect against floods

Introduction

The Mass Rapid Transit (MRT) is a mass transit system in the Republic of Singapore. Conceived in the 1960s, and built in the 1980s, the MRT system now stretches to all corners of Singapore. The MRT system features a lot of innovative technology, and is projected to grow further in the coming decades.

Qualitative

Technology

Figure 2: LED map display inside of a North South Line train. Note how the display has been retrofitted to display an infill station (Canberra) and as a result there is no LED light for that station.

The Singapore MRT is a heavy-rail rapid transit system. It runs autonomous trains across six lines and has 140 stations. There are also 3 LRT systems to supplement the main MRT system. The trains run on standard gauge 1435mm track and use DC third rail or overhead wire electrification (depending on the line). Newer trains are fitted with electronic maps, as well as external information displays (see fig. 2).

The main advantage of this system is that it is fully grade separated. This means there are no level crossings to slow down the trains. This allows the trains to offer high frequency services, 2-3 minutes on-peak and 5-7 minutes off peak. It also has a higher capacity than comparable modes, such as buses.

The MRT features many innovative technologies, which have been borrowed my many transit authorities around the world. All 140 stations are fitted with platform-screen doors, and newer stations also double as bomb-shelters. Newer underground stations also have elevated entrances to stop water entering the station in the event of a flash flood (see fig. 1). Additionally, the system features many cross-platform transfers, including a double cross-platform transfer at City Hall and Raffles Place between the East West and North South Lines. This enables passengers to travel in either direction on the line they intend to transfer to simply by crossing over to the other side of the platform at one of those stations. All stations have numbered exits for convenience, and many stations have exits directly into adjacent buildings.

Singapore uses a station numbering system consisting of a two-letter line prefix, and an individual station number. For example, Toa Payoh on the North South line is numbered as NS19. Interchanges have multiple numbers, and there are a number of exceptions to the station numbering rule (e.g. Founders’ Memorial TE22A, Tanah Merah EW4/CG, Punggol NE17/PTC to name a few). Singapore also numbers the end of its lines to make it easier for passengers to find the right platform. For example, trains towards Punggol are numbered as 7 on the system map and on station signage.

The system uses electronic cards for payment. There are multiple types of fare cards in circulation, most notable being the EZ-Link and NETS flashpay cards. However, today passengers can tap on and off using credit and debit cards, including digital wallets, due to the new CEPAS standard.

The MRT uses technology from all around the world. The MRT uses many different types of trains from manufacturers including Kawasaki Heavy Industries, Siemens, CRRC, and Alstom. Signaling systems come from Alstom, Westinghouse, Siemens, and Thales. Westinghouse also produced a portion of the platform screen doors.

Birth of the MRT

In the 1960s, Singapore was a small island with a growing population. This led to high traffic congestion and inefficient journeys. Growing congestion on the bus network was also causing concern, and a solution was needed. A joint study by the United Nations Development Programme and the Singapore State and City Planning Department was conducted to forecast Singapore’s growth in the coming years.. The 1967 study found that Singapore’s population was expected to balloon to 3.4 Million by 1992, and that to cope with the increase, Singapore would need to restrict cars, improve roads, and build a mass transit system.. Support for the MRT was not universal. There was a push for a bus-only system. Back then, Singapore was not the rich metropolis we know today, and the lower cost of buses was very appealing. In 1972, the Singapore Mass Transit Study was done, which recommended the construction of a heavy rail network. In 1980, consultants from Harvard University were brought in for a second opinion. This study found that an all-bus system may work, as long as a system was put in place to restrict car usage. However, a government study was then done in 1981, which found that a bus only system would not be enough. Following on from this, the Singapore Government decided to begin construction in 1982.

Construction began in 1983 on what is now the North South and East West lines, and the first section opened in 1987, with an official opening in 1988 by Prime Minister Lee Kwan Yew.

Growth of the MRT

Following the initial success of the MRT system, growth followed over the next few decades. In 1996 the Woodlands extension was completed which brought the MRT to the north of Singapore. Up to this point, there had been a branch line extending from Jurong East up to Choa Chu Kang. With the Woodlands extension complete, this branch was now linked up to the rest of the North South Line. As a result, trains no longer branched off the East West Line at Jurong East, and instead ran along the North South Line through Woodlands before running along the old branch section and terminating at Jurong East, forming a loop around Singapore's Central Catchment Nature Reserve.

In 2003, the North East Line was opened, which connected the north-east of Singapore with the rest of the MRT network. This was Singapore's first entirely underground MRT line.

Up to this point, the MRT system was almost entirely radial, with all three lines heading towards the Downtown Core. To address this, the Circle Line was constructed, opening in 2006. This allowed passengers to travel between suburbs without having to go through the city, helping to reduce crowding in the busy Downtown Core. The construction of the circle line saw the MRT’s first serious accident in the Nicoll Highway tunnel collapse. The damage was so severe that the whole collapsed area was filled in, the tunnels realigned, and the station reconstructed on a new site.

While the MRT was expanding, three new LRT systems were also built. These systems consist of automated people movers running on rubber tyres which connect to existing MRT stations with the goal of allowing passengers living in dense residential districts to get closer to their homes by rail. Although they seemed futuristic at the time, these systems are widely seen as failures as they were very expensive, unreliable, uncomfortable to ride, hard for disabled people to access, and (accounting for the time it takes to get from the sidewalk to the platform) slower than a bus. The Bukit Panjang LRT in particular is seven times less reliable than the downtown line. This line also used to contain Ten Mile Junction LRT station which was closed in 2019, making it the first and only rail station in Singapore to close due to low patronage. Government officials later admitted that the Bukit Panjang LRT system was constructed hastily in order to improve their electoral prospects.

At the moment there are three new MRT lines under construction. The Thomson-East Coast Line aims to connect the Woodlands area to the Downtown Line at Sungei Bedok via a new corridor along Singapore’s east coast. Similarly, the Cross Island line will connect the eastern part of Singapore to Ang Mo Kio and Bright Hill MRT stations along a new northern axis. This line will also provide an alternative to the heavily congested Circle Line. Lastly, the Jurong Region Line aims to serve the Jurong region by connecting commuters with the existing Boon Lay, Jurong East and Choa Chu Kang stations. Additional infill stations and extensions to existing lines are also planned. The MRT also has a number of unopened stations and shell stations ready to spring to life when future demand emerges.

Singapore has had a long-standing policy of promoting public transport over private vehicles. Singapore was the first country to implement road pricing (ERP), and the construction of the MRT system has allowed Singapore to reduce its dependence on private vehicles. As a result, the MRT is now the main way to get around Singapore.

Despite the overwhelming success of the MRT, there are multiple MRT projects that were abandoned or never build, including the East West Line Tuas South extension, and the Punggol North LRT.

Maturity

As the MRT is still expanding, the system has not yet reached its maturity. However, the system will reach its peak eventually. Singapore is an island, which means (with limited exceptions) there can be no more urban sprawl. Any future new MRT lines beyond the ones currently planned will likely provide new routes through existing areas, rather than serving new areas. As the population of Singapore increases, so must its population density, which may mean more MRT lines in the future.

Government Policies

Initially, the biggest policy of the Singapore Government was the decision to fund the numerous transport studies, as well as fully financing the initial construction of the MRT system. This indicates strong and unwavering support from the government of the day. It is extremely common for large projects such as metro lines and freeways to be completed through Public Private-Partnerships (PPPs). This is a form of collaboration between a government and the private sector in which the private sector fully or partially funds infrastructure construction on behalf of the government, in return for extended revenue over the course of the contract. In the case of a train line, a private company would pay for the construction of the train line, and then that company would get to charge fares to customers to pay back their investment. This would normally last for many years, before the infrastructure is handed back to the government. The Singapore Government did not do this because they wanted to spur investor confidence in the country, and because they wanted to keep fares cheap. The average MRT fare is only S$0.85, and this is by design. By keeping fares low, the MRT remains a viable option for all Singaporeans, and provides a realistic alternative to driving.

One of the Singapore Government’s other long-standing policies regarding the MRT is the use of transit-oriented development (TOD). Singapore, being a small island with a big population, has the potential to be one of the most expensive real estate markets on the planet. However, housing remains accessible to most Singaporeans due to government policies designed to get Singaporeans into home ownership. In 2023, 77.8% of Singaporeans lived in public housing, known locally as HDBs after the government department that regulates them, the Housing and Development Board. All HDB units are leased out to citizens for 99 years. The main job of the HDB is to develop vacant plots of land into “new towns”, where residents can live, shop and play. These days, most HDB developments are located around MRT stations. This enables citizens who live in the HDB community to easily commute into the city, as well as reducing the need for Singaporeans to own cars. Building MRT stations increases the land value around them , which in turn leads to more businesses springing up and more economic activity. The Singapore Government’s current target is for 8 out of 10 households to be within 10 minutes of an MRT station by 2030.

Figure 3: An ERP gantry on Killiney Road, Singapore

Despite designing its public transport to be a viable alternative to driving, a minority of Singaporeans do choose to drive. For this reason, the Singapore Government has developed road pricing systems to persuade people to drive less and use the MRT more. Singapore was the first country in the world to implement road pricing. Vehicles were charged a fee to drive into the downtown area of Singapore (known as the restricted zone). In 1998, Singapore switched to Electronic Road Pricing (ERP). This system involves gantries mounted above busy roads which charge drivers who drive through them, via units inside the vehicles similar to toll transponders (see fig. 3). The ERP charges change depending on the time of day and the prevailing congestion levels. Additionally, there is a quota on the number of vehicles allowed on the roads, and citizens have to bid for a permit to drive a car. This carrot and stick approach of making driving expensive and transit cheap, has helped to drive Singapore’s MRT ridership up, and car ownership rate down. These three policies of lowering car use, increasing public transport use, and TOD have contributed to making Singapore a more sustainable city. However, the Government is investing in new roads as well, such as the North South Corridor and Changi North Corridor, which may blunt the effectiveness of this strategy.

Currently, all future MRT stations are planned to be underground. There may be a number of reasons for this. Most new stations are likely to be in areas that are already built up, and as such, there would be no room for stations above ground. Additionally, there is a trend around the world for elevated viaducts to be seen as ugly and noisy. The Land Transport Authority (LTA) has been retrofitting existing viaducts with noise walls for this reason, and it is estimated that the social benefit of this program has exceeded S$700 Million Lastly, newer MRT stations also double as bomb shelters, which requires underground stations.

The MRT rolling stock and associated infrastructure is owned by the LTA, the transit authority of Singapore. The MRT system itself is operated by two different companies. The East West, North South, Circle, and Thomson-East Coast Lines are operated by SMRT Corporation, while the North East and Downtown Lines are operated by SBS Transit.

Quantitative

The MRT is currently in the growth stage of its life cycle. It is a well established system, but still has a number of extensions planned and under construction. To estimate how long the MRT will be in the future, a three-factor logistic function can be used. In this case, the function will take the form:

S(t) = S_max/[1+exp(-b(t-t_i)] where:

• s(t) is the track length of the MRT system in Kilometres
• t is the year
• t_i is the year in which the MRT system reaches 50% of its final size
• S_max is the final length of the MRT
• b is a coefficient which needs to be estimated

Data

System length data from 2005 to 2021 was sourced from the LTA. Additionally, the system is expected to reach 360km by 2030, and 400km by 2040.The dataset was assembled using these figures.

Modelling

To make the model work, values are needed for S_max, b, and t_i. To estimate b and t_i, a linear regression can be used. A linear regression requires the dependent variable to be linear in nature, so instead of regressing the dependent variable itself, it can be transformed into a linear form, and then transformed back to arrive at a prediction. The regression will take the form:

Y=bX+c where Y=ln(Length/(S_max-Length))

ln(Length/(S_max-Length)) is a linear transformation of the logistic function. The b term from this regression is equal to the b term in the logistic function. This regression also gives a value for t_i in the form t_i=c/-b where c is the constant term in the regression. In this case, t_i represents the midpoint of the regression line. As S_max has not yet been estimated yet, a test value of 500km will be used.

Year	System length	ln(Year/(500-Year)) (Y value)
2005	138.2	-0.962389662
2006	138.2	-0.962389662
2007	138.2	-0.962389662
2008	138.2	-0.962389662
2009	147.7	-0.869299896
2010	158.7	-0.765746228
2011	175.3	-0.616402887
2012	177.7	-0.595386054
2013	182	-0.558044696
2014	183	-0.549415621
2015	199.6	-0.408799556
2016	199.6	-0.408799556
2017	228.1	-0.175650222
2018	228.1	-0.175650222
2019	228.1	-0.175650222
2020	232.3	-0.141837311
2021	245.3	-0.037604431
2030	360	0.944461609
2040	400	1.386294361

Regressing Y on the year value returned the following results:

• b = 0.072345064
• c = -146.1664168
• t_i = c/-b = 2020.406225
• r² = 0.978846792

From here, the Y values can be transformed into predictions using the formula:

Predicted Length = S_max/(1+EXP(-b*(Year-t__i)))

Year	System length	Predicted length
2005	138.2	123.5104691
2006	138.2	130.3610072
2007	138.2	137.4527897
2008	138.2	144.7792635
2009	147.7	152.3321682
2010	158.7	160.1015059
2011	175.3	168.075535
2012	177.7	176.2407903
2013	182	184.582131
2014	183	193.0828173
2015	199.6	201.7246166
2016	199.6	210.4879371
2017	228.1	219.3519895
2018	228.1	228.2949721
2019	228.1	237.294278
2020	232.3	246.3267188
2021	245.3	255.3687619
2030	360	333.4349946
2040	400	402.4741113

The last step is to estimate S_max. To do this, excel solver can be used. The actual length can be subtracted from the predicted length for each year. These values can then be squared to calculate the sum of squared errors (SSE). Excel solver can then be set to minimise the SSE by changing the S_max value. Changing the S_max value will change the Y values, and therefore the regression results. However, the whole model was linked using formulas such as =SLOPE, =INTERCEPT, and =LINEST, so the regression results will refresh and still be accurate. The final model is shown below and in fig. 4:

Figure 4: Predicted MRT System Length over time

Year	System length	Predicted length
2005	138.2	125.9795829
2006	138.2	132.4898278
2007	138.2	139.2227959
2008	138.2	146.1745573
2009	147.7	153.3399304
2010	158.7	160.712444
2011	175.3	168.2843112
2012	177.7	176.0464201
2013	182	183.988339
2014	183	192.09834
2015	199.6	200.3634404
2016	199.6	208.7694628
2017	228.1	217.3011134
2018	228.1	225.9420785
2019	228.1	234.6751383
2020	232.3	243.4822954
2021	245.3	252.3449184
2022		261.2438953
2023		270.1597974
2024		279.0730472
2025		287.9640907
2026		296.8135684
2027		305.6024827
2028		314.312359
2029		322.9253968
2030	360	331.4246095
2031		339.7939489
2032		348.0184147
2033		356.0841459
2034		363.9784942
2035		371.6900796
2036		379.2088258
2037		386.5259798
2038		393.6341125
2039		400.5271049
2040	400	407.2001186

The final coefficients were:

• S_max = 537.9055032
• b = 0.066316646
• c = -134.1495991
• t_i = 2022.86465
• r² = 0.981442958
• SSE = 1713.366747

Interpretation

This system length column does contain missing values, but the linear regression will still function. It should be noted that this data represents the total length of the Singapore rail network (both the MRT and LRT systems). However, as no new LRT lines have been constructed during this timeframe, and there are no plans to construct any new ones, they will not affect the accuracy of the model. The total length of the LRT system accounts for 28.8km of the system length. The data does not seem to account for the closure of Ten Mile Junction Station, which means that this data also includes tracks used to access depots, since Ten Mile Junction Station is also home to the Bukit Panjang LRT Depot which remains in use.

This model predicts that the MRT will top out at 538km, and that the inflexion year was 2022. The R² for this model is over 98%. However, this does not mean that the model is 98% accurate. Rather, it simply means that 98% of the change in system length can be attributed to the passage of time.

The birth phase of the MRT was in the period 1987-1990, as this is when the first phase of the MRT opened. This birth phase proved the viability of the system and led into the growth phase, which continues until today. Based on the model, the growth phase seems to end around 2050. If the model is correct, by that point most the system will be constructed, and there will be very little left to build. The model predicts that by 2100, the system will be fully complete.