for those interested in the design, technology, planning, maintenance and operation of railways.
A new metro system opened recently in Bangkok, Thailand called "Skytrain". This page describes the background, the design features and the operation, following recent visits.
This page first completed 26 March 2000 and updated 8 April 2002.
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Background - Bangkok Metro Map - BTS Skytrain Map - The Skytrain System - Finance and Ridership - Construction - Siam - Stations - Trains - Rolling Stock Data - Operations - Design Capacity - Automatic Reversing - Maintenance - More Information (Links).
Bangkok
is the capital city of Thailand and has a population of over 10 million. It has a
reputation for having some of the worst traffic jams in the world - a problem only reduced
in recent times by the collapse of the Asian economies following the devaluation of the
Thai Baht in July 1997. The reduction in economic activity has reduced the traffic
to more sensible levels but the recent recovery in Thailand is already starting to show in
increased traffic congestion in the capital.
Rail has figured strongly in the City's plans to improve public transport and three schemes have been started to provide metro lines covering a number of main corridors in the central area of the city. These three systems have been proposed by the Bangkok Metropolitan Administration (BMA) but they have been started by different organisations. However, there has been some attempt to form a network and to eliminate duplication of routes.
The three systems are known as the Hopewell system, the MRTA underground system and the BTS Skytrain. The lines are shown on this MAP of Bangkok Metro Systems. The Hopewell system was started in 1996 but abandoned when the finances of the Hopewell construction organisation collapsed. The resulting concrete structures stand as silent monuments along the road from the international airport and at various other sites in the city.
The MRTA (Mass Rapid Transit Authority) of Bangkok has started work on a 20 km long underground line in the city running between Hualamphong main line railway terminal and Bang Sue in the north of the city. The civil works construction has been divided into two separate contracts, for the northern and southern parts of the line, and work is now proceeding slowly on both. The electrical and mechanical systems supply and the operating and maintenance contracts have been offered in a 25 year concession but, although a number of offers have appeared from time to time, no award has yet been made. The financial difficulties of the region and the doubts about the returns possible from the concession have made the award process slow and difficult. Negotiations have been going on for two years.
The Skytrain is the only system to have been built and opened. It is shown on this Map of the Skytrain system. It is run by a consortium known as the Bangkok Transit System (BTS) who have a 30 year concession to build and operate the two lines. The term Skytrain is the marketing symbol of the system, which gets its name from its all elevated construction. Siemens, supplying electrical and mechanical equipment and Ital-Thai (civil engineering) are the two main engineering companies behind the project. The line was opened on the Thai King's 72nd birthday, 5th December 1999.
The BTS Skytrain consists of two metro lines, built on concrete elevated viaducts along three major corridors in the central part of the city. The two lines cross at the Siam centre, a major shopping area near the World Trade Centre and the National Stadium. Siam station is built for easy, cross platform interchange between the two lines. The lines are known as the Sukumvit line and the Silom line from the names of the principal streets they follow. The Sukumvit line runs from the eastern terminus at On Nut (pronounced Or Nood) via Siam ( pronounced See Am) to Mor Chit near the northern bus terminal. The Silom line runs from Sathorn Taksin at the river via Siam to the National Stadium.
The cost of building the system was USD 1,800 million or GBP 1,100 million. This is USD 78 million per km. It is interesting to compare this cost with that of the Manila Line 3 system, which opened at the same time. The Manila line cost USD 41 million/ km. This difference in cost can be seen in the quality of the civil engineering and equipment of the systems.
Finance for the BTS system was provided by the German export credit bank KfW (USD 600 million), various local banks consortia (USD 1,100 million) and the International Finance Corporation (World Bank), who supplied about USD 100 million. There was a considerable increase in costs over the original project estimates due to the currency problems of 1997 but the project has survived following some financial restructuring.
The original project plan offered a projection of 680,000 passenger journeys per day. If calculated at 330 days per year and an average fare of 25 Baht, this provides an annual income of USD 140.25 million. The rate of return for investors is given as 16%. The present traffic is running at about 105,000 per day and will probably only just cover operating expenses.
The reason for the low ridership is the cost of fares. Fares are graduated between 10 and 40 Baht. Bus fares are one third this level and bus routes parallel both lines. It is common to see packed buses struggling along Sukumvit Road in the traffic while the trains run overhead virtually empty. However, there is bound to be an improvement as the system gets better known and as travel increases with the recovery of the economy. All new systems pass through a slow start-up curve, which can last for several years.
The daily usage pattern is unusual. The morning use of the system is very low. Even during the traditional morning peak periods, trains are only carrying seated passengers with very few standing. This changes towards lunch time when traffic builds up rapidly and remains at a reasonable level until mid evening, when it falls again. Most riders are young people. Older people I have seen on the trains seem bewildered and amazed by the whole experience.
Of course, the high fare is needed to provide the income to support the commercially designed financial structure of the project. This is inevitable is a privately funded railway like this, since the money market dictates that the cost of the enterprise has to be paid for out of income. There is some hope that property development will assist with the financing but this is a long term prospect, particularly in the current economic climate. It remains to be seen as to how the shortfall in patronage and income will be handled. Some form of government intervention seems inevitable.
The whole route is built on elevated post-tensioned concrete viaducts supported along street centres by concrete columns. To see a cross section drawing of the viaduct, click here. The spans were made up of single cell units pre-formed off site and then lifted into position on an extended steel truss. Tensioning was carried out using internal cables. The standard viaduct is 9.9 m. wide. The standard spans vary in length from 27 metres (88 feet) to 38 m. (125 feet) between columns but the longest span is 60 m. (197 feet). Most of the columns are 12 m. high (40 feet) but some of the foundations have been sunk to a depth of 55 m. (180 feet) because of the poor ground conditions.
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 Viaduct from road level Click to enlarge and read description |
 Walkways at Phrom Phong Click to enlarge and read description |
Most of the routes are straight, following the lines of the streets below the viaducts but there are some very sharp curves at Siam and Victory Monument (see photos below). The sharpest radius is 87 metres (285 feet) on the main line and 80 m. (262 feet) in the depot. There is some flange noise on these curves but it is possibly due to check rail contact.
 The viaduct at Victory Monument Click to enlarge and read description |
 Curves on the viaduct at Victory Monument Click to enlarge and read description |
The stations are built with the tracks at a higher level than on the intermediate viaducts. This gives the line a "hump" profile, with the ramp up to each station assisting with train braking and the exit ramp down assisting with acceleration. Track is at standard 1435 mm (4 ft. 8½in.) gauge, fixed directly to concrete plinths on the guideway. There are also concrete upstands outside the rails to confine derailments. Traction current at 750 volts DC is transmitted to trains via an under-contact third rail, composed of aluminium with a steel contact surface. There are 10 traction substations on the system supplied through two bulk feeder stations at 25 kV AC. Each passenger station also has its own substation for local power supplies.
At Siam station, also called Central Station and where the two lines of the BTS system meet, a cross platform interchange arrangement has been built, involving the provision of two levels for platforms and tracks and the associated ramps for the routes into and out of the station. Each line, originally with both tracks at the same level, enters the platform area with one track above the other opposite the corresponding track of the other line. As the tracks leave the platform area, they begin a gradual return to the same level.
The different levels of Siam station are connected by stairs and escalators. There is a high level of interchange between trains on the same level and some between the two levels. The whole Siam structure is squeezed between the shopping centres on either side of Sukumvit road, with only about two metres clearance in some places. This also occurs at some of the other stations on the system. At some, the platform is level with roof gardens of apartments. One wonders how the residents feel about having a full-sized train set in their back gardens.
 Western side of Siam station Click to enlarge and read description |
 Lower level platform at Siam Click to enlarge and read description |
 Upper level platform at Siam Click to enlarge and read description |
All stations are built to a common design theme. Platforms are 150 m long and can accommodate a 6-car train. At present, only 3-car trains are being operated. Stairs from street level (see photo below) give access to a mezzanine where ticket offices and ticket machines are located. The mezzanine is also provided with a station control room and spaces for various concessions, some of which are already occupied.
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 Faregates and ticket office layout Click to enlarge and read description |
Ticket and change giving Click to enlarge and read description |
At many stations, a network of elevated footpaths and bridges connect with the mezzanine (see photo above) to give access to local adjoining streets. The mezzanine level leads to the ticket office, automatic ticket vending machines and the automatic faregates. The ticketing system uses plastic stored value tickets and these are offered for single journeys as well as stored value cards of up to 500 Baht. The TVMs sell only single journey tickets and only accept coins. Because of the demand for change, each ticket hall area has a table set out where young ladies are employed (see photo above) to provide change during the busier periods of the day. This appears to be a temporary arrangement.
Access from the mezzanine to the platforms is either by more stairs or escalators. Escalators are not provided in all locations but the standard design has one rising to each platform. Exit down is via stairs. Escalators are designed to transit standards, with a four-step flat portion.
At platform level, there is a uniform design approach. While the design is pleasing to look at, the sameness at every station leads to a feeling of boredom and dullness. A split station roof design has been adopted, with a central opening for ventilation purposes. The canopy over each platform is also mounted on two levels, with an intermediate gap to aid air circulation in the tropical temperatures. There is no forced ventilation or air conditioning on stations.
 Typical station at platform level Click to enlarge and read description |
 Passengers sheltering from the sun Click to enlarge and read description |
 Platform markings Click to enlarge and read description |
The tropical heat and severe rain conditions lead to special requirements for station designs. Not least is the importance of good drainage to carry away rain water and the need to extend platform canopies far enough to protect waiting passengers from driving rain and the tropical sun. In the case of protection from sunlight, there are some problems as can be seen in the centre photo above, where passengers are forced to gather in a small area of shade to protect themselves from the direct sunlight. It is also interesting to see the handrails of all stairs and barriers are in unpainted stainless steel. This becomes very hot in direct sunlight and needs some sort of protection to allow it to be touched under these conditions.
 Stairway with exposed steel handrails Click to enlarge and read description |
 Stairway with clear slots Click to enlarge and read description |
During the construction phase, there was some criticism in the Bangkok press about the lack of lifts at stations for the disabled. Only five stations are equipped with lifts. This was an afterthought, only included in the construction after a public protest.
The BTS system has been provided with an initial fleet of 35 x 3-car trains supplied by Siemens out of the SGP factory in Wien (Vienna), Austria. Train lengths can be increased to 6-car trains in the future. A 3-car set is 65 m. long and comprises two driving motor cars (A cars) with traction equipment with a trailer car (the C car) between them. When extended to 6 cars, two non-driving, motored cars (B cars) and another C car will be added.
The car body is constructed of spot welded stainless steel and is similar in design to the cars supplied for the Taipei (Taiwan) metro system. The body shell exterior is painted in two layers of epoxy primer and two finishing coats of acrylic, graffiti resistant paint. The cab ends are in Glass fibre Re-inforced Plastic (GRP). The floor is built to a 45 minute fire resistance specification and is covered in hard wearing PVC with a blue or grey speckled pattern to reduce dirt visibility. Car windows are tinted to reduce glare.
 Bangkok BTS trains Click to enlarge and read description |
 Cab end of train Click to enlarge and read description |
Wide end gangways are provided within each unit to assist in the circulation of passengers. All seating is longitudinal and there is a large amount of available standing space. I never saw it all used. Seats are in yellow GRP and are arranged in concave curved sets. At first I assumed this was to accommodate door engines fitted on the floor behind the seats but the door operators are mounted in the ceiling. They are exposed to view from the outside of the train when the doors are open. I wonder if this will lead to maintenance problems in the future. I cannot see any reason for the curvature of the seats.
The interior panels are of GRP finish in a special graffiti resistant paint. Of course, there is no graffiti on public transport in Thailand and very little anywhere else in the country.
 Car interior Click to enlarge and read description |
 Gangway panels Click to enlarge and read description |
 Curved seating group Click to enlarge and read description |
 Open doorway Click to enlarge and read description |
Each car has four sets of bi-parting doorways, externally mounted. Electric door operators have a threaded rotating shaft drive and these are mounted over the doorways. The glazing in the doors is in an unusual design, presumably to reflect the direction of closing. Porsche Design was employed to assist in the system design. The train control system has a door lock which activates with a loud "click" as the train starts. I also noticed an emergency door opening device on each car. This, I was told, is activated by the driver in case of an emergency so that passengers can escape. As there is no side walkway and only a low barrier along the outsides of the viaduct, I thought this to be a somewhat unsafe practice. There is nothing to stop a person opening the door and falling 12 m. into the street below. There is apparently, some internal debate as to how this should be used. End evacuation is the preferred option for emergencies as trains are provided with end doors in the cabs and the centre of each track is reserved as a walkway.
 Cab desk Click to enlarge and read description |
 Car exterior connecting bellows Click to enlarge and read description |
 Interior door opening device Click to enlarge and read description |
A noticeable feature of train operation is the forward and aft rocking which occurs when the train stops. This must be due to the suspension. However, the ride is generally very good. There is a certain high level of low frequency noise which seems to come from the air conditioning pods mounted in the roof at each end of the cars. This noise can be quite unpleasant at times. There is also a high frequency tone from the traction/braking units, which appears to be electronically generated.
The traction equipment is Siemens IGBT 3-phase system driving 2 traction motors on each bogie. There are two converter units on each motor car, one supplying two motors. The maximum tractive effort per motor is 250 kW or 230 kW continuous with a maximum speed of 3,600 rpm. Air controlled friction braking and dynamic braking is provided on the motor cars with friction braking on the trailers cars. An automatic, spring applied parking brake is also fitted. Friction braking is through wheel mounted discs. The control system provides for dynamic braking at all times, with friction braking added on the trailer car if required. Full emergency capability is provided in the friction brake system. The wheel slip control has speed sensors on all axles.
| Item | Data | Comment |
| Train - overall length | 65,100 mm | 3 -cars over coupler faces. |
| A Car - overall length | 21,800 mm | over coupler faces. |
| A Car - body length | 21,280 mm | |
| C Car - overall length | 21,500 mm | over coupler faces. |
| C Car - body length | 20,760 mm | |
| Distance between coupled bodies | 740 mm | |
| Width overall | 3,120 mm | |
| Width over body shell | 3,000 mm | |
| Interior width | 2,800 mm | |
| Interior gangway width | 1,400 mm | |
| Floor height above rail | 1,160 mm | |
| Height above rail | 3,860 mm | |
| Doorway clear opening | 1,400 mm | |
| Bogie centres | 14,800 mm | all cars |
| Bogie wheelbase | 2,300 mm | |
| Passenger seats per car | 42 | |
| Passenger capacity (crush load) | 1,100 | at 8 persons/m2 |
| Max. tare weight of 3-car set | 105.6 tonnes | |
| Max. axle load | 14 tonnes | |
| Interior noise levels at 80 km/h | 74 dB(A) | |
| Exterior noise level at 80 km/h | 80 dB(A) | at 15 m distance |
| Traction motors rating | 250 kW | one hour |
| Traction motors rating | 230 kW | continuous |
| Motors per train | 8 | 2/3 axles motored |
| Max. motor speed | 3,600 rpm | |
| Gear ratio | 6.368:1 | |
| Wheel diameter | 850 mm new, 775 mm worn | |
| Acceleration (max.) | 1.25 m/s2 | |
| Deceleration (service brake) | 1.34 m/s2 | |
| Deceleration (emergency) | 1.57 m/s2 |
The system operates a standard 5-minute headway throughout the day, which is reduced to 3 minutes during the morning and evening peak period. Services start at 06:00 and end at 24:00 hrs. Some 33 of the 35 trains are required for the peak service. All operations are controlled from a single control centre which has an operations desk and an engineering desk. Operations can be viewed on a large projected wall screen, which is of good quality resolution.
 Control centre operations desks Click to enlarge and read description |
 Control centre engineering desk Click to enlarge and read description |
Trains are operated under ATO. Trains are normally driven automatically and, after stopping in the platforms, doors are opened automatically. An operator is provided on the train to close the doors and make announcements. Announcements are not automatic. Trains can, and are, driven manually in service but this seems to be the exception rather than the rule. Doubtless this will change when boredom sets in for the train operators and when it is realised that some driving experience is required to keep up skill levels for emergency situations.
Platforms are provided with emergency buttons so that passengers can stop trains by operating the button and thus dropping the ATP codes. Platforms are also provided with mirrors to assist train operators when closing doors. Clocks are located on every platform and mezzanine and are consistently accurate.
 Track in station with loops Click to enlarge and read description |
 Emergency train stop button Click to enlarge and read description |
 Mirror and clock on platform Click to enlarge and read description |
The ATO function is overlaid on the ATP system which operates through coded track circuits. The signalling is controlled through five interlocking areas which supervise train running and detection with 285 jointless track circuits. ATO is controlled by transposed loops in station approach and platform areas. Stopping accuracy appears to be in the range ± 150 mm. Lineside signals are provided at switches and these show red or white indications only. Crossovers are provided at Siam to give access between the depot at Mor Chit on the Sukumvit Line and the Silom Line. There are emergency reversing crossovers on each of the three main branches and a reversing siding at Asok (pronounced Ah-So).
Dwell times are standardised at 25 seconds for all stations except Siam. At most stations, the 25 seconds is much more than is required for boarding and alighting. At Siam, cross platform interchange is provided and trains are timed to connect. Dwells at Siam are usually 60 seconds.
The administration offices, depot and control centre are located at Mor Chit. The depot site was constrained in various ways and access is only by reversing all trains through the headshunt at the northern end of Mor Chit station. The depot has only one entrance. The site also requires that trains can only pass through the automatic washing machine by reversing twice.
 Offices and Depot at Mor Chit Click to enlarge and read description |
 Trains reversing at Mor Chit Click to enlarge and read description |
 Stabling at Mor Chit Click to enlarge and read description |
There is some evidence of a growing intermodal traffic. Passengers go to the northern terminus at Mor Chit where there is interchange with buses for destinations further north. It is strange to me that the line did not continue north two more kilometres to the "Central" shopping mall and Bangkok convention centre area. However, taxis are now always available at the station exits on both sides of the street.
| Line | Train headway | Passengers/peak hour/direction |
| Sukumvit Line | 135 seconds | 22,500 |
| Silom Line | 225 seconds | 13,500 |
Automatic, driverless turnrounds are provided at terminals. Each terminal is designed with an arrival platform and a departure platform. The train moves from one to the other via a headshunt (turnback or reversing track) beyond the station. Each terminal has two of these tracks and either can be used. At Mor Chit and National Stadium, a train is stabled beyond the station on one of the headshunts during the off-peak periods.
 Trains reversing at National Stadium Click to enlarge and read description |
 Train reversing at Mor Chit Click to enlarge and read description |
From observation and as described to me (in various ways by various people, none of whom agreed with the others), the system appears to work as follows. When the train arrives, the train operator opens the doors, allows passengers to alight and then closes the doors. He will wait for a lineside signal (red/white) to show a white aspect to indicate clearance to start the reversing procedure. He can then initiate automatic turnround in one of two ways:
| Operator remains on the train | Operator stays off the train |
| 1. Remove control key from cab desk | 1. Depress in-cab automatic reversing button |
| 2. Alight from train and use key to activate platform reversing switch | 2. Remove control key from desk |
| 3. Board train, close cab door and insert key | 3. Alight from train and close cab door |
| 4. Depress in-cab automatic reversing button | 4. Use key to activate platform reversing switch. Train starts. |
| 5. Remove control key from desk. Train starts. | 5. Walk to other platform to meet train |
| 6. Walk through train to the cab at the other end and insert key | 6. Open cab door, board and insert control key. |
The train reverses without the operator being in the cab. The time taken from wheel start to wheel stop is exactly 90 seconds. The operator has enough time to walk to the other end cab before the train enters the platform. However, there is no rule which says he has to be in place during that movement.
The consortium headed by Siemens has given a 5-year contract to Siemens to maintain the system. This includes track, infrastructure, equipment and rolling stock maintenance. Cleaning is the responsibility of the operating company BTS. The maintenance contract is run through a computerised maintenance management system. About 190 staff are employed for maintenance, including administration.
The only equipment not being maintained by the Siemens organisation is lifts and escalators. This is outsourced and, I was told, the contractors are closely supervised to ensure that the work is carried out properly.
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Bangkok Skytrain Website (unofficial): For more information about the background to the Bangkok Skytrain system and photos of the line, try this excellent site. There are also translations of various local newspaper articles concerning the system. |
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Bangkok BTS Website - The official Skytrain site. |
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Bangkok Map - A map of Bangkok showing the metro routes and their relationship with local streets. |
Sources: Tramways & Urban Transit; International Railway Journal; Railway Gazette International; "The 3-car units for the Bangkok Mass Transit System", Hans-Joachim Fischer, Rail Solutions Asia 2000, Bangkok, 17 March 2000; "Maintenance for the BTS Project", Walter Gintschel, Rail Solutions Asia 2000, Bangkok, 17 March 2000.
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This page first completed 26 March 2000 and updated 8 April 2002.
