Structure and Stations

The general viaduct structure of the project must be aesthetic and accommodate 2-direction guideway beams running along the line. The line is to be placed on road medians as much as possible to minimize impact to the public and avoid the need to expropriate land. Construction should be simplified and swift to reduce traffic congestion issues.

1. Superstructure - Consultants reevaluated the original study and set the length and size of beams and a continual beam design using beams 25 m. in length with 5 beams connected (5x25=125 m.) and beams 29 m. in length with 5 beams connected (5x29=145 m.) to reduce the amount of foundation posts, bases, piles and bearings. Prefabricated beams prepared for assembly on site were chosen to expedite construction and for better quality control.

In scenarios in which the general designs are not applicable, consultants designed a 2 to 5 section support structure utilizing beams 25, 29 and 35 m. in length.

For road intersections requiring longer than usual distances, a 40-60-40 m. length design was chosen.

2. Substructure - Consultants reevaluated the original study and positioned pillars to support the line and avoid the need to move utilities. The consultants decided on using bored piles and barrette piles drilled into the second layer, a hard clay layer, to ensure their weight capacity and ability to withstand dangers. This reduced the number of piles in bases and the size of bases, improving resistance to subsidence and the possibility of cracks forming between bases and road surfaces. Pillars chosen for the project include single pillars for 2-direction guideway beams where placement on road medians is viable, single-center deviated pillars for 2-direction guideway beams, and single pillars for 1-direction guideway beams for Portal Frames where placement on road medians is not possible.

In cases where the road median is above a large sewage pipe that is over 2.00 m. from the surface, to avoid moving of the pipe to accommodate a pillar, the consultants designed a single pillar placed on a base with 2 piles able to straddle the pipe.

Monorail stations are designed with the features and space required for the operation of trains. Due to trains differing in dimensions depending on manufacturer, monorail stations must be able to accommodate different models by reducing or increasing certain dimensions. The entire line is elevated stations that range in height based on position and the limitations of each location. Stations were designed to feature aesthetic roofs and ceilings that, when viewed from below, provide adequate shade and protection from rain but do not obstruct natural light.

Three formats were chosen for stations to accommodate platform layouts, management of the rail system and the limitations of each location:

1. 2-Level Side Platform: Platforms are located on the two outer sides of the station alongside two attached rail lines. A passenger area is provided in the center of the station. Beneath the platforms are two levels.
2. 3-Level Side Platform: Platforms are located on the two outer sides of the station alongside two attached rail lines. A passenger area is provided in the center of the station. Beneath the platforms are three levels, including a multi-purpose level at the bottom-most level.
3. Center Platform: The platform is located in the center space of the station with rails running on either side of the passenger area. Underneath the platform are two levels. Stations were designed with architectural unity as well as for structural integrity and safety, longevity, ease of maintenance and with adherence to international standards.

The majority of the line’s stations are elevated structures positioned in the center of roadways. Station pillars are spaced 25.00 – 27.50 meters apart depending on appropriacy for each station.

Prefabricated I and U girders were used for beams and cast on site. Entry and exit ways are located to the sides of stations. Each side of the station is a reinforced concrete structure with pillars 6.00 – 10.00 meters a part depending on the allowance of the location. Bored piles are used for station foundations to minimize impact on the surrounding area.

The Maintenance Depot is located at the juncture of Srinagarindra Road and Bang Na-Trat Road near the Park & Ride Building and Si Iam Station.

The design concept for the depot focused on natural light and ventilation due to its large and spacious size. Air ventilation and natural light entry is carried out through the depot’s roof. Functional spaces, such as spare parts storage and offices, are limited to a single side of the structure. Ventilation in the administrative office was optimized to reduce the need for air conditioning to a minimum, especially in halls and rooms apart from offices with the structure positioned for optimal airflow. Safety was a consideration of the Operation Control Center and access was restricted. A cafeteria able to accommodate up to 100 staff was provided as a separate structure to the depot to minimize issues to do with cleanliness.

The Park & Ride building is an integral part of the electric train system as it is where passengers may transfer from their personal vehicles to electric trains to journey into the inner city. The main focus of the building’s design was to accommodate a free flow of traffic and to clearly separate roadways and walkways in the interest of safety. Automobiles travel one-way in the split-level structure with ramps provided where appropriate to facilitate the swift outflow of cars during peak times. Staircases and bathrooms are provided approximately every 60 meters, where fire hose boxes are also installed. At least 50 percent of the building’s exterior walls are channels for ventilation.