The parallel bridge to Rama 9 Bridge is a cable-stayed bridge that stretches across the Chao Phraya River in Bangkok, Thailand. It runs alongside the Bangkok Outer Ring Road (Phra Ram 3 – Dao Khanong – Western Outer Ring Road). This bridge, managed by the Department of Highways, is the first in Thailand to have dual pylons. It runs parallel to the Rama 9 Bridge and boasts 8 traffic lanes, spanning approximately 42 meters in width. Construction began on January 16, 2020, and was completed on March 30, 2023. The bridge is expected to open in March 2024, after the construction of the Thon Buri approach ramps. It is estimated that the bridge will be able to accommodate up to 150,000 cars daily.

The overall characteristics of the bridge

The parallel bridge to Rama 9 Bridge is a unique cable-stayed bridge, being the first of its kind in Thailand. It runs alongside Rama 9 Bridge and features 8 traffic lanes, with 4 lanes dedicated to inbound traffic and 4 for outbound traffic. With a width of around 42 meters, it holds the distinction of being the widest river-crossing bridge in Thailand. The bridge starts at the second level, approximately 10 meters above ground level, offering convenient access and reducing congestion during bridge ascent—a common issue with Rama 9 Bridge. It stands at a height of 41 meters above sea level, with pylons reaching the same height of 87 meters as the original Rama 9 Bridge.

The middle section of the bridge spans 450 meters, contributing to its total length of 780 meters. It originates from the inclined section of Rama 9 Bridge on the Thon Buri side, specifically in the Rat Burana district. It crosses the Chao Phraya River and connects to a 6-lane elevated road, intersecting with the Bang Kholae interchange in the Bang Phong Phang district. This connection allows direct access to the Sirat Expressway and Chaloem Maha Nakhon Expressway. In total, the project covers a distance of 2 kilometers.

Notably, the Department of Highways in Thailand conducted extensive simulations to test the bridge’s structural strength against wind forces. The results showed that it can withstand wind speeds of up to 270 kilometers per hour, equivalent to the force of a tornado. As a result, the bridge exhibits exceptional stability and resilience against earthquakes or storms. Epizilon Limited Company designed the bridge in a manner that ensures seamless integration and compatibility with the original Rama 9 Bridge, allowing it to blend harmoniously without standing out.

Construction

It was constructed by Ch. Karnchang Public Company Limited. The construction contract was signed on December 4, 2019, and work began on January 16, 2020. It took approximately 39 months (1,170 days) to complete, with a budget of 6,636,192,131.80 Baht. The pile foundation work started on March 15 of the same year. The final casting ceremony, officiated by Mr. Saksiam Chidchob, Minister of Transport, took place on February 22, 2023, signifying the completion of the bridge’s structural connection. Following this, additional tasks such as asphalt pavement, traffic marking, and minor architectural details were carried out. The project was finished as per the agreement on March 30. Currently, the bridge is undergoing various tests, including the decorative lighting system.

However, the construction of ramps on the Thon Buri side, which is not part of the bridge construction contract, remains incomplete. Challenges have arisen in relocating water and electrical pipelines, which serve as power supply points for Bangkok’s central business district, particularly the area from Sathorn Road to Silom Road. Limited working space has also caused delays in ramp construction. It is anticipated that the bridge will open to traffic in March 2024, initially allowing vehicles to travel as the first section of the Rama 3-Daokhanong-Outer Ring Road Expressway, from the bridge to Suk Sawat Toll Plaza. The full opening is scheduled for the end of the same year. Following the complete operation of the Rama 3-Daokhanong-Outer Ring Road Expressway in 2025, the Rama 9 Bridge will undergo significant renovations.

Check out the figures below for more technical details from the recent presentation at the 2022 SEAISI Steel Mega Event & Expo by EXAT.

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