Thailand’s proposed US$1.47 billion underground route

A new US$1.47 billion underground expressway route is being proposed for Thailand’s traffic-choked capital, Bangkok. Building the 6.3km underground tunnel stretch for part of the N1 Expressway project could help alleviate the city’s chronic traffic congestion, which is amongst the worst in the world.

The project has been put forward by the Expressway Authority of Thailand (Exat). The route would run underneath Ngarmwongwan Road and link with the N2 Expressway.

However, the proposals have met with some resistance from locals. Building an elevated expressway stretch instead would cost around $500 million. An environmental study will be carried out in 2025. Should the project get approval, construction would start in 2026 with completion expected by 2031.

Meanwhile, building a bridge to link Trat Island with Koh Chang is expected to cost $293.5 million. The estimate comes from the Expressway Authority of Thailand (EXAT). A feasibility study will be ready in 2026 and will evaluate key factors including the depth of the sea and the effects of tides and sea currents.