This is the heart-stopping moment a reveller walked along an unfinished motorway bridge in Thailand.

The female tourist sparked panic as she climbed without safety gear up the Skytrain bridge pier in Samut Prakan, on the outskirts of Bangkok, on April 27.

Horrified onlookers screamed as the woman stepped dangerously close to the edge of the structure, swaggering with arms outstretched over the busy road. They called a rescue team, fearing she would slip on the wet concrete and plunge to her death.

Volunteers later arrived and collected the reportedly drunk holidaymaker.

Local Tanapong Suksin said the woman may have downed cans of beer while celebrating the Wan Lai water splashing festival.

He said: 'She appeared to be drunk when she climbed onto the construction site. Luckily, the police acted quickly and saved her. We were scared because she kept looking up at the sky and not where she was walking.'

Officials have not clarified how the woman was able to scale the motorway bridge.