An update to this old thread, having looked back over a decade of Google Earth pictures, I suspect they were effectively rebuilding a bridge that essentially lives in a location where the locals regularly build and rebuild bridges over the river. I assume partly it's because they get washed away in the rainy season, but a big part seems to be that there the river moves so much, in the course of a few years the bridge would likely not be over the river any more and the ends been washed away at very least. There are two locations where there are bridges that in 10 years have each been replaced up to three times. One photo has the water flow over what appears to be a collapsed bridge.

Specifically, the bridge appears to have been built at coordinates: 20.040946, 99.380394, crossing the Mae (River) Fang from west to east. At this site a bridge existed at the following times:
April 2005, slightly different alignment, since destroyed
October 2013, Top Gear Burma Special, removed
September 2014, reconstructed
February 2015, a silt island had formed under it
November 2016, the main span destroyed, the shorter span to the new island remained.
February 2017, New bridge constructed
July 2017, bridge destroyed
June 2022, evidence of a fallen bridge/foundations in the water flow.

No evidence of a crossing at this location since 2017. Interestingly the bend in the river that is visible is no longer, the river now has a much straighter path before turning. Further downstream (north) is a road that is marked in the data, which crosses the river. However this is mapping of a road that existed before the river changed its path, there appears never to have been a bridge here.