Located in Samut Songkhram, Thailand, around 37 miles west of Bangkok. Looks like any other open-air market in Asia. The market is sheltered by low-hanging awnings / umbrellas and if you look closely, you will notice that you are actually walking on train rails. Then a piercing siren sounds and in a flash the market transforms - the shoppers disappear and the stallholders whip away their produce. One moment you see the locals shopping for their vegetables and the next moment the vendors will scoop up their baskets and boxes and anything that lies over the track. The market comes to a standstill as all the vendors hold on to the poles supporting their awnings to make way for the train to pass. It is such a tight squeeze that the train travelling at about 15mph almost touches the fruits, vegetables and everything else at the marketplace as it passes through. Once the train is gone, the vendors push back the stalls and awnings into position and everything goes back to normal as if nothing has happened. Do note that the train schedule is subject to change so check the schedules with the train station before planning your journey to Maeklong.
* video of a train going through a tightly packed market, where market stalls are set up on the rails.