ERDF ('Electricity Grid of France') vehicles on their way to lunch approaching the pinch-point in rue Chaumont-Patin.Eglise de Notre-Dame-des-Echelles sticks out at an angle, making the main road out of town narrow. Those going up the hill and leaving town have right of way, but if you are coming into town you have to enter the problem zone before you can actually see if anyone is coming, so those with right of way frequently end up giving way to people coming the other way, through no fault of theirs.
Probably what triggered this move to trial traffic lights was the destruction of a corner pillar at the old doctor's house by a truck trying to squeeze past about 12 months ago. Heavy vehicles use this road a lot, as it is the main road to Loches and Preuilly does not have a by-pass like many towns in the area because vehicles have to cross the river Claise. Crossing the bridge brings them right through the middle of town. Moves to reduce the parking on the Grande Rue have already been put in place, so the traffic lights are part of an ongoing plan to mitigate the traffic issues.
Someone in town doesn't want the traffic lights.