Once a year, truck drivers in our region invite the people that are cared for in institutions for intellectually disabled children/adults to ride in their trucks, and they make a tour with hundreds of trucks. They are giving them a really fun day out. Many people stand by the road waving and the trucks sound their horns back to increase the joy. I think that is what is happening today. I don’t have any other explanation for all these trucks driving through the street, many of them with garlands and most of them sounding their horns.