To give Timmy a direct answer, trains make a lot of noise because they are very large and because they have a lot of cars to make noise when going fast. When going slowly, they are pretty quiet except for the locomotives. The diesel engines in the locomotives make the most noise excepting the warning horns. Electric locomotives are very quiet except for when sounding the horn. One heavy-duty truck-tractor pulling a semi-trailer (total of 18 wheels) at freeway speed is VERY noisy. Large tires at freeway speed are VERY noisy. Trains also make very different kinds of noises than road vehicles. Their wheels make clicks running along the rails and make squeals when in curves in the track. Can anyone else do better than this in just a few words?