Copper is used in all kinds of transportation equipment: electric transformers, railroad signals and street lights. It’s accessible and it’s valuable — that’s why it’s targeted by thieves who see easy money in stealing it. Law enforcement, utilities and insurance companies are especially hard hit. The Missouri Department of Transportation spent almost $1 million last year on repairing street lights caused by thefts of copper wire, said Derek Olson, a MoDOT traffic engineer.