I'm also having a hard time believing that Philly has half a billion dollars worth of traffic signals.... Unit costs can be misleading if they're hiding a lot

I'm also having a hard time believing that Philly has half a billion dollars worth of traffic signals.... Unit costs can be misleading if they're hiding a lot of non-recurring engineering costs. I can easily believe it would cost $175,000 (or more) to replace a single set of traffic signals, especially if they are built from scratch and need to interface with some ancient system. However, the 2nd, 3rd, .... 3,000th signals ought to be progressively cheaper as things get worked out.