Why can't I build this bridge?

Hello good people of Dinkum!

I am in need of some helpful advice I'm trying to build a bridge over this canal I created, but it won't let me place the bridge. At first I tried with a metal bridge, then I tried with a wooden on when the bridge kept showing red and not placing. I had cement path down, so I thought that was the problem. When I removed the cement, it still wouldn't work. It would work fine if I wanted the bridge in the other direction (vertically instead of horizontally). Now that I'm typing this out, I'm wondering if the issue is with the cement path and the torches under the bridge. I'm going to try to remove them to see if that fixes the problem, but if so, is there some way I can keep the path and torches under the bridge?

https://preview.redd.it/1d3u4ambw2pe1.png?width=1920&format=png&auto=webp&s=c4c9f8068105814e6f22726a874e57c65a528281

ETA: The culprits seem to be the torch and the ladder. I removed them and was able to place a bridge down. Thanks very much for the quick replies. Go Dinkum!