Yes, this is an issue. After about 60 kilometres per hour, you cannot use level crossings, so you need small bridges flying over the level lines.
I think you can do it in two ways: the European way or the U.K. style. In Europe, it's not really a cost driver. If you're looking at capex projects to build the bridges.... I'm not talking about the rail bridges. I'm talking about for street bridges. They are not driving the costs. If you are looking into high-speed, too, this is an issue. They build very complex bridges to cross the rights of way and level lines. In the U.K., it's unfortunately the case that it's very expensive to build them. It's completely different if you're looking into mainland Europe.