I feel like a lot of people are commenting without much context. These bridges are for legal footpaths. They’re usually in the countryside. The paths aren’t maintained they’re just a legal right of way through the countryside and they have a legal obligation to put a bridge so as to not obstruct it for people on foot. It’s not like a trail as in the US. The paths aren’t even remotely wheelchair accessible for miles either way they’re usually mud. You would have to climb over stys to get to the bridge. The bridge would be the least of your problems.
And the point of this is to be able to close high-risk at-grade crossings of the line, especially those with relatively poor sight lines or where the necessity to maintain sufficient sight lines is an impediment to increasing the line speed.
It wouldn't matter. In (most of?) the US, anything you so must meet all the latest code, so if you aren't rich you line in a tent (I'm exaggerating slightly, but you are forbidden from a building a 1970s car, house, etc)
The US ADA requires reasonable accomidation, which is wishy washy, but lots of new construction nature paths in hilly terrain just have steps, because there's no room for a ramp and an elevator would be unreasonable.
Even new construction train stations don't always get an elevator to go over or under the line to the other platform... although they do get a long ramp and a ramp on the platform to load if the car floors are above the platform.
If these crossings are really in the middle of nowhere along muddy footpaths, I think you could get away with no ramp in the US, too.
If the government built a train station on the middle of the trail, then they would literally be required to build ADA-compliant ramps down to the mud.
