I don't have any first hand knowledge, oh how I wish I did. But since your question inspired me to get resolve an issue I've been paralyzed by, I thought I should at least say thanks.
I was looking at a couple of sites that sell the flatbeds, and I think I could actually handle the concrete abutments which is what most of the install is about. What kind of education were you able to find or do you have a background that makes you familiar? I'm coming from having never poured a post hole but I thought bridges were out of my league for life. It took me 5 mins to realize this is in my capacity and im quite excited, I don't know if these will be available on an island where i'll end up but I'm inspired flat out as a designer.
I seen a shipping container bridge. It was meant for ATV's and a tractor. As far as a car of truck, I believe it would get a little narrow.
I have also seen a flat rack for a bridge, basically, a shipping container without sides. I like this better than the container but it is still a little narrow for my liking.
Railroad flatbeds run around 85' and support a lot of weigh symmetrically from the centerline and are wider.
I am a civil engineer by education. I worked for Amtrak for three years in their bridge dept. That was awhile ago now and I traded that work in for something different.
I see there are two schools of thought about whether to use poured abutments or pilings. or this picture.
Interesting picture of the rail car bridge, Saybian. The rail car is upside down! That pocket on the abutment is what the containers latch to. Very strong place, great idea. I'm retired now, but built bridges for a living in Southern California. The first critical issue with a bridge is it's span. If your span is less than 30 feet, a rail car is probably overkill. Plus you need fairly straight access for the rail car and access for a crane. I could never get a rail car down to our creek on the logging roads. The second issue is the load on the abutment. When the vehicle is over the abutment, the abutment must carry half the bridge load and all of the vehicle load without failing or sinking into the ground. Sinking is prevented by pilings or spread footings distributing the weight over a larger area. The area around my creek is clay, which seems very firm, but will ooze when wet and under load. If you have a way to pick up one end, you can add to your abutment to raise or level it if it sinks a little.
I was thinking of using 4x12s and 2x4 spacers with galvanized all thread on concrete abutments. That way I could assemble it at the crossing. I have to keep my abutments back from the creek. Our county/state are very strict about getting material in the creek bed.
I may be over doing this.... I built bridges for Caltrans in earthquake country!
P.S. Here in Northern California there are a lot of rail car bridges.
This has been on my mind for quite some time too. It seems more and more like the perfect solution for my creek-crossing dilemma.
I'm wondering about logistics: Where do you get one of these things? How do you transport such a thing to a remote location (is it straightforward to get onto a truck?)? How much would you expect to spend?
I'm also thinking they would support quite a lot of weight. Could a car/tractor/elephant/heard of cows cross safely?
Thank you Permies.com for existing and for connecting me with people who also exist!