A few years ago, I was about 5 miles up a old trail in the Sierra Nevada Mountains when I encountered two young men pushing a wheelbarrow with a gasoline powered dredge in it. Now this was not a light load and they were going uphill. I have always remembered that incident.
Ever since then I have considered wheelbarrows as another source of transportation. In a bug out situation or merely for moving supplies always try to use wheels. Save your back.
Make sure you have wheelbarrows that have deep sides so you can fill them and not tip over. Do you have extra parts for it – extra wheels or tubes? Make sure the handles are maintained so there are comfortable to push. You can use foam rubber insulation and cover with tape.
Children’s wagons are another possibility, you can build up the sides, remember when you had one and pulled your puppy around in it. The handles can be fixed to attach to a bike.
I have a flower cart with wheels; it can easily be covered and pushed. You can use like an old fashion pushcart.
An old lawn mower: it has four wheels and if you take the engine off its perfect.
Skateboards: A skateboard and a backpack, it is amazing how fast and far some of the kids in my neighborhood can travel
It might not hurt to have spare wheels in your storage, wood can always be found to make some kind of cart. A rule is the larger the diameter of the wheel the easier the cart will push.
Remember with age knees and backs wear out. Use your imagination to keep the weight off them, you may want them to last.