This is a very common engineering challenge, but I don't have experience with the specifics of rails.
Roads (especially near bridges) have expansion joints so that the sections can expand and contract in hotter/colder weather. It looks like slab tracks just have more support and try to fight expansion. This will increase the load required to buckle the tracks, but it will put the entire system (slabs, rails) under more stress.
In other industries this can really affect the entire design of mechanisms. Motor mounts in cars look to allow thermal expansion between the hot engine components and the chassis without letting the whole thing shake apart by being too loose. You can make designs such that they are very close to being statically determinate, meaning there is only one restraint for each of the 6 degrees of freedom, so relative thermal expansion doesn't stress and fatigue adjacent structures. However, that means that adding redundancy in case a single support failure can be quite tricky...
One area where thermal expansion is very challenging is fasteners. I've seen some machines where the joint had to be different materials than the fasteners, and it had to survive a wide temperature range, so the torque on the fastener, including testing it and calibrating the tools, became extremely critical.
Roads (especially near bridges) have expansion joints so that the sections can expand and contract in hotter/colder weather. It looks like slab tracks just have more support and try to fight expansion. This will increase the load required to buckle the tracks, but it will put the entire system (slabs, rails) under more stress.
In other industries this can really affect the entire design of mechanisms. Motor mounts in cars look to allow thermal expansion between the hot engine components and the chassis without letting the whole thing shake apart by being too loose. You can make designs such that they are very close to being statically determinate, meaning there is only one restraint for each of the 6 degrees of freedom, so relative thermal expansion doesn't stress and fatigue adjacent structures. However, that means that adding redundancy in case a single support failure can be quite tricky...
One area where thermal expansion is very challenging is fasteners. I've seen some machines where the joint had to be different materials than the fasteners, and it had to survive a wide temperature range, so the torque on the fastener, including testing it and calibrating the tools, became extremely critical.