rail crossings should not slowdown for trucks. As Ramps that goes higher does not.
Trucks slow down massively when going over a rail crossing, but when they go over a large ramp with 45 degree they dont slow down at all.
these should behave the same.
First - is may be safety measure. Like we have limited speed (to 30km/h, 50 when special light is lit) for rail crossings. Also ril crossing may have steeper angle which could lead to a jump and short flight at high speed. But i would say high speed may damage rails and also tires of vehicles.
Best sollution is to not use rail crossings at all - both vehicles and trains are then not slowed down at all.
bringing in a bit of realism, you really dont want to drive over speed bumps at full speed. sudden inconsistent changes like those or potholes arent great :)
For the people saying realism.. The ramp on the right.. they go full speed but the little rail crossing they slow down on. If they are going to make a jump the big ramp would be more likely a, steeper b, Taller.