train tracks

hey, i made some train tracks in my map whit the correct settings and that stuff (rail width 6, space between rails 80, rail height 10)

but when i make a train on my map, and go faster then about 40-60 it just fails, my weels wil go IN to the tracks and my trail freaks out and sometimes my Gmod even crashes 0_o

anyone know someting for this?

maybe you should try prop tracks.
my train did 100mph on it.