In the 1960s there was a sand trap at Ninewells junction on the main Dundee to Perth line which I assume was to stop runaways from the Newtyle railway running onto the main line. The line up to Liff station was long and fairly steep so a runaway would have gathered a fair speed. The trap consisted of a wooden box encasing both rails for a fair distance filled with sand, although due to a cliff face the trap turned towards the main line so if it did not stop the runaway it would still have gone onto the main line. Were they effective? could they slow a goods wagon or a locomotive? What if sand was wet and heavy frost, did the trap still work? Did it stop the runaway or did it usually de-rail? Are they still used in modern times ?