Or take a tip from the Railways and have a deadman switch, without the resultant slamming the brakes on (for all you smart ar$e$ out there).
Every 15 min a ping sound goes off, and you have to reach up or over....somewhere a little of a stretch and tap a pushbutton. If nothing is received it pings and pings at a faster rate....... and finally the electric cattle prod inserted in the front seats thinks you are a cow
.
Problem solved!
J
