Nilgiri mountain rail entering the tunnel at Kety village area. Diesel engine coming from Ooty to Coonoor. Diesel engines are used between Ooty to Coonoor. From Coonoor to Mettupalaiyam downhill steam loco is used and the engine is always at the downhill side, i.e. while coming uphill the engine will push the carriages from behind and while going downhill the engine is at the front preventing the carriages running away if coupling breaks. By Ken, June 2003.