Rail operator SMRT Corp has acquired a fleet of special track vehicles to accelerate its sleeper replacement programme.

So far, four of the so-called Road-Rail Vehicles have arrived. They will mechanise the replacement of sleepers (thick timber planks on which rail tracks rest), a process that has been largely manual till now.

The vehicles will be able to replace 140-150 sleepers per night, up from the 90 or so possible when done manually. These vehicles will help complete the sleeper replacement programme in 2016 - instead of 2019.

So far, SMRT has replaced about 10 per cent of the 188,000 worn sleepers on the North-south, East-west lines - the oldest lines in the rail network. Worn sleepers can result in a rougher ride for commuters, and in extreme cases, pose safety risks.