“To begin with, we have introduced the controlled discharge toilet system in some coaches. The system ensures that waste from the toilets are discharged onto the track beyond a predetermined speed of the train. Which means waste is discharged beyond stations and not within the premises of the stations,” an official said.

Vacuum retention toilet, which are used in airplanes, works on vacuum-assisted suction of waste. Its retention in an underslung storage tank and final evacuation is at terminals through a ground installation provided for the purpose.

The world’s largest railway network transports about 16 million passengers on about 8,000 trains every day, spreading 300,000 litres of human waste from open-discharge toilets.

As per the government policy for total sanitation by the year 2012, the Railways has taken up the project of development of environment-friendly toilet system as part of its technology mission on railway safety.

On the biodegradable toilet, the official said four toilets have been fitted in one coach of Prayag Raj Express as a pilot project.

“Based on the results of the field trials, a final view shall be taken on the type of environment-friendly toilets to be adopted on coaches of the Indian Railways,” said the official, adding that the aim is to achieve the target of total sanitation by 2012.