This includes mobile toilets exclusively for women commuters if such a facility is not available, the NGT bench of Justice V R Kingaonkar and Ajay Deshpande ordered on November 3.

The green court's directive came as an ad interim relief during the hearing of an application filed by law students Mukta Sathe, Sanjay Jadhav and others on the human dirt management issues arising from conventional system of direct discharge toilets of the Indian Railways' trains and the need for bio-toilets.

The tribunal directed the environment directorate, Indian Railways and the central and the Maharashtra pollution control boards to submit a comprehensive report regarding human dirt management on railway tracks and plan of action to curb environment-related problems, and whether bio-toilets have been introduced on any route in the Central Railway region.

The matter has been posted for next hearing on December 18 after the lawyer representing the railways submitted that an affidavit would be filed within four weeks.

According to the plea, nearly 3,980 tonnes of human waste is dumped every day through the open discharge system toilets used in the railway coaches and the need is to find out eco-friendly alternatives.

Lawyer Asim Sarode, representing the applicants, said, "The problem of pollution caused by open discharge system is not just confined to the railway tracks but also the surroundings such as water bodies and air. Fecal matter discarded when the train is in motion gets dispersed to surrounding areas, leading to air pollution and unpleasent odour."

"There is no system to prevent contamination of river or lake water caused by discharge of fecal matter when a train passes over a bridge on such water bodies," Sarode added.

The applicants argued that Indian Railways had become the biggest mobile source of environmental pollution. They cited a CAG report which mentioned that despite two decades of experimenting, the railways were still conducting trials with different types of green toilets and had not been able to finalise the technology. The Integrated Railway Modernisation Plan for 2005-10 had set a 2007 deadline for the selection of the technology and large implementation by 2010, they pointed out.

They claimed that the move to install bio-toilets, which is an eco-friendly form as it converts excreta into neutral water using a form of bacteria, had failed to take off in the right earnest.

Among other things, the applicants have sought directive to the Railway Board to enter into contract with only those coach manufacturers who provide eco-friendly bio-toilets in railway coaches.