After installing bio-toilets in almost all the train coaches, the Indian Railways is now mulling to replace them with "upgraded" vacuum bio-toilets, Railway Minister Piyush Goyal has said.In an interview to PTI, the minister said that to compete with the airlines, replacing the bio-toilets with the latest version was one of the plans the national transporter had for upgrading its amenities."We have started experimenting with vacuum bio-toilets like those in an aeroplane. Some 500 vacuum bio-toilets have been ordered and once the experiment is successful, I am willing to spend money to replace all the 2.5 lakh toilets in the trains with vacuum bio-toilets," Goyal said.As of May 31, 1,36,965 bio-toilets have been fitted in 37,411 coaches, at a cost of around Rs 1 lakh per toilet, according to railway ministry officials.There is a plan to install bio-toilets in around 18,750 more coaches by March 2019, when all the coaches of the Indian Railways will be fitted with such toilets, costing the national transporter around Rs 250 crore."By March 2019, we will be 100 per cent on bio-toilets, which in itself is a big achievement. The tracks will be cleaner, the smell will go away and rail renewal will be reduced," Goyal said.The vacuum toilets, which cost around Rs 2.5 lakh per unit, will be odour-free, will cut down water usage by 1/20th and have much lesser chances of getting blocked, he added.Hailing the Civil Aviation Ministry's regional connectivity scheme, UDAN (Ude Desh ka Aam Naagrik), as a great achievement for the country, Goyal said competition was good for the railways."As the prime minister says, now a person in hawai chappals can also afford to fly. It is a matter of great pride for this government that we are empowering the poorest of the poor. I also believe that it is great for the railways."This kind of competition will perk up the railways and improve our levels of service. As responsible public servants, it is our duty to give full satisfaction to the customers," he said.