The Indian Railways announced Wednesday the concept of surge pricing for some of its premier trains on an experimental basis with the new system to be introduced starting Friday.

A number of trains, including the Rajdhani, Duronto and Shatabdi Express, will come under the new "flexi fare system" that is expected to bring in an additional revenue of 5 billion rupees (about $75 million) in the ongoing financial year.

“The base fares will increase 10 percent with every 10 percent of berths sold,” the Railway Ministry said in a statement, Indian media reported. The government also clarified that the differential pricing will not apply to tickets that have already been issued for journeys starting on or after Friday.

The ceiling for the increase has been set for 1.5 times the base fare — 50 percent — depending upon the demand. For AC two-tier coaches and chair cars, the maximum hike is set at 50 percent, while AC three-tier coaches will see a maximum hike of 40 percent. The new fare system will not be applicable to First AC and executive class coaches.

The government has kept other supplementary charges like reservation charges, superfast charge, catering charges and service tax unchanged.

The move has come under severe criticism from members of the opposition like the Indian National Congress’ Rahul Gandhi who said the country needs faster trains and not ticket prices, news network NDTV reported. Aam Aadmi Party leader Arvind Kejriwal, the current chief minister of Delhi, has demanded an immediate rollback of the plan.

In the face of the rising calls for an overturn of the flexi fare policy, news agency Press Trust of India quoted Railway Board Chairman A.K. Mittal as saying, “We will review it after some time and see what necessary measures can be taken further.”