Calcutta: The road surface on the Parama flyover's Ruby-bound ramp has been scraped off but mastic asphalt hasn't been laid on the entire stretch for lack of time.

The Calcutta Metropolitan Development Authority (CMDA) has sought more time from police to complete the work on the 988m stretch.

The ramp was closed on November 24 and 25, and from December 1-3.

"It took a lot of time to scrape off the top layer before we could start laying mastic asphalt," a CMDA engineer said.

The CMDA wants its engineers to work at nights on weekdays to get the work completed at the earliest, an official said.

"We can use the nights and work for 30 hours spread over five days. Daily six hours at night will hasten the work," an engineer said.

The flyover's road surface began to wear off in several stretches within three months of its inauguration in October 2015. Metro had reported the matter in January 2016.

The CMDA has been relaying the flyover's road surface with mastic asphalt over the past year. Work is left on three ramps - the Ruby-bound, the one that connects to the flyover opposite PC Chandra Gardens, and the arm connecting the flyover to the AJC Bose Road flyover.

The top layer of the Ruby-bound ramp had worn out in several places. The stretch would have worsened further in the absence of immediate action, an engineer said.

Mastic asphalt doesn't let water to percolate down and so the surface is more durable than bitumen, another engineer said. Water is the biggest enemy of bitumen and results in road decay.