Transport Minister Andrew Constance is being urged to run the CBD light rail beyond 1am to move people from "alcohol-drenched precincts" once lockout laws are scrapped.

The union representing health workers has written to Mr Constance, asking him to expand operating hours of the new light rail when the laws are relaxed on January 14.

Transport minister Andrew Constance has been urged to extend the operating hours of the CBD light rail. Credit:Louise Kennerley

The CBD light rail will take its first passengers on Saturday, a month before the lockout laws are wound back in the CBD and along Oxford Street. The laws will remain in place in Kings Cross.

The secretary of the Health Services Union Gerard Hayes said Mr Constance needed to adjust the operating time of light rail to reflect changes to the drinking laws in the CBD.