Commuters have been promised faster journeys on Sydney’s new CBD light rail from this week amid criticism over the operating speed of the $2.9 billion service.

Travel time on the light rail, which runs from Circular Quay to Randwick, blew out to more than 50 minutes in December, prompting questions over the effectiveness of the 12-kilometre service.

Travel times on Sydney's new light rail will speed up by around 5 minutes, according to Transport for NSW. Credit:Louise Kennerley

Journey times have recently sat somewhere between 45 and 50 minutes, but that’s expected to be reduced to 40-45 minutes from Monday.

While the speed limit on the light rail won’t change, a Transport for NSW spokeswoman said journey times would improve after more services are added to the network, dwell times are reduced and "teething issues" are resolved.