Roadworks between Lithgow and Bell will add another degree of difficulty for motorists travelling between the Central West and Sydney. Drivers have been blocked from using the main Great Western Highway since March 9 after cracks were found along the historic Convict Bridge at Victoria Pass, between Little Hartley and Mount Victoria.

That closure has forced traffic onto the Bells Line of Road, however new nighttime roadworks announced on Thursday will now cause delays on that road as well.

In a traffic alert released just after 5pm Thursday, Transport for NSW urged motorists travelling between Lithgow and Bell to plan ahead, with night roadworks set to begin on Chifley Road from Tuesday, April 7, bringing delays and changed traffic conditions for nearly two months.

Road crews will carry out heavy patching, asphalt relaying and line-marking.

Transport for NSW said the works will continue through to Tuesday, June 2, weather permitting, and will take place overnight between 8pm and 5am from Sunday to Friday. No work will occur on Saturday nights or public holidays.

During work hours, motorists can expect single lane closures and a reduced speed limit of 40 km/h through the affected sections.

Drivers using the Great Western Highway detour via Darling Causeway and Chifley Road are advised to allow extra travel time, with delays of up to 30-35 minutes possible.

"This road maintenance work is expected to cause additional delays of up to 10 minutes," the Transport for NSW alert said.

Further information is available via the Live Traffic NSW website or mobile app.