Detours will be in place at the Narellan Road and M31 Hume Motorway interchange at Currans Hill from this weekend.
New beams will be installed on the Narellan Road pedestrian bridge over the Hume Motorway.
To minimise the impact to motorists, work will take place at night from 8pm to 9am on Saturday, December 9 and Sunday December 10, weather permitting.
Southbound lanes on the Hume Motorway will be closed from the Campbelltown Road exit to the Narellan Road off ramp.
Two detours will be in place, directing heavy vehicles along Campbelltown Road, and light vehicles along Blaxland Road.
Northbound lanes will be closed from the Narellan Road exit.
Northbound traffic will be detoured off the motorway, across Narellan Road to re-join at the eastbound Narellan Road on-ramp.
The northbound Hume Motorway on-ramp from Narellan Road westbound will be closed.
Motorists heading north from Narellan Road westbound will be sent via Camden Valley Way.
Access will be maintained for motorists travelling on Narellan Road with traffic control and a reduced speed limit of 40 km/h.