Flood Street has been closed while construction continues on the Wednesday to Brierley Hill tram extension.
Two-way traffic lights have also been installed on King Street as part of the work.
The project is seeing the tram line extended from Wednesbury up through Brierley Hill, bringing light rail to Dudley.
The existing route goes between Wolverhampton and Birmingham.
Midland Metro Alliance tweeted: "Flood Street, Dudley is closed for up to four weeks and there are two-way traffic signals on King Street to allow for the ongoing construction of the #WednesburytoBrierleyHill Metro extension."
It comes as there are calls to extend the tram network into Great Barr.