Junction 10 of the motorway was closed at 8pm on Saturday and is not due to reopen until 5am on Monday to allow the frames of the bridges to be filled in.
There are delays of around 30 minutes on the motorway while motorists are diverted up and over the junction near Walsall, while nearby local roads are also busier than normal.
It is the third time the junction has been shut in the last three months as part of a £78 million scheme to revamp the junction and speed-up travel times.
The first two closures saw 120-tonne steel beams lowered into place by a crane so big it needs to be transported in parts and then built at the scene. The beams for the north bridge were installed in August and the south side in September, with the junction shut for a full weekend both times.
This weekend, around half of the bridge deck panels are being lowered onto the beams.
The remaining panels will be installed during nighttime work over the next week and a half. The junction will be closed from 8pm until 6am, with the same 'up and over' diversion in place, each week night until October 20 as a result.
The new bridges over the motorway will have four lanes, rather than the current two.
Highways England has encouraged drivers heading north or south to use the M1 while the junction is closed.
Transport for West Midlands reported slight congestion on the Black Country Route and Wolverhampton Road on Sunday morning but warned the roads were likely to be busier in the afternoon.