Two huge bridge-like structures were carried by a crane on the M6 motorway before being installed.
The M6 was closed between junctions 14 (Stafford north) and 15 (Stoke-on-Trent) to enable the two 38-tonne gantries to be fitted.
The motorway closed at 9pm on Saturday and was open again by 8am on Sunday with both gantries in place.
The gantries had been built off-site and were transported to the M6 site on trailers, with an abnormal load escort, from the north-east.
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On Saturday they were then lowered onto pre-constructed foundations and posts using a specialist 160-tonne crane.
Signs and signals will be fitted to the gantries which will set variable speed limits to help traffic flow more smoothly, close lanes when necessary and provide travel information for drivers.
Highways England Smart Motorway Project Sponsor, Peter Smith, said: "This is the first time we have attempted to install two superspan gantries in one night on this scheme and it was quite a challenge to get them both put in place and the M6 open by 8am.
"Thanks to careful planning and the efforts of the team on the night, everything went smoothly and we were able to get the motorway open shortly after 6am to minimise disruption for motorists.
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"We appreciate that our work to upgrade this stretch of the M6 can cause some disruption and we are always grateful for people’s patience while we carry out such major works which will ultimately mean better and more reliable journeys for road users."
The installation at the weekend follows a similar engineering feat earlier this month when an 800-tonne bridge was removed from over the M53 near Birkenhead.
