The M62 has been shut in both directions between J35 and J37 after the device was found in East Yorkshire. A 500lb (227kg) explosive was identified by construction workers at a new development in Rawcliffe Road, Goole, on Thursday.
Police put in place in surrounding areas on Thursday evening and restrictions remain.
A no-fly zone above the area has also been activated.
A bomb squad has been on the scene for more than 36 hours and officers confirmed the device is “live”.
Humberside Police said plans are in place to safely detonate the device.
Up to eight homes in the area have been evacuated and residents in the wider area have been asked to remain indoors.
Some businesses near the construction site have been told close.
Authorities imposed a 1600m vertical no-fly zone over the site from 8pm on Friday to at least 3pm this afternoon.
In a statement, the force said: “Colleagues from the Explosive Ordnance Disposal (EOD) team, who have been on site since late [Thursday] night, have now confirmed that the device is live and are making plans to safely detonate the bomb within the next 24 hours.
“All persons in the immediate vicinity have been evacuated as a precaution.
“Those living or staying in the wider immediate area are asked to remain indoors from 8pm this evening.
“Businesses within the cordoned area will be asked to close until the works have been completed.
“Road diversions will be in place across all affected roads from 8pm this evening. For drivers using the M62, visit the Highways England website.”
This is a developing news story, more to follow.