Halifax Regional Police say a driver appeared to lose control of his vehicle before he was ejected from it.
It happened Saturday afternoon in the outbound lanes of Highway 102 near Exit 1.
The 25-year-old man has been rushed to hospital where a trauma team has been activated.
No other vehicles were involved and police have not released any more information at this time.
As of 4 p.m. police were still on scene and asking those needing to pass through the area to find another route.