Part of the A12 in Essex is still closed more than 24 hours after a driver was killed when his lorry crashed off a bridge onto the road below.
The HGV burst into flames after landing on the southbound carriageway, near Witham.
Recovery teams have been working to remove the wreckage from the scene.
The HGV crashed through the barrier of Coleman's bridge over the A12 at Witham.
The 30-year-old driver who was from the Witham area died shortly afterwards.
Dawn Hucklesby was travelling northbound on the A12 when she saw the crash.
She said: "I noticed there was lots of debris in the air, there was a lorry about three or four cars ahead of me and I thought it was coming off the top and then I glanced over to the right and I couldn't believe what I saw.
"In the air was railings or debris from that and it was a van or a lorry it had come off the bridge and landed in the trees and on the side part there, there was a slight bit of smoke and then big thick black.... we couldn't see we couldn't breathe, I had to put my scarf up because I couldn't breathe it was that bad."
The lorry was carrying large batteries used by buildings in the event of a power cut.
Chief Inspector Nick Lee, Essex Police, said: "It's obviously a very large scale incident with lots of damage caused to the road infrastructure.
"The main problem at the moment is that the goods that were carried by the lorry are difficult hazardous chemicals and we're engaging specialist recovery people to deal with them and that's causing significant delay at the moment."