The A27 is closed today after the tragic crash at the Shoreham airshow on Saturday.
The section of the road to the north of Brighton City Airport remains closed with a 22km long diversion in place around the scene.
Highways England is waiting for access to the road to assess the damage caused when the Hawker Hunter aeroplane crashed into the highway.
A spokesperson for Highways England said: “At this stage it is impossible to say when the road will be open.
“We don’t have access to that road at the moment, it’s under police investigation so at this stage we wouldn’t be able to say how long it is likely to go on for in terms of the closure and what work would need to be done.
“We do not have access to the road to assess what needs to be done to make it usable again.
“Once the police have done [with the investigation], we can then have a look at it, and assess what needs to be done from an engineering point of view.”
Surrey and Sussex police were unable to say when the road will be open, and warned of long delays to motorist journey times.