Many businesses could be affected by a Government review of industrial activities close to motorways following the fire which has closed a section of the M1.
The review has been promised by Transport Secretary Philip Hammond and will focus on what can work go on under elevated sections of motorways.
A fire at a scrapyard under an elevated section of the M1 on Friday led to the road being shut between junctions 1 and 4 near London over the weekend as thousands of vehicles headed for FA Cup semi-finals at Wembley in north London.
Two lanes of the northbound section of the seven-mile route have since reopened but the southbound section was still shut this morning.
The Highways Agency said the southbound section would reopen "as soon as it is safe to do so".
A spokesman said updates would be issued throughout the day and added it was "hoping to reopen today".
The agency added that there were delays of around 30 minutes today on the M1 in the area of the fire,
A spokeswoman said: "Even though we have two lanes open northbound we are advising travellers to consider alternative routes."
Roads Minister Mike Penning told BBC Breakfast today: "We will do everything we can to get the southbound stretch open today, but sadly the inside lane on the hard shoulder was so badly damaged it is beyond repair and we'll have to do remedial work on that later on.
"We're looking to open two lanes south today and operate a contraflow using the hard shoulder on the northbound carriageway to have three lanes north and three lanes south."
He added: "I was a fireman for many years and I have never seen reinforced concrete damaged like this. There will be a review into whether combustibles should be allowed to be under motorways."
Highways Agency engineers worked through the night in an effort to get the southbound section reopened.
A spokesman said: "We are working in very difficult conditions in a confined space and have encountered unexpected difficulties in manoeuvring some of the large and heavy equipment required to reinforce the bridge deck."Reuse content