Road supervisors will examine the reasons behind the "unprecedented" traffic delays near the Download Festival.
On Wednesday and Thursday, thousands of people descended upon Leicestershire's Donington Park, severely congested the M1, A50, and A453.
For some, the wait to enter the site was longer than seven hours.
Plans will be put in place to prevent this level of disruption from happening again, according to National Highways, which oversees the road network.
Some of the 100,000 ticket holders were allowed entry to the sold-out event on Wednesday.
Long delays were experienced by East Midlands Airport travelers due to the site's congestion, and some even missed their flights.
Festival director John Probyn issued an apology as a result.
National Highways stated that it would be investigating what went wrong.
The problem, according to operations director Mark Munnoch, was getting people to the site. They were all funneling into Download, which caused a backup that extended all the way back to the freeway.
In addition to Download traffic, it was having an impact on everyday commuters and other road users. ".
He claimed that although National Highways attempted to clear the roads as quickly as possible in cooperation with Download organizers and East Midlands Airport, the reason for the delays was still unknown.
We will analyze it, Mr. Munnoch said, adding that it was difficult to pin down right now.
"The effect of what we witnessed last week was unprecedented, especially the backlog of traffic on the strategic roads, such as the larger A-roads and the motorways.
We were very concerned to see those gridlocked, but we will make sure to take note of the situation and make plans to prevent it from happening again. ".
For the first time, the festival celebrated its 20th anniversary by hosting four headline performances.
The Leicestershire Police issued a warning on Sunday advising festival attendees to avoid unintentionally dialing 999.
The police force reported that over the weekend, it received more than 1,000 calls to its emergency number, compared to around 750 on a typical "busy" weekend. Some call takers reported hearing loud music in the background.
