Isle of Man TT organisers have implemented a new red flag procedure following the incident with a course car involving rider Steve Mercer.
Clerk of the Course Gary Thomson announced the changes after the incident, which left Mercer in a critical but stable condition, that occurred when the riders were making their way back to the Grandstand start/finish area following the crash claimed the life of Dan Kneen.
Wednesday night's combined Superbike/Superstock/Supersport practice had been red-flagged 10 minutes in, due to Keen's crash at Churchtown, and Jackson Racing's Mercer collided with a course car on its way to the initial accident.
Mercer was airlifted to Nobles Hospital on the Isle of Man before being transferred to a hospital in Liverpool.
A statement from his wife Caroline confirmed he had suffered "serious injuries".
In a bid to avoid similar incidents in the future, the new procedure has been implemented, which will take effect from tonight's running.
If a red flag is shown, regardless of where on the 37.75-mile circuit it comes out, it will be deemed as a full-course red flag.
Riders will be forced to stay where they are on the circuit until the incident has been cleared, no matter how long that may take.
They will only be able to move under the control of the travelling marshals.
Thursday's practice is set to get underway at 1820, and will follow Wednesday's cancelled schedule of a combined Superbike/Superstock/Supersport/Newcomers session, followed by an outing for the Sidecars and a lap for the TT Zero machines.
Earlier on Thursday, Kneen's father Richard gave his blessing for the Tyco BMW team to "crack on" following his son's death.