The Mountain Road is one way from Ramsey to Douglas for the duration of TT fortnight.
It was introduced at the Centenary TT in 2007, to try and eradicate head-on collisions.
Inspector Terry Stephen of the Roads Policing Unit says despite the change, people still need to drive and ride responsibly up there:
Campaign group brands Summerland inquest decision 'deplorable'
'Our pursuit for justice continues'
No new evidence to justify fresh inquests, says Attorney General in Summerland ruling
Decision follows campaign by victims’ families and lawyers who argued the original inquests were flawed and key evidence overlooked
Attorney General declines application for fresh Summerland inquests
Prolonged campaign has sought to re-open case
Mountain Road closed following road traffic collision
Anticipated to remain shut until approximately 7pm