It is part of ongoing protests at the entrance to Third Energy's site in Kirby Misperton, near Malton.
Habton Road has been closed since around 11.15am today when the anti-fracking campaigner scaled the vehicle.
A North Yorkshire Police spokesman said: "This irresponsible action is extremely dangerous. As a direct result, Habton Road is now closed, and this will cause significant disruption to the local community.
"Officers are at the scene assessing the situation, and diversions are being put in place."