A tree fell across my driveway and I can't get my car out — what should I do?

Trunk lying across the drive with vehicles boxed in or locked out, canopy sprawling into the ditch or the road, and typically a lifted root plate standing at one end like an open door. Walk the full length and check the far end before anything else — the canopy is where a service drop gets caught. Primarily an access and egress problem rather than a structural one. The tree has already done the thing you were afraid of. The hazard that remains is stored energy in the wood — trunk sections under bind, and spring poles among the bent saplings underneath — which is a cutting hazard, not a falling one.