That M25 terrifies me. Even when it's moving, you have joining traffic every few miles, so everyone has to shift over a lane to let them in. Going at 70 MPH, and they won't move over, I get panicky. Then we all move back to the left again. It's like a dangerous dance. But I've seen it at a standstill too. It's a horror! Luckily, I don't leave Norfolk now, and we don't have any Motorways here!