The challenge encourages signers-on to spend a week the same way 30% of Allegheny County residents do — never personally driving a car. Next week, a coalition of activists, advocates, and electeds is urging Pittsburghers to forgo using a car. From Monday, Sept. 30 to Sunday, Oct. 6, participants in the inaugural Week Without Driving PGH will avoid driving, instead walking, rolling, cycling, or taking transit or a rideshare to their destination…