if I am not mistaken the roads that are signed in one direction for ORV are still two way roads. unless the road in question has "one way" signs posted with an arrow of direction.
secondly if the sign says mixed traffic that is ok to ride if its marked ORV. theres alot of those up around Rose city.
as for crossing the street running...thats for 12 ands under.
check the home page of the link if you want a map book. the guy who does them marks out every road thats legal.