I agree with unimogbert, an EQ isn't a scenario where you'll have to befriend hostile natives, learn a new language, join the local tribe, fight to the death with the largest in the dominant clan, and marry the native princess to get along and survive in a new world: your new world is defined by the bridges on either side of you, and whether there are points of civilization between those bridges. If you took the essential traveller advice, and left word with someone of where you were going and kept to your itinerary, unless that person is lost in the EQ, someone will be coming to get you, eventually. Alot of someones will also be doing aerial surveys of the roadway and bridges to assess damage and pick up those trapped by structural collapses, eventually. Communities that are cut off will want to be fed, eventually. County commissioners will want to make sure that these people get fed and rescued in this scenario, else they lose in the next election. Aerial rescuers will be looking for cars, bikes, people on foot - they'll be traversing the entire roadway. So stick to the roadway, and make yourself visible. Carry a map - if you can safely walk to the nearest village, or at least walk to see if the bridge is out before that village (most habitable locations tend to be at or near water for some reason), do it - you may see others who are trapped with you, or at least be able to wave at them on the other side of the chasm. If they're organized, they can get you across or point you to an alternate crossing. You won't be alone then.

A 200 mile march over unknown hostile is a fool's errand here. Bring water and food, shelter for warmth, comfortable boots, and changes of socks etc. It would be good to have something visible to lay in the road and mark your location to aerial surveyors, or your direction if you decide to take off and walk. Be prepared for the normal variances in weather and heat/cold. I think a bike would be extremely helpful in covering more road ground quickly - but every foot venturing off the road will decrease your chances of rescue. Make your attempt to reach the nearest civilization, but be prepared to wait.