Exit Only, Mile 127, and the Vanishing Fuel Margin
You are eastbound on an Ohio interstate at night in a rental car. You just passed a green mile marker reading “127.” Your destination is Exit 129, airport. An overhead guide sign says “Exit 129 - Airport, 1 MILE” with a down arrow over the right lane, and a yellow “EXIT ONLY” panel sits above that lane. You are in the center lane; a semi is in the right lane slightly ahead. Your low-fuel light just came on. A blue service sign earlier listed gas at Exit 127, which you believe you have just passed. Traffic is moderate. Your indicated range is about 30 miles, but the estimate has been dropping, and your passenger is asleep.
1. Using mile marker 127 and the guide sign, how far is Exit 129, and what does that imply about the gas at Exit 127?
Read the worked answer
Mile markers count distance along the route, so passing mile 127 means Exit 129 is roughly two miles ahead, consistent with the “1 MILE” guide sign appearing soon after. Exit 127 is at or behind your current position; the gas listed on the blue service sign for Exit 127 is likely already past the gore area or immediately behind you. Do not reverse on the shoulder or stop to reconsider. Use the mile markers to estimate the next services and decide whether the indicated 30-mile range gives you a safe margin to Exit 129 or to a later exit.
2. What does the yellow EXIT ONLY panel mean, and how should you move right around the semi?
Read the worked answer
The yellow EXIT ONLY panel means the right lane becomes an exit-only lane; if you stay in it through the gore area, you must exit. It is a warning about lane assignment, not a command to cut across immediately. Check mirrors and the semi’s position, signal early, and adjust speed to merge into a safe gap behind or ahead of the truck rather than alongside it. Do not drift into the exit-only lane at the last second. If traffic and the semi prevent a safe move, accept the next exit rather than forcing a lane change; a missed exit is safer than a sideswipe.
3. Your fuel light is on. Should you take Exit 129 no matter what, or consider another option? Explain the tradeoff.
Read the worked answer
The fuel light changes the planning problem, but it does not justify an unsafe last-minute lane change. Exit 129 is close, and the indicated range may be enough, but the estimate has been dropping. If Exit 129 has services and you can move right safely, take it and refuel. If the gauge is falling faster or you cannot reach the exit-only lane safely, plan for the next exit with services rather than stopping on the shoulder unless it is a true emergency. Do not pass Exit 129 and then reverse or use the median. The decision should balance fuel margin, lane-change safety, and the next known service opportunity shown by guide signs.