Exit-Only Lane at Night: Fuel Range Against a No-Services Sign
Westbound on I-94 in southwestern North Dakota at 11:20 p.m., you have the cruise set at 80 mph in a posted 75 mph zone. The fuel gauge sits just above 1/8. The tank holds 26 gallons and the truck has been averaging about 13 mpg at this speed. You pass a green guide sign reading EXIT 61 - 1 MILE, with fuel and food logos, then a smaller white-on-green sign reading NO SERVICES NEXT 68 MILES. Beyond it, a yellow panel reading EXIT ONLY sits above the right lane, and the line separating the right lane from the through lane is solid white. A semi is in the right lane at your rear quarter panel. The next exit beyond Exit 61 is 68 miles ahead.
1. Work the fuel numbers. Can you legally and practically continue past Exit 61?
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One-eighth of 26 gallons is about 3.25 gallons. At 13 mpg that is roughly 42 miles of range - and that is the optimistic figure, because you are running 80 mph, which burns more than the 13 mpg average, and because you should never plan to run a tank dry (sediment pickup, fuel pump overheating, and no shoulder safety margin). Realistic usable range before you are walking is closer to 30–35 miles.
The NO SERVICES sign says the next 68 miles have no fuel. You cannot cover 68 miles on 42 miles of theoretical range. The decision is made for you: take Exit 61.
Notice that the green sign is information, not a command - the state does not require you to exit. But the sign exists precisely so a driver can do this arithmetic in time. Waiting to see whether the gauge is lying means committing to a 68-mile gap with a reserve that does not exist.
2. Explain what the green guide sign, the yellow EXIT ONLY panel, and the solid white line each require of you, and describe the maneuver given the semi at your rear quarter.
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Green means guidance and permission: the exit exists, services are there, and using it is your choice. Yellow means warning: EXIT ONLY tells you the right lane will leave the interstate, so continuing straight from that lane is not an option - the lane ends into the ramp. The solid white line is the edge of the through lane; crossing it is a lane-change violation and the line becomes the gore area that you may never drive across.
The semi at your rear quarter is the real constraint. You cannot simply drift right, and you must not brake hard in front of it. Sequence: signal early and hold it, let the semi either complete the pass or fall back, then change right across the solid line only where it is legal (before the line becomes the gore), and once established in the exit-only lane, decelerate on the ramp - exit ramps have advisory speeds posted, and 80 mph into a ramp at night is a departure-from-lane crash waiting to happen.
3. Suppose you realize too late and the gore area is already beside you. What are your legal options, and what is prohibited?
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Your option is the next exit, 68 miles on, and you manage the fuel risk by slowing to 60–65 mph, drafting nothing, and running the heater and lights on minimum. If the gauge reaches the low-fuel light before that, the correct move is to stop at the next safe place - a rest area or weigh station shown on a guide sign - and arrange fuel, not to continue gambling.
Prohibited: crossing the gore or the solid white line to reach the ramp, and emphatically backing up on the shoulder or the ramp. A vehicle in reverse on an interstate shoulder at 11:20 p.m. is invisible until it is a fatality. Crossing the gore is also an easy ticket, and the pavement there is often unpainted, uneven, and studded with sign posts.
The general principle the exam is testing: guide signs let you plan so that you never have to make an illegal recovery from a missed decision.