Advisory Speed, Chevrons, and a Trailer on a Wet Mountain Road
You are northbound on a two-lane mountain highway north of Santa Fe at dusk in light rain. Posted speed is 55 mph. You are driving a pickup towing a 3,500-pound trailer. Ahead, a yellow diamond sign shows a left curve, with a rectangular plaque reading 25 MPH. Beyond it, a series of chevron signs points left around the bend. One mile before the curve you passed a yellow diamond deer-crossing sign. Visibility is about 300 feet, and the pavement is wet. A car ahead is maintaining a two-second gap from you. Your trailer brakes are working, but the trailer is not equipped with anti-lock brakes. You feel pressure from a tailgater behind you. You must choose a speed and lane position before entering the curve.
1. Is the 25 MPH plaque a speed limit you must obey, or advice? How should it affect your speed given the trailer and wet road?
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The 25 MPH plaque is an advisory speed, not a regulatory speed limit. It is posted because the curve geometry, superelevation, or sight distance makes 25 mph a reasonable maximum for typical conditions. That does not mean you may treat 55 mph as acceptable. With a 3,500-pound trailer, wet pavement, and limited visibility, your combination vehicle needs more distance to slow and is more likely to jackknife or push the tow vehicle wide. You should enter the curve at or below 25 mph, braking gently in a straight line before the curve rather than sharply inside it. The advisory speed is a warning benchmark; conditions can make an even lower speed necessary.
2. What do the chevron signs add that the curve warning sign does not? How should you use them?
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The curve warning sign tells you a curve is ahead; the chevrons show the actual alignment through the curve. They are placed along the outside of the bend to guide your steering and to make the curve visible at night or in rain. If you see several chevrons in sequence, the curve continues and may be sharper than it first appears. You should keep your vehicle aimed between the chevrons, avoid cutting the curve, and use them as a cue to maintain a steady, low speed. If the chevrons seem to disappear into darkness beyond your headlights, that is a signal to slow further, not to speed up to follow the tailgater.
3. The tailgater is close. What should you do about the two-second gap ahead and the deer-crossing sign?
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Do not speed up to satisfy the tailgater. Instead, increase your following distance ahead to at least four seconds, because the wet road and trailer lengthen stopping distance. Brake earlier and more gently so the tailgater has time to react. The deer-crossing sign means deer may move across the road in this area, especially at dusk; scan the shoulders and reduce speed before the curve. If the tailgater remains dangerously close, use a turnout or safe wide spot to let the driver pass, rather than letting pressure push you into the curve too fast.