Advisory Speed, Rain, and a Flooded Dip on Route 17
At 9:15 p.m. you are southbound on Route 17, Cross Island Road, descending the long grade toward Pago Bay in steady rain. The posted limit is 35 mph. A pickup is tailgating about one car length behind you. In sequence you pass a yellow diamond showing a winding-road symbol with a 25 MPH advisory plaque, then a yellow diamond reading SLIPPERY WHEN WET, then a yellow diamond that shows a car above waves with the legend FLOOD AREA. At the bottom of the grade the road dips; water is sheet-flowing across both lanes, and a sedan ahead has stopped with its hazard lights on. There are no barricades, no depth gauge, and no officer on scene. Your passenger says the 25 MPH plaque is just a suggestion and that you should speed up to put distance between you and the tailgater.
1. What is the status of the 25 MPH advisory plaque compared with the 35 mph limit, and how should the rain and the tailgater change your speed choice?
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Both parts of the passenger's statement need correcting, and the wrong half is the dangerous one.
- The 25 MPH plaque is advisory, not a speed limit. Yellow diamonds warn; they do not create an enforceable maximum the way a white speed-limit sign does. The 35 mph limit still governs the approach.
- But a limit is a ceiling for ideal conditions, not a target. The winding-road and SLIPPERY WHEN WET signs are telling you the curve was designed for roughly 25 mph in the dry; in rain, at night, with glare on wet asphalt, your safe speed is lower again.
So calling it a suggestion is the wrong frame: it is the sign author's estimate of a safe dry speed, and the weather has made that estimate optimistic. As for the tailgater, speeding up does not solve it - you would simply reach the flooded dip faster. Hold a steady lower speed and let the pickup pass at the first safe pullout.
2. Water is flowing across both lanes at the dip and the sedan ahead has stopped with hazards on. How do you decide whether to drive through?
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Turn around; do not enter. The reasoning is not about confidence but about what you cannot see:
- Depth is unknown and so is the surface beneath. At night, sheet flow hides potholes, undermined pavement, and the drop at the shoulder edge.
- Moving water is the hazard, not standing water. Roughly a foot of moving water can float or shove most passenger cars, and less can stall an engine or sweep a small vehicle off the roadway.
- The sedan's hazard lights tell you that one driver stopped. They do not tell you the water is passable - that driver may have stopped for exactly the reason you should.
The correct action is to back out or make a U-turn where safe and take an alternate route, warning oncoming drivers only if you can do so without standing in the roadway. A barricade or ROAD CLOSED sign would settle the question; its absence does not make the crossing legal or safe.