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Driving safety guide · Michigan City Ford · Michigan City, IN
Slippery When Wet and Other Road Surface Signs
The Slippery When Wet sign is one of a family of warning signs about the road surface itself. Here is what the federal Manual on Uniform Traffic Control Devices (MUTCD) says each of these signs warns about and where they go.
W8-5Slippery When Wet: unexpected slippery conditions
ICE, WHEN WETplaques that may say why the road might be slippery
3 inchesthe line between a LOW SHOULDER and a Shoulder Drop Off sign
36 x 36 inSlippery When Wet sign size on multi-lane conventional roads and expressways
The short answer
The Slippery When Wet (W8-5) sign may be used to warn of unexpected slippery conditions, and a plaque such as ICE, WHEN WET, STEEL DECK or EXCESS OIL may say why. Related surface signs warn of loose gravel, a rough road, uneven lanes, a bridge that ices before the road, fallen rocks, bumps and dips, the end of the pavement, and soft, low or missing shoulders. When used, surface condition signs such as Slippery When Wet should be placed before the affected section of road.
Warning sign basics
Shape and color: unless the MUTCD says otherwise for a specific sign, warning signs are diamond-shaped with a black legend and border on a yellow background.
Sizes: the MUTCD lists the Slippery When Wet sign at 30 x 30 inches for single-lane conventional roads, 36 x 36 inches for multi-lane conventional roads and expressways, and 48 x 48 inches for freeways and the oversized version. Diamond-shaped warning signs facing traffic on multi-lane conventional roads shall be at least 36 x 36 inches.
From the Manual on Uniform Traffic Control Devices (MUTCD), 11th Edition with Revision 1, Section 2C.02 and Table 2C-1, read November 4, 2026.
The Slippery When Wet sign (W8-5)
What it warns of: the Slippery When Wet sign may be used to warn of unexpected slippery conditions.
Plaques: supplemental plaques with legends such as ICE, WHEN WET, STEEL DECK or EXCESS OIL may be used with it to show why the slippery conditions might be present.
Where it goes: when used, surface condition signs should be placed in advance of the beginning of the affected section, and more signs should be placed at intervals along the road where the condition continues.
For what to do if your tires lose grip on a wet road, see our guide to hydroplaning.
From the Manual on Uniform Traffic Control Devices (MUTCD), 11th Edition with Revision 1, Section 2C.30, read November 4, 2026. See MUTCD Table 2C-3 for advance placement guidance.
Other surface condition signs
The MUTCD groups these signs with Slippery When Wet:
| Sign | What it warns of |
|---|---|
| LOOSE GRAVEL (W8-7) | May be used to warn of loose gravel on the roadway surface. |
| ROUGH ROAD (W8-8) | May be used to warn of a rough roadway surface. |
| UNEVEN LANES (W8-11) | May be used to warn of a difference in elevation between travel lanes. |
| BRIDGE ICES BEFORE ROAD (W8-13) | May be used before bridges to advise drivers of winter weather conditions. It may be removed or covered in seasons when its message is not relevant. |
| FALLEN ROCKS (W8-14) | May be used before an area next to a hillside, mountain or cliff where rocks frequently fall onto the roadway. |
From the Manual on Uniform Traffic Control Devices (MUTCD), 11th Edition with Revision 1, Section 2C.30, read November 4, 2026. For icy roads, see our guide to driving on black ice.
Bumps, dips and speed humps
BUMP (W8-1) and DIP (W8-2): should be used in advance of a sharp rise or depression in the profile of the road. An Advisory Speed plaque may be added.
Hidden dips: the DIP sign should not be used before a short stretch of depressed road that might momentarily hide a vehicle. Where center line striping is provided on a two-lane or three-lane road, that kind of stretch should be treated as a no-passing zone.
SPEED HUMP (W17-1): should be used in advance of a raised section of roadway designed to limit the speed of traffic, and should be supplemented by an Advisory Speed plaque. The legend SPEED BUMP may be used instead; the MUTCD notes the two terms are interchangeable for signing purposes.
From the Manual on Uniform Traffic Control Devices (MUTCD), 11th Edition with Revision 1, Sections 2C.26 and 2C.27, read November 4, 2026.
Pavement and shoulder signs
These signs warn about the edge of the road and the end of the pavement:
| Sign | What it warns of |
|---|---|
| PAVEMENT ENDS (W8-3) | Should be used where a paved surface changes to a gravel treated surface or an earth road surface. An Advisory Speed plaque may be added. |
| SOFT SHOULDER (W8-4) | May be used to warn of a soft shoulder. |
| LOW SHOULDER (W8-9) | May be used where the shoulder is 3 inches or less lower than the travel lane. |
| Shoulder Drop Off (W8-17) | Should be used where an unprotected drop-off next to the travel lane is more than 3 inches deep for a significant continuous length, based on engineering judgment. A SHOULDER DROP-OFF plaque may be mounted below it. |
| NO SHOULDER (W8-23) and SHOULDER ENDS (W8-25) | May be used to warn that there is no shoulder along a section of road, or that a shoulder is ending. |
From the Manual on Uniform Traffic Control Devices (MUTCD), 11th Edition with Revision 1, Sections 2C.28 and 2C.29, read November 4, 2026. Where a shoulder condition continues, additional shoulder signs should be placed at intervals along the road.
Signs for motorcyclists
GROOVED PAVEMENT (W8-15): may be used where the pavement is grooved or textured instead of smooth, such as a grooved skid resistance treatment on a curve or a brick surface. TEXTURED PAVEMENT or BRICK PAVEMENT may be used as the legend.
METAL BRIDGE DECK (W8-16): may be used where a bridge or part of a bridge has a metal or grated surface.
Motorcycle plaque (W8-15aP): may be mounted with either sign when the warning is meant mainly for motorcyclists. The MUTCD notes that Slippery When Wet, LOOSE GRAVEL and ROUGH ROAD signs can also help motorcyclists.
From the Manual on Uniform Traffic Control Devices (MUTCD), 11th Edition with Revision 1, Section 2C.31, read November 4, 2026.
Keep your tires and brakes ready for slippery roads
The Works® at Michigan City Ford includes a synthetic blend oil change, tire rotation and pressure check, brake inspection, Multi-Point Inspection, fluid top-off, battery test, and a filter, belts and hoses check.
Schedule service online and see our service specials first. Michigan City Ford is at 3930 Franklin St. in Michigan City. Get directions.
Michigan City Ford service hours
| Days | Hours |
|---|---|
| Mon-Fri | 7:30 a.m.-5:30 p.m. |
| Sat | 8 a.m.-3 p.m. |
| Sun | closed |
From Michigan City Ford's website, November 4, 2026. Holiday hours can differ.
Slippery When Wet and road surface signs FAQ
What does a Slippery When Wet sign mean?
Under the MUTCD, the Slippery When Wet (W8-5) sign may be used to warn of unexpected slippery conditions. A supplemental plaque used with it, with a legend such as ICE, WHEN WET, STEEL DECK or EXCESS OIL, may show why the road might be slippery.
What does the Slippery When Wet sign look like?
It is a warning sign, so unless the MUTCD says otherwise it is diamond-shaped with a black legend and border on a yellow background. The MUTCD lists it at 30 x 30 inches on single-lane conventional roads and 36 x 36 inches on multi-lane conventional roads and expressways, with 48 x 48 inches for freeways and the oversized version.
What does a LOOSE GRAVEL sign mean?
The LOOSE GRAVEL (W8-7) sign may be used to warn of loose gravel on the road surface.
What does UNEVEN LANES mean?
An UNEVEN LANES (W8-11) sign may be used to warn of a difference in elevation between travel lanes.
Why is there a BRIDGE ICES BEFORE ROAD sign?
The BRIDGE ICES BEFORE ROAD (W8-13) sign may be used before bridges to advise drivers of winter weather conditions. The MUTCD allows it to be removed or covered in seasons when its message is not relevant.
What is the difference between a BUMP sign and a SPEED HUMP sign?
A BUMP (W8-1) sign should be used before a sharp rise in the profile of the road. A SPEED HUMP (W17-1) sign should be used before a raised section built to limit the speed of traffic, and the legend SPEED BUMP may be used instead. The MUTCD notes that for signing purposes the terms speed hump and speed bump are interchangeable.
What is the difference between LOW SHOULDER and Shoulder Drop Off?
The LOW SHOULDER (W8-9) sign may be used where the shoulder is 3 inches or less lower than the travel lane. The Shoulder Drop Off (W8-17) sign should be used where an unprotected drop-off next to the travel lane is more than 3 inches deep for a significant continuous length.
What does The Works at Michigan City Ford include?
The Works® at Michigan City Ford includes a synthetic blend oil change, tire rotation and pressure check, brake inspection, Multi-Point Inspection, fluid top-off, battery test, and a filter, belts and hoses check.
Book a routine checkup
Book The Works, which includes a brake inspection, tire rotation and pressure check, and battery test, at Michigan City Ford.
Sources
Sign descriptions are from the Federal Highway Administration's Manual on Uniform Traffic Control Devices, 11th Edition with Revision 1 (Revision 1 dated December 2025), read November 4, 2026. This page is a plain-language summary of national standards, not legal advice; state law sets the rules of the road where you drive. Service details, address and hours are from Michigan City Ford's own website, checked the same day. Photo is illustrative.
- Manual on Uniform Traffic Control Devices (MUTCD), 11th Edition with Revision 1 (Sections 2C.02 and 2C.26 to 2C.31; Table 2C-1), Federal Highway Administration, Revision 1 dated December 2025 (PDF updated February 12, 2026), read November 4, 2026
- General service: The Works, Michigan City Ford, November 4, 2026
- Address and service hours (structured data), Michigan City Ford, November 4, 2026