Laws for Slow-Moving Vehicle Signs

A vehicle traveling at a maximum speed of 25 miles per hour is considered a collision hazard, since faster cars that are trying to pass can cause head-on collisions. To keep the roadways safe, laws have been created regarding the proper use of slow moving vehicle emblems. These emblems act as a warning so drivers have enough time to slow down before reaching, or hitting, the slow-moving vehicle.

Who Can use a Slow Moving Vehicle Emblem?

According to the Ohio Revised Code, which is similar to many other state's vehicle codes for slow-moving vehicle signs, and the National Ag Safety Database, slow-moving vehicle or SMV emblems are restricted to use on:

  • Animal-pulled vehicles such as a horse and carriage
  • Farm machinery
  • Road construction machinery when it is not guarded by flag men or people working in a designated construction zone. 

States have their own definitions for farm machinery but generally, you're looking at machines used in planting, harvesting and caring for agricultural goods, including trailers that transport agricultural products to a storage area. When bearing the SMV emblem, these vehicles are prohibited from traveling more than 25-miles-per hour even if they are capable of reaching higher speeds.

Laws Regarding the Proper Placement of Signs

SMV emblems are a standard, red-orange fluorescent, equilateral triangle with a red reflective border. By law, they must measure a minimum of 13.8 inches across. In terms of placement, SMV emblems are to be mounted, point up, on the back of the vehicle as close to the center as possible. Proper mountings should be between two to six feet from the ground; they are not permitted to be placed higher than 10 feet from the ground.

The main thrust of SMV laws is that emblems must be visible from a distance of 500 feet. If one slow moving vehicle is pulling another, the emblem must be mounted on the rear vehicle. SMV emblems must comply with the standards agreed upon by the American Society of Agricultural Engineers. If they begin to fade, they must be replaced.

What To Do if You See a Slow Moving Vehicle

SMV emblems are issued for a reason, and that reason is it can be extremely hazardous to come up behind a slow moving vehicle at speed. Not only must the driver apply his brakes quickly, which can be a skid risk, but the horse of a horse-drawn carriage may be startled and behave erratically. Agricultural and construction vehicles are long and wide and may need additional space to turn.

The SMV emblem if your warning to be vigilant. When you see one, slow down and stay well back. Overtaking can be a difficult maneuver as you need to ensure that there is enough room on the road to pass a large vehicle. You should first drop back. Not only does this increase your ability to see the road ahead, it also ensures the driver of the slow-moving vehicle can see you in his mirrors. Don't attempt to pass unless you are absolutely sure that it is safe to do so.

When Not to Use an SMV Emblem

It is illegal to place an SMV emblem on a still object. For instance, they are not to be placed on mailboxes or used as markers for driveways. According to the National Ag Safety Database, caution signs, reflectors or reflective tape should be used on these objects instead. Many states also have laws prohibiting the placement of a slow moving vehicle emblem on a stationary vehicle that is being transported by another means of transportation on a highway. States have different laws so do check the specific restrictions in your state.

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