Traffic Signs to Restrict Trucks
Clear Communications Essential for Traffic and Structure Safety
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Municipalities must often restrict truck weights over weak roads or bridge structures. They must also warn truck drivers of low height underpasses. Exceeding either weight or height limitations can harm vehicles and drivers as well as roads and bridges. Truck drivers need clear information, especially those unfamiliar with local roads and their potential dangers. In addition to proper sign selection, agencies must place traffic signs so drivers can avoid a hazard. In addition, city and town governments often restrict trucks to satisfy citizens on certain roads. Traffic sign messages must be clear to enable enforcement. Sign combinations, such as those in picture 1, are confusing. The top sign prohibits all trucks. The sign below it restricts only those traveling through the designated street. This article will describe the Manual of Uniform Traffic Control Devices (MUTCD) traffic signs for restricting trucks, and their proper locations. The verbs "shall," "should," and "may" indicate respectively the mandatory, recommended, and optional rules. |
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Weight Restrictions
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The MUTCD provides many options to inform drivers of weight restrictions. These signs are intended to restrict all vehicles that exceed the specified weight.
The Weight Limit R12-1 sign indicates total vehicle weight restrictions. Where the restriction applies to axle weight, agencies may install the R12-2. The R12-3 sign restricts trucks by reference to empty weight in residential districts.
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The R12-4 sign describes multiple regulations of the type described above. Agencies can post multiple load limits with the R12-5 Weight Limit symbol sign. They can specify weights for any of the Weight Limit signs.
The MUTCD standard or mandatory rule for location is in advance of the applicable section of highway or of a structure. It recommends that the Weight Limit sign with an advisory distance ahead legend be placed at approach road intersections or other points where prohibited vehicles can detour or turn around.
Clearance Restrictions
Municipalities should install a W12-2 sign at the nearest intersecting road or wide point in the road at which a vehicle can detour or turn around. For an arch or other structure under which the clearance varies greatly, two or more signs should be used on the structure itself to give clearance information across the entire roadway.
Clearances should be evaluated periodically, particularly when resurfacing operations have occurred.
The
Low Clearance sign may be installed on or in advance of the structure. If placed
on the structure, it may be a rectangular shape (W12-2P) with the appropriate
legend.
Selective Exclusion Signs
The signs above restrict all vehicles of a given height or weight. The Selective Exclusion Signs described below also restrict all vehicles of the specified type.
Selective Exclusion signs notify road users that state or local laws exclude designated vehicles or pedestrians from particular roadways or facilities. Typical exclusion messages include:
The word message NO TRUCKS may be used as an alternate to the No Trucks (R5-2) symbol sign. Other Selective Exclusion signs are illustrated on page 2B-32 of the MUTCD. Selective Exclusion signs shall clearly indicate the type of traffic that is excluded. If an exclusion is governed by vehicle weight, agencies should install a Weight Limit Sign described above instead of a Selective Exclusion Sign.
Selective Exclusion signs should be placed on the right side of the roadway at an appropriate distance from the intersection so as to be clearly visible to all road users turning into the roadway that has the exclusion. The PEDESTRIANS PROHIBITED (R5-10c or R9-3a) sign should be installed so as to be clearly visible to pedestrians at a location where an alternative route is available.
Residential Street Restrictions
Some municipalities restrict trucks to satisfy residents on certain streets. The signs described above prohibit all trucks with specified characteristics. Even the R12-3 sign, which the MUTCD states may be used in residential areas, restricts all vehicles above a specific empty weight.
In many instances, however, residents' desires are ambiguous. For example, residents want trucks to provide needed services, but they don't want to see the same truck types passing through their neighborhood.
Certain word message signs can restrict trucks from residential streets except those that provide necessary services. MUTCD Section 1A.03 provides the following option: "Highway agencies may develop word message signs to notify road users of a situation that may not be readily apparent."
The bottom sign in Picture 1 is an appropriate word message sign. Placed with the R5-2 No Trucks sign, however, drivers receive two messages: (1) no trucks permitted or (2) only trucks with business on the designated street are permitted. Sign managers should install only the sign that clearly describes which trucks the city or town intends to restrict.
Word message sign locations should be the same as for other truck restriction signs. Weight Restriction Sign location shall be in advance of the applicable section of highway or structure. It recommends that the sign with an advisory distance ahead legend be placed at approach road intersections or other points where prohibited vehicles can detour or turn around.
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