MUTCD W5-3a: ONE LANE BRIDGE and ONE LANE UNDERPASS Signs
The W5-3a sign is covered in Section 2C.19 of the Manual on Uniform Traffic Control Devices, 11th Edition. Below are the provisions from that section that describe when the sign is used and how it is placed.
What it means and when it is used
- Guidance · Recommended (should)A ONE LANE BRIDGE (W5-3) sign (see Figure 2C-6 ) should be used on two-way roadways in advance of any bridge or culvert: A. Having a roadway horizontal clearance of less than 16 feet, or B. Having a roadway horizontal clearance of less than 18 feet when commercial vehicles constitute a high proportion of the traffic, or C. Having a roadway horizontal clearance of 18 feet or less where the sight distance on the…
- Guidance · Recommended (should)Where these conditions exist for an underpass, a ONE LANE UNDERPASS (W5-3a) sign (see Figure 2C-6 ) should be used.
Where to read the rest
- Full text: MUTCD Section 2C.19: ONE LANE BRIDGE and ONE LANE UNDERPASS Signs
- Minimum sign sizes by roadway type are in the size section for this chapter: Section 2C.03
- Mounting height, lateral offset and retroreflectivity for any sign: MUTCD sign placement guide
Related signs in Section 2C.19
Source: Manual on Uniform Traffic Control Devices, 11th Edition (Federal Highway Administration, December 2023, public domain). Excerpts are shortened and shown out of context; read the full section before specifying a sign. Your state may still be operating under the 2009 edition or a state supplement. Official manual: mutcd.fhwa.dot.gov.