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FHWA Home / Safety / Geometric Design / Publications / Mitigation Strategies For Design Exceptions

12. Lateral Offset to Obstruction

As discussed in Chapter 3, a lateral offset to obstruction is not the same as the clear zone.  A lateral offset, by definition, deals with objects so close to the roadway that there may be adverse impacts to the operation of the highway.  Some examples of these objects include walls, barriers, bridge piers, sign and signal supports, trees, and utility poles.  The clear zone is a clear recovery area, free of rigid obstacles and steep slopes, which serves a safety function.

Target areas:  Any highway with roadside obstacles near the traveled lanes&mdash most commonly, urban arterials.

Strategy:  Delineate roadside obstacles.

Assuming an object cannot be removed or relocated, the primary mitigation strategy is to make the objects highly visible to drivers.  Delineation with reflectors or reflective sheeting (Figures 68 and 69) is one method to make the objects more visible, particularly at night.  Another strategy to consider is lighting.  In addition to making roadside objects more visible, lighting has many other benefits in urban areas where design exceptions for lateral offset are most common&mdash from public safety benefits to improved pedestrian safety.

Figure 68.  Reflective sheeting on utility poles.

FIGURE 68

Reflective sheeting on utility poles.

Figure 68 is a photo showing a utility pole on the side of a road with a band of bright yellow reflective material wrapped around the pole, approximately 4 feet off the ground.

Figure 69.  Reflective sheeting on utility poles.

FIGURE 69

Reflective sheeting on utility poles.

Figure 69 is a photo showing a close-up view of a utility pole with a band of white reflective material encircling the pole about 4 feet off the ground.  The band is wrapped around a square of bright yellow reflective material in place behind it.

 

Target areas:  Any highway with roadside obstacles near the traveled lanes&mdash most commonly, urban arterials.

Strategy:  Narrow selected cross-sectional elements to provide additional offset to the obstruction.

On urban arterials with more than two lanes, another strategy to consider is distributing the available cross-sectional width to provide additional offset to the obstruction.  For example, through lanes, turn lanes, or medians could be narrowed slightly in order to provide additional offset or additional space for on-street parking.  With this strategy, care must be taken to ensure that any operational benefits gained in the outside lanes are not lost to poorer performance on the inside lanes.  Each site will have unique characteristics that need to be evaluated before determining an optimal distribution of the cross section&mdash traffic volumes, traffic composition, the available cross-sectional width, speed studies, and offset distance to the obstruction.

Target areas:  Any highway with roadside obstacles near the traveled lanes&mdash most commonly, urban arterials.

Strategy:  Enhanced pavement markings.

Another mitigation strategy for lateral offset is clear delineation of the lane lines.  See the Lane and Shoulder Width section for information on enhanced pavement markings.


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Page last modified on April 1, 2019
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