Utility Poles: Appendix 4

Illustration of Washington State DOT's Above Ground Utility Object Collision Reduction Program

WSDOT in cooperation with the Utility companies in the State has developed a unique program to systematically reduce collisions involving utility poles and other utility objects. This appendix gives a summary of the important elements of the program.

Background and History

The WSDOT program is focused on state maintained highways, and hence, primarily a rural program that covers approximately 6000 miles of highway containing utility objects. The program initially started in 1985, and utilities were required to relocate or mitigate utility objects within one year after removal of a franchise agreement (1). This created excessively large expenses for the utilities within a short period of time. To address this issue, in 1989, WSDOT formed a committee that included WSDOT staff and representatives from the Utility organizations, and developed a collaborative program. In this program, WSDOT and the Utilities work together to classify existing utility objects into three categories: location I, location II, and location III, which were defined based on the calculation of a control zone. In general, utility objects in locations I and II are closer to the roadway, and can result in more collisions than utility objects in location III. In general, the overall objective is to move more utility objects from locations I and II, to location III. Further details about the program including definitions are provided in the following paragraphs.

Control Zone

The Control Zone is a calculated distance located within the highway right-of-way in which the placement of utility objects is controlled. It is measured in feet normal to the highway, beginning at the edge of the traveled way and extending outward perpendicular to the traveled way. It varies with speed, traffic, and roadway slope, and can be determined using the Control Zone Distance Table (Table A.1) and some additional criteria (2, page 3-8). In general, the control zone distance increases with increase with ADT and posted speed limits.

Location I Objects

Utility objects located within the control zone in the following areas are normally considered Location I objects unless classified as a Location III object (2, page 3-5):

  • Outside of horizontal curves where advisory signed speeds for the curve are 15 or more mph below the posted speed limit of that section of highway
  • Within the turn radius area of public grade intersections
  • Where a barrier, embankment, rock outcropping, ditch, or other roadside feature is likely to direct a vehicle into a utility object
  • Closer than 5 feet horizontal beyond the edge of the usable shoulder

Table A.1: Control zone distance table.

Source: Anderson (2)

It is estimated that approximately 20 percent of the utility objects in Washington State are location 1 objects (1).

Location II Objects

This includes all utility objects located within the Control Zone and not classified as Location I or Location III objects. It is estimated that approximately 32 percent of the utility objects in Washington State belong to this category (1).

Location III Objects

These include:

  • Utility objects located outside the control zone
  • Utility objects within the control zone that are mitigated by an alternate countermeasure, such as locating on private easement outside the ROW, putting utility lines underground, shielding utility objects in some way, or designing breakway utility objects (2, 3).
  • Location II objects that have been classified as Location III using the AASHTO cost-effectiveness methodology contained in the Roadside Design Guide (4).

It is estimated that approximately 48 percent of utility objects in Washington State are Location III objects (1).

Annual Mitigation Targets

The number of utility's existing control zone objects to be relocated or mitigated in a given year is established by WSDOT and the utility, based on the following annual mitigation target (AMT) formula (1, 2):

AMT = [(M x 5280) / N] x (Z) / Y

Where,

M = the number of miles of utility owned above ground facilities located within highway right of way (this is multiplied by 5280 to convert to feet)

N = the utility's average line span length in feet

Z = percent of objects owned by utility that are estimated to be in Location I or II

Y = number of years, 50 maximum, for compliance

According to the guidelines, a utility has to make every effort to achieve its AMT. If a utility does not achieve its AMT in a particular year, the number of objects that are to be relocated or mitigated in the following year shall be increased so that the average number of objects that are relocated or mitigated over time equals its AMT. If a utility exceeds its AMT in a particular year, the utility may reduce the number of objects that are to be relocated or mitigated in the following year.

Although the AMT may be an effective way to reduce the number of utility objects in the roadside, it may also be useful to monitor / estimate the number of accidents that are being prevented every year due to the program (5).

Application of the Program

Under the guidelines, all new utility objects will be constructed outside the control zone unless they are covered by a variance (discussed below), or are location III objects. In addition, utilities are responsible for the systematic treatment of existing utility pole objects that are located in the control zone. A utility can meet its AMT by addressing existing objects during WSDOT highway projects, utility reconstruction, and through a program of systematic studies of its objects (2). If it is determined through an engineering analysis, that a Location I object cannot be moved to Location III or mitigated, a variance may be considered.

Variance

The variance clause is included in order to address conditions that may arise making it impractical to comply with the maximum control zone. Variances from such compliance could be allowed when justified by suitable utility engineering studies considering traffic safety. Examples of conditions rendering compliance impractical include:

  • WSDOT right of way that is not adequate to accommodate utility objects outside the control zone.
  • Segments of utility facilities that, due to terrain or other features, do not warrant being located in full compliance with the maximum control zone.

Results of the Program

It is estimated that the program has treated about 3200 poles so far (5). Washington has also reported a significant reduction in the number utility pole accidents in the last 10 years after the implementation of this program (Figure A.1). Statewide, the number of utility pole accidents has reduced from approximately 440 in 1990 to approximately 300 in 1999.


Figure A.1: Statewide utility pole accidents.
Source: Anderson (2)

References

  1. “The influence of utilities on roadside safety”, Prepared by the Utility Safety Task Group, Utilities Committee (A2A07), Washington, D.C., April 2002.
  2. R. Anderson, “Control zone guidelines - utilities: above ground utility object collision reduction”, Washington State Department of Transportation, April 2002.
  3. R. Anderson, “Washington's Initiative”, In Utility Safety: Mobilized for Action and State, City, and Utility Initiatives in Roadside Safety, Transportation Research E-Circular # E-C030, April 2001.
  4. “Roadside design guide”, American Association of State Highway and Transportation Officials, January 1996.
  5. “Utility pole breakout meeting minutes”, For NCHRP project 17-18(3), May 2002.