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Chapter 10
Roadside Management and Maintenance: Beyond Vegetation
10.9. Maintenance of Shoulders and Roadway Appurtenances

Areas adjacent to surfaced and unsurfaced road shoulders require maintenance to prevent the loss of lateral support, to prevent the deterioration or failure of the road edge and to maintain roadside drainage patterns, and to prevent excessive sedimentation and pollution from applied abrasives. Potential pollutant sources may include disturbed soil, leaks, and wind erosion which can then release pollutants like sediment, fuel, hydraulic fluid and oil.

  • Water applied during sweeping operations should be controlled to prevent unpermitted non-stormwater discharges.
  • Use applicable water quality management practices such as illicit connection/illicit discharge reporting and removal, scheduling and planning, illegal spill discharge control, vehicle and equipment fueling, vehicle and equipment maintenance, compaction, material use, spill prevention and control, sweeping and vacuuming, and water conservation practices. Subtasks include equipment operation, grading, rolling, import and fill, and post-sweeping. [N]


10.9.1 Cleaning/Sweeping of Shoulders
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Sweeping operations remove litter and debris from the traveled way and shoulder to reduce traffic hazards and improve aesthetics. Subtasks associated with highway sweeping operations include operation of support vehicles, sweeper operation, stockpile management, and material disposal. Potential pollutant sources include spills, leaks, and stockpiles.

The following environmental stewardship practices are utilized on the municipal level and may be used by state DOTs: [N]

  • Care should be taken to minimize dust as much as possible.
  • Water applied during sweeping operations should be controlled to prevent unpermitted non-stormwater discharges.
  • Stormwater quality control measures should be employed, including illicit connection/illicit discharge reporting and removal, scheduling and planning, safer alternative products, illegal spill discharge control, vehicle and equipment fueling, vehicle and equipment maintenance, solid waste management, liquid waste management, sweeping and vacuuming and water conservation practices. [N]
  • Equipment should be in good working order and contain filters and/or other controls as feasible.
  • Avoid wet cleaning or flushing of street, and utilize dry methods where possible.
  • Consider increasing sweeping frequency based on factors such as traffic volume, land use, field observations of sediment and trash accumulation, proximity to water courses, etc. For example:
    • Increase the sweeping frequency for streets with high pollutant loadings, especially in high traffic and industrial areas.
    • Increase the sweeping frequency just before the wet season to remove sediments accumulated during the summer.
    • Increase the sweeping frequency for streets in special problem areas such as special events, high litter or erosion zones.
  • Maintain cleaning equipment in good working condition and purchase replacement equipment as needed. Old sweepers should be replaced with new technologically advanced sweepers (preferably regenerative air sweepers) that maximize pollutant removal.
  • Operate sweepers at manufacturer requested optimal speed levels to increase effectiveness.
  • To increase sweeping effectiveness consider the following:
    • Institute a parking policy to restrict parking in problematic areas during periods of street sweeping.
    • Post permanent street sweeping signs in problematic areas; use temporary signs if installation of permanent signs is not possible.
    • Develop and distribute flyers notifying residents of street sweeping schedules.
  • Regularly inspect vehicles and equipment for leaks, and repair immediately.
  • If available use vacuum or regenerative air sweepers in the high sediment and trash areas (typically industrial/commercial).
  • Keep accurate logs of the number of curb-miles swept and the amount of waste collected.
  • Dispose of street sweeping debris and dirt at a landfill.
  • Do not store swept material along the side of the street or near a storm drain inlet.
  • Keep debris storage to a minimum during the wet season or make sure debris piles are contained (e.g. by berming the area) or covered (e.g. with tarps or permanent covers).


10.9.2 Shoulder Grading, Widening, Blading, or Rebuilding
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Shoulder Blading/Rebuilding includes shoulder blading and rebuilding to correct rutting and buildup of materials, to remove weeds, for safety, and to maintain proper drainage. This activity can be similar to ditching, and has similar stewardship practices to avoid and minimize environmental impacts. Environmental stewardship practices include the following recommendations: [N]

  • When conducting shoulder maintenance activities in areas with narrow shoulders or steep slopes, inspect the area and/or consult with environmental support staff to determine if there are wetlands, waterbodies, or sensitive cultural resources (such as historic buildings or parkways) in the area.
  • Where appropriate, permanently stabilize disturbed soils using BMPs (seeding, plants, etc.).
  • Evaluate sensitive areas for alternatives to blading, such as berming, curbing or paving shoulders.
  • Where practicable, evaluate the width of the blading activity and if appropriate, modify the width to minimize disturbance of vegetation.
  • Where possible, blade in dry weather, but while moisture is still present in soil and aggregate (to minimize dust). Special precautions may be necessary in PM-10 air quality non-attainment areas.
  • Where appropriate, permanently stabilize disturbed soils using BMPs (seeding, plants, etc.).
  • Contact environmental support staff before placing excess material to widen the shoulders or smooth out the slopes,
  • Install check dams to protect sensitive resources, when appropriate.
  • Incorporate this activity into local IVM plans to consider and minimize impacts of this activity on streams.
Dust Abatement for Blading and Shaping Gravel Surfaces
Dust abatement involves application of a dust palliative to non-paved road surfaces to temporarily stabilize surface soils, leading to a reduction of dust during the dry season. Palliatives are typically applied in liquid form and could include magnesium chloride, calcium chloride, emulsified asphalts, or lignon sulfonates. Environmental stewardship practices include the following recommendations: [N]
  • During preparation for application of dust palliatives, construct gravel berms at the low shoulders of the roadway to inhibit liquid palliatives from entering surface waters.
  • Do not apply dust palliatives during rain.
  • Do not apply materials in a manner that is not detrimental to either water or vegetation.
  • Carry adequate spill protection, such as kitty litter, shovels, etc.
  • Use environmentally sensitive cleaning agents.
  • Dispose of excess materials at appropriate sites.


10.9.3 Guardrail Maintenance and Replacement
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Guardrail replacement involves repair and replacement of existing guardrail sections and cleaning of accumulated material from under the guardrail. To avoid and minimize environmental impacts:

  • Cleaning under the guardrail in or near riparian areas should consider the pickup and removal of material. Material should not be pushed down slope.
  • Consider using large capacity vacuum trucks, to clean abrasives from bridge decks and under guardrails in sensitive areas.
  • Consider new technologies in guardrails such as wire rope safety fence (WRSF) can both improve safety, hasten repair times, and reduce material usage and disposal issues. Furthermore, during repair, guardrail usually requires heavy equipment and a lane closure greatly slowing traffic (fuel and emissions). WRSF can be repaired with one man in a pickup without a lane closure in normally less than 30 minutes. The design allows small animals to pass through and can minimize snow accumulation. WRSF can also blend into surroundings and help minimize the approach slope needed; concrete barrier and guardrail require 10 to 1 approach slopes while WRSF can have 6 to 1 slopes, adding a land consumption benefit in some cases. [N]
  • In unstable situations, protect areas downslope from guardrail replacement with erosion control measures (silt fences and other appropriate devices) where appropriate to minimize additional sediment loadings into aquatic systems.


10.9.4 Attenuator Maintenance
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Attenuator Maintenance involves service, repair, replacement, and realignment of damaged attenuators (physical systems that are strategically placed along exit ramps, bridge abutments, etc. to minimize impacts and cushion vehicles). Following impact, attenuators compact, releasing fluid (often ethylene glycol) which can flow directly to drainage systems. Practices to avoid and minimize such impacts include: [N]

  • Use non-chemical systems when installing new attenuators.
  • When replacing attenuators, install those devices found to be the most environmentally sound.
  • Use absorbent dams or diapers around attenuators during repair or maintenance.
  • Identify and close inlets (if appropriate and can be done safely) during attenuator maintenance.


10.9.5 Luminaire Replacement to Reduce Light Pollution and Increase Energy Efficiency
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Roadway lighting is an important part of a highway system. It contributes to a safe environment and facilitates traffic flow for the traveling public during evening or nighttime driving. Lighting shows drivers changes in direction, obstacles, and roadway surface conditions. Exterior lighting may also have a significant impact on economic development. At present, roadway lighting standards are based almost exclusively on traffic safety.

The impact of roadway lighting practices on the surrounding environment is of increasing concern to the public and DOTs, out of concern for impacts on wildlife as well as energy efficiency and cost. Light pollution is an unwanted consequence of outdoor lighting and includes such effects as skyglow, light trespass, and glare. " Sky glow" is a brightening of the night sky caused by natural and human-made factors. " Glare" is an objectionable brightness or reflection of light and a driving hazard especially bothersome for older drivers. "Light trespass" is the actual light that falls off the right-of-way and can be measured and quantified. In fact, many professional lighting designers have been obliged to go out at night and take measurements of the light that is falling off the right-of-way and onto a concerned citizen's property.

Cities and states in some cases have responded with lighting ordinances and requirements regarding certain types of fixtures, minimum and maximum lighting levels, lumen/acre limits, and eliminating lighting in some cases. Legislation has been adopted in Arizona, California, Connecticut, Colorado, Maine, New Mexico, Texas, Georgia, and New Jersey. Such legislation has been proposed or introduced in New York, Iowa, Massachusetts, Michigan, New Hampshire, Maryland, Pennsylvania, Rhode Island, Virginia, and Wyoming. Environmental impacts of lighting are of increasing concern to biologists and members of the public concerned about wildlife as well. These issues are described in greater detail in the Design section on Lighting Control and Minimization, section 3.14. which also includes sections on Common Lighting Approaches and Deciding How Much Light Is Enough; Practices in Assessing Lighting Needs; Comparison of Lighting Sources, Issues, and Costs; and Research to Improve Lighting Practices.

Light Minimization and Energy Efficiency Practices

  • Realign the fixture (change angle of mounting arm or rotate fixture head) so the source of light is not directly visible outside the ROW.
  • Apply a shield to a drop globe fixture.
  • Change an open bottom or drop globe fixture to a cutoff fixture.
  • Apply a shield to a cutoff fixture.
  • Reduce the mounting height of the fixture.
  • Reduce the lamp wattage.
  • Change the lamp socket position in the fixture to compress the lighting footprint.
  • Change to a fixture with a different type of reflector providing a more favorable lighting footprint.
  • In addition to other shielding and light reduction measures: Install a flat 2422 acrylic amber lens in a cutoff fixture with an HPS lamp of 70 watts or less (e.g., GELS 70W M250).
  • Turn the light off
  • Remove the fixture.
  • Relocate the fixture to block light from extending to sensitive resources.
  • Change to an LPS fixture (if the light is customer-owned).
  • Create a vegetated berm/buffer or other light shield between the roadway and the sensitive resource.

Electric utilities can generally provide the following options:

  • Seasonally turn the lights off,
  • Relocate or redirect the light fixture,
  • Change a drop globe fixture to a cutoff style fixture,
  • Remove the fixture,
  • Lower mounting height,
  • Reduce wattage,
  • Selectively install amber-colored filtering lenses (on cutoff fixtures of 70-watts or less and only in addition to other modifications), and
  • Install a light shield.

An overview of roadway lighting fixtures is available at the MetroLux Lighting website. [N]

Oregon DOT Illumination Reduction Practices

Oregon DOT (ODOT) involved all District and Regional Managers in response to possible energy shortages in the Pacific Northwest and directives from the Governor's office that all state agencies review power usage and develop conservation measures. Specifically, ODOT considered reducing highway illumination as a temporary measure, and undertook case studies to assess any differences that occurred with lighting reductions.

Region Traffic Engineers and District Maintenance staff worked together to determine specific luminaries to be turned off. The Traffic Management Section assisted in reviewing specific requests to assure the state continued to meet AASHTO standards for lighting on a statewide basis. In addition, ODOT's Traffic Engineering Services Unit conducted a comprehensive crash analysis, including a field review during both dark and dark/wet conditions, of the freeways in the Portland metro area. The crash analysis indicated no significant difference in the ratio of night-to-day crash rates by lighting condition. In fact, in most sections the night crash rate was substantially lower than the day crash rates. As a result of their research, ODOT developed the following guidelines for reducing illumination that may be utilized as practices for consideration by other state DOTs.

Lineal Lighting

ODOT's practices specified that lineal lighting along freeways and freeway-like facilities could be turned off unless the facility has the following characteristics:

  • Inadequate outside and median shoulders.
  • Vertical or horizontal alignments such that illumination may be beneficial to driver safety.
  • A crash analysis indicates that the night-to-day crash rate ratio is greater than 1.0
  • Section of highway has high levels of pedestrian and/or bicycle activities during times of darkness.
  • Sections where there are three or more successive fully-illuminated interchanges located with an average spacing of one mile or less between successive interchanges: (Note: This exception does not apply if the interchanges are partially illuminated. That is, if interchanges are partially illuminated, lineal lighting should be turned off regardless of spacing.)
  • Pavement markings and delineation should be in good condition when deciding to turn off lineal lighting. Durable striping is desirable.
  • Under certain designs (such as narrow median widths) it may be possible to reduce the lighting to only one side of the highway.
Interchange Lighting
  • Full interchange lighting should be reduced to partial interchange lighting unless the interchange has the following characteristics:
  • Ramp and/or interchange alignment and grade is complex or unusual.
  • Interchange area has high levels of pedestrian and/or bicycle activities during times of darkness.
  • Interchange that contains important decision point(s) and/or existing roadside hazard areas that would not be covered with partial illumination.
General Guidelines in Considering Luminaires to Turn Off
  • On Ramps - Standard of three continuous poles as a group on gore and merging sections minimum coverage is 150 meter (500 feet). Ramps with high truck traffic and/or longer acceleration lanes may need more coverage.
  • Off Ramps - Standard of three continuous poles as a group for gore (decision making point) including a ‘pull through' light. Highway alignment may require four poles to make a group.
  • Ramp Terminals - Standard of two poles on opposite corners of the intersection. At a rural intersection with a two-lane facility without a designated crosswalk, one pole at the intersection may be sufficient.
  • Underdeck Illumination - Should be turned off if no pedestrian and/or bicycle activity is expected and there is no current safety problem.

ODOT's illumination reductions were implemented as a temporary measure as a means to reduce energy consumption; however, the agency is considering permanent reductions if safety is not impacted. Assessment of reduced lighting is continuing. Changes from whole to partial interchange lighting at the entry and top of ramp and reductions in high tower illumination were the most common changes. Meanwhile ODOT produced a Traffic Lighting Design Manual in January 2003, which implements some lighting reductions, including a study on whether light removal would be possible.


10.9.6 Use of Light-Emitting Diode (LED) Traffic Signals to Reduce Energy Usage
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The California Department of Transportation (Caltrans) reduced agency-wide energy consumption by 21 percent in response to threats of rolling blackouts in 2001. More energy-efficient facilities such as the new building in downtown Oakland are one source of savings. Another is the award-winning light-emitting diode (LED) traffic signal upgrade effort, which, when complete, will reduce signal grid demands by 92 percent. Lighting plans can make better use of lights, conserve energy and make roadways safer by reducing the number of poles and fixtures. The department also contracted with a private company to conduct energy audits and implement efficiencies under a savings-sharing system. After examining other areas, such as bridge and tunnel lighting, bulk energy procurement and roadway sign lighting, Caltrans has realized about $181 million over 10 years in savings. [N]


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Continue to Section 10.10 »
Table of Contents
Chapter 10
Roadside Management and Maintenance: Beyond Vegetation
10.1 Environmental Enhancement Practices and Partnership Efforts
10.2 Protection of Historic and Other Cultural Resources
10.3 Maintenance in Wetlands
10.4 Maintenance Near Waterbodies
10.5 Maintenance of Structures for Wildlife
10.6 Maintenance of Stormwater Facilities
10.7 Maintenance of Roadside Public Facilities
10.8 Management of Portable Sanitary/Septic Waste Systems
10.9 Maintenance of Shoulders and Roadway Appurtenances
10.10 Sweeping and Vacuuming of Roads, Decks, Water Quality Facilities, and Bridge Scuppers
10.11 Maintenance Stewardship Practices for Slopes, Drainage Ditches, Swales, and Diversions
10.12 Erosion and Sediment Control in Maintenance
10.13 Recycling in Roadside Maintenance Operations
10.14 Preserving Air Quality in Maintenance and Operations
10.15 Painting Operation Stormwater BMPs
10.16 Road Waste Management
10.17 Stockpiling, Spoil Disposal or Placement of Inert Fill
10.18 Maintenance of Soils
10.19 Emergency Actions
10.20 Field Review of Roadside Maintenance Operations
Lists: Examples | Tables | Figures
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