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OC Road Going Green Externally
Alternative Street Widths
Reduce street widths to reduce unnecessary impervious areas, where traffic conditions or mobility is not impacted, including:
Alternative street parking configurations, vehicle pullout space, connected street networks, prohibiting parking near intersections, and narrower roadways should be considered where roadway conveyance and operations characteristics will not be compromised by such modifications to standards and the County’s Master Plan of Arterial Highways.
Other roadway typical section changes may include accommodating landscaped parkways through narrower sidewalks, where practicable and appropriate for safe pedestrian movement. Narrower sidewalks, when separated from the travelway by a parkway, use less concrete to construct (saving scarce construction funds and promote reduce carbon emissions in manufacturing the concrete), allow for road greening through landscaping, and provide a buffer between the sidewalk and the roadway.
Vegetated Swales 4
Vegetated swales are open, shallow channels (drainage ditches) with vegetation covering the side slopes and bottom, that collect and slowly convey runoff flow to downstream discharge points. They are designed to treat runoff through filtering by the vegetation in the channel, filtering through a subsoil matrix, and/or infiltration into the underlying soils. Vegetated swales trap particulate pollutants (suspended solids and trace metals), promote infiltration, and reduce the flow velocity of storm water runoff. Vegetated swales can serve as part of a storm water drainage system and can replace curbs, gutters, and storm sewer systems in appropriately situated locations.2
Pros: Reduction of peak storm flows, removal of pollutants, promotion of runoff infiltration, lower capital costs, and an aesthetic improvement (value) if properly designed, vegetated and maintained.
Cons: can be difficult to avoid channelization, may not be appropriate for industrial sites or locations where spills may occur, cannot treat a very large drainage area (runoff may be divided and treated using multiple swales), a thick vegetative cover is needed for these practices to function properly, impractical in areas with steep topography, (not effective and may erode if too steep), may not flourish in dryer climates/locations, may have regulatory permitting implications depending upon vegetation type, and may have an on going maintenance cost 2.
Implementation: use swales wherever the site provides adequate space (adequate right-of-way) and in place of curbs and gutters along parking lots (generally in rural, not urban areas). Vegetated swales should not be constructed in gravelly and coarse sandy soils which may not easily support dense vegetation.3
Use the following:
- Soils: Alkaline soils and subsoils should be used to promote the removal and retention of metals. 3
- Vegetation: A fine, close growing, water-resistant grass should be used (i.e. reed canary grass, grass-legume mixtures, and red fescue, pending permitting considerations) because increasing the surface area of vegetation exposed to runoff improves the natural filtering effectiveness of the swale system. 3
- For suggested channel configuration, sizing procedures, flow, and construction information please refer to: www.ircgov.com
Street bioretention 4
Installing tree boxes to remove runoff (normal storm flows and urban irrigation “over watering”) from the street with bioretention features are a versatile green street strategy. Many natural processes occur within bioretention cells: infiltration and storage reduces runoff volumes and attenuates peak flows; biological and chemical reactions occur in the mulch, soil matrix, and root zone (breaking down pollutants); and storm water is filtered through vegetation and soil.
An allowable diversity of shapes, sizes, and layouts bioretention can support implementation. Street configuration, topography, soil conditions, allowable right of way and space available influence the design of bioretention features. Clearance to above and below ground utilities may be an obstacle, however. Clearances that apply to storm drainage pipe and structure placement also apply to bioretention facilities. 2
Landscaping
When implementing any plant based biological greening features, choose plants that flourish in regional climate conditions, are adapted to periodic flooding, are low maintenance, and depending upon soil type, are salt tolerant. Landscaping also has the dual feature of providing a calming effect and an aesthetic appeal, to any roadway project.
One common method of landscaping is inclusion of street trees along the roadway parkway. Street trees provide ecological benefits via conversion of carbon dioxide to oxygen through photosynthesis, provide a complementary visual improvement to the streetscape environment, and can improve surrounding area property values. Trees need to be planted with adequate and appropriate soil volume, a good soil mixture and enough space to grow to their full size.4
Permeable Pavement 4
Permeable pavement is defined as pavement that allows infiltration of waters through its structural composition. Such pavements provide structural support and conveyance (to vehicles, pedestrians, bicyclists, etc.), runoff storage, and pollutant removal through filtering and absorption.
Infiltration of storm flows is quickly becoming one of the center pieces of water treatment across the United States. This simple yet effective process collects runoff from impervious surfaces (buildings, walkways, parking lots, etc.) and directs it to underground retention systems, to treat the water by soil filtering and recharge streams, lakes, rivers and underground aquifers, mimicking the natural water cycle. One of countless such industry articles that addresses this methodology can be found in the November 2009 edition of CE News, entitled, “Economic Optimization of Sustainable Subsurface Infiltration Systems”. www.cenews.com
Types: Permeable concrete, permeable asphalt, permeable interlocking concrete pavers and grid pavers.
Comparison: Similar in form to impervious pavements, but are open graded or have reduced fines and typically have a special binder added, to allow infiltration of waters.
Pros: May minimize vehicle hydroplaning due to roughened surface and reduced ponding of flows, reduction of storm waters leaving a site or area, increased infiltration and potential to recharge of below ground aquifers, and possible reduced road noise.
Cons: Initial costs may be higher than equivalent non-permeable pavement, maintenance, durability, and placement for use in areas that have an existing permeable or manufactured substrate.
Implementation: Replace impervious surfaces in non-critical areas such as sidewalk and driveway approaches, alleys and municipal parking lots. This medium is not currently recommended for general or wide spread use in through travel lanes for motor vehicles.
Fuel-Efficient and Alternative-Fuel Vehicles
Providing sufficient fuel to vehicle fleets can put a significant dent on municipal budgets. Minimizing petroleum usage decreases dependence on foreign oil, reduces GHG emission from burning fossil fuels, improves air quality and helps free scare transportation dollars for other related uses. 5
Implementation: Consider upgrading to alternative-fuel vehicles and low-emission (electric or hybrid) vehicles for staff to use when traveling to offsite meetings. Such vehicle replacements should be timed when vehicles reach their normal depreciated lifespan, or when repairs approach the remaining depreciated value of the vehicle.
Funding: Grant funding is available to help reduce the cost when converting to fuel-efficient/alternative-full efficient vehicles, through the Congestion Mitigation and Air Quality (CMAQ) Improvement Program. 5 Inquiries may be sent to  AB118@energy.state.ca.us
Valve Caps
Valve caps are devices that indicate tire pressure; some have a light emitting diode (LED) lights that flash when tire pressure falls below standard by 4 PSI or more. 6 Keeping tires properly inflated can provide fuel savings of up to 140 gallons per vehicle per year, prolonging tire life by 10-20%, make vehicles safer and keep up to 2880 lbs. of carbon dioxide (C02) per vehicle out of the atmosphere. Valve caps should be installed on vehicles as funds become available.
Pavement recycling
Reduce waste by re-using existing Asphalt Concrete (AC) as either driving surface or subgrade for new driving surface. Also consider, where appropriate, in-place recycling of AC, which reduces truck trips needed to export old (removed) AC and import new AC; saves gas, reduces air pollution
Miscellaneous Road Greening Activities
Preserving Pavement Responsibly
Preserving pavement by crack sealing saves money, time and protects our road infrastructure investment. Addressing pavement cracks before they widen and allow water intrusion into the roadway subbase, protects the integrity and structural composition of the roadway. Crack sealing uses less energy than any other recognized pavement preservation methodology, leaving a small carbon footprint and adding years of service to most pavements. Through its Pavement Management Program (PMP), the County OC Public Works-Operations uses crack sealing as one component of its PMP, to help effectively maintain the County’s 320 miles of unincorporated roadways, practicing good stewardship of the public funds, while keeping our carbon footprint to a minimum.
Protected Permissive Left Turn (PPLT)
The use of protected/permissive left-turn (PPLT) traffic signal operation has, over recent years, proliferated throughout California and the United States. The PPLT traffic signal operation provides a dual function where an exclusive left-turn movement, under the arrow display, is followed by a permissive left-turn movement on a green ball (under the leading protected left turn scenario). The green ball indication allows drivers to continue making left turns, as a permissive movement, depending on suitable gaps in approaching traffic. The benefit of this PPLT type of signal operation is a reduction in stops and delays, which reduces driver frustration, fuel consumption, and pollution.
Pros:
- Reduces delays and stopped time on coordinated systems.
- Allows for selective use of shorter cycle lengths at each intersection.
- Reduces fuel consumption.
- Reduces pollution.
- Provides high signal system efficiency (slightly less than only permissive in the worst case and as good in the best case) because it allows for all left-turn phasing combinations (with special equipment), thus producing the best fit into the green band, while still providing protected left turns. This benefit is high both during peak travel periods, when protected left-turn phasing has the greatest effect; and off-peak, when the larger number of acceptable gaps in through traffic fllow left turners to proceed without waiting for the green arrow.
- Fewer right-angle accidents may occur than under permissive-only operation, due to the presence of the protected left-turn phase.
Cons:
- Lost time due to various measures required to prevent left-turn trap phasing situations.
- Occasional driver confusion and resistance to acceptance
- Signal head configuration and placement not uniform throughout the area.
- Arterial system timing is difficult to use with protected/permissive operation.
The County of Orange has implemented PPLT at selected intersection in the North Tustin area, and continues to evaluate its use for new signals, and for signals whose controller or operating hardware has reached its maximum service life.
Black and Green: Sustainable Asphalt, Now and Tomorrow
The information presented below was obtained from the National Asphalt Pavement Association (NAPA) November/December 2009 article of the same name, Page 17, of their publication Hot Mix Asphalt Technology.
Long before “sustainability” became an eagerly pursued part of the American business plan, the asphalt industry initiated research and field practices that have constantly enhanced the viability of asphalt as an environmentally sound building material. The asphalt industry’s new sustainability report, titled, “Black and Green: Sustainable Asphalt, Now and Tomorrow,” is now available on NAPA’s website. The sustainability report explores in depth four green aspects of this building material.
- Reuse and recycling is the singular accomplishment of the industry’s sustainability initiative. Asphalt is the most recycled material in America. About 100 million tons of old pavement are reclaimed every year, with about 60 million tons reused in new asphalt mixes, and some 40 million tons used in other pavement-related applications, such as aggregate road base.
- Warm-mix technologies allow for production and placement of asphalt pavement material at lower temperatures than traditional methods. The potential for warm mix to reduce fuel consumption, cut greenhouse gas emissions, and enhance performance has won broad support among road managers and contractors. In five years following the first public demonstration of warm mix in the U.S. in 2004, scores of warm mix projects have been constructed in 40 states.
- Perpetual Pavement is the name given to an asphalt pavement that is designed not to fail. Construction is in layers whose properties serve a combination of different functions; they all add up to an extraordinarily long-lasting pavement. Routine maintenance involves infrequent milling of the top layer for recycling, then placing a smooth, quiet, durable, safe new overlay. Even decades after construction, a Perpetual Pavement will not need to be completely removed and replaced. In the world of pavement, this is the ultimate in economic and environmental sustainability.
- Porous and open-graded asphalt pavements have been shown to have a dramatic beneficial effect on water quality. These pavements have been used widely for over 30 years with an excellent record of success.
- In “Smoothness Matters: The Influence of Pavement on Fuel Consumption,” Page 18, Dr. Howard Marks critiques and synthesizes research indicating how smooth asphalt pavements can reduce fuel consumption of a broad scale.
- As emphasis on green practices increases, acceptance of porous pavements is growing and contractors are among those leading the way. In “Contractors Embrace Porous Pavements,” on Page 31, some examples of contractor leadership in the use of porous pavements, is profiled.
- The conventional wisdom on pavements’ role in creating the urban heat island effect is challenged in the thought-provoking piece “Urban Heat Islands: Not a Black and White Issue,” Page 40.
- For contractors seeking credits under the LEED green building rating system, “Obtaining LEED Credit for Reflective Asphalt Pavements” provides a summary of the latest research from the Nation Center for Asphalt Technology (Page 42).
According to NAPA, of the 2.6 million miles of paved roads in the United States, over 94 percent are surfaced with asphalt. Approximately 85 percent of the nation’s airfield pavements and 85 percent of the parking lots are also surfaced with asphalt. There are about 4,000 asphalt mixing plants located in the United States and the industry employs, directly or indirectly, 300,000 U.S. workers. Because of the vast use of this material, even small changes in asphalt pavement technology can make a big difference.
Visit www.hotmix.org to access the asphalt industry’s sustainability report.
Civil Engineering Design for Green Building
Another aspect of Road Greening is how adjacent land development is designed so that its environmental impact is as small as possible. Design of land development must consider building type, size, materials and siting. On the building site, whether the building will be designed using U.S. Green Building and Council Leadership in Energy and Environmental Design (LEED) guidelines, whether certification will be sought, the storm water system design, including detention and retention facilities, porous pavement bio swales, stormwater reuse, etc. Many industry articles are available; however, a simple overview may be obtained by reading the referenced article on this topic, on Page 30 in CE News, September 2009 edition www.cenews.com.
Use of Reclaimed Asphalt Pavement
The use of Reclaimed Asphalt Pavement (RAP) in new asphalt pavement has many advantages to the environment, including a reduction in the carbon footprint, conservation of landfill space, and a reduction in material costs. The National Asphalt Pavement Association (NAPA) discusses such in an article in their September/October 2009 Hot Mix Asphalt Technology publication: www.hotmix.org.
Cement Production Energy Reductions
The cement industry is researching ways to reduce its carbon footprint. Cement is a component of Portland cement concrete, used in the construction of roads, building, bridges, retaining walls, drainage facilities, etc. The manufacture of cement generates Carbon dioxide (C02), which is derived from limestone as it is calcined (heated to fusion) with other ingredients in a rotary kiln. At calcining temperatures of 2,800 degrees Fahrenheit and higher, cement manufacture consumes significant amounts of coal or other fossil fuels, which in turn emit C02 during combustion to heat the raw materials for cement. While much of the heat is captured in the kiln exhaust, some waste heat is ultimately vented to the atmosphere. The Portland Cement Association (PCA) acknowledges this energy use and C02 emission concern, and is developing policies and improving the manufacturing process, including plans to reduce C02 emissions 10% per ton of product below the 1990 base line. For more information, please visit the PCA at: www.cement.org.
Green Green Green – LEED the construction industry
Miscellaneous Websites and Documents
- The website, “Real Transportation Solutions for Greenhouse Gas Emissions,” includes best practices, state examples, research findings and links to other sites. The site is structured with the assumption that man-made climate changes is taking place, and that steps by public agencies can reduce future global warming: www.transportation1.org
- The United State’s Environmental Protection Agency’s (EPA) main website contains information on managing wet weather with green infrastructure, at the following weblink: http://cfpub.epa.gov
- A link to the EPA’s “Municipal Handbook – Green Streets,” which is now a 4th term MS4 permit requirement for local municipalities to incorporate into road/ street/ highway projects: http://www.epa.gov
- Another outstanding resource is the manual on green infrastructure prepared by the City of Los Angeles. The entire manual is available at: http://lastormwater.org
- The County of Orange OC Watersheds also has a wealth of information on proper collection and treatment of waters.
Their website can be reached at: www.ocwatersheds.com
- Green Government, Driving on Sunshine
References:
- Storm water Best Management Practices in an Ultra-Urban Setting: Selection and Monitoring by U.S. Department of Transportation Federal Highway Administration. Available at: http://www.fhwa.dot.gov
- California Storm water Best Management Practice Handbook - New development and Redevelopment. Available at: www.cabmphandbooks.com
- Municipal Technology Branch
- Managing Wet Weather with Green Infrastructure Municipal Handbook, by Robb Lukes, Christopher Kloss, and Low Impact Development Center
- Moving Toward Fuel-Efficient and Alternative-Fuel Fleets: 10 Questions Local Officials Should Ask, by Kathleen Les
- Finding balance in everything, Diary of a public works director, Michael Mucha, Director of Public Works, City of Olympia.
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