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Chapter 3
Designing for Environmental Stewardship in Construction & Maintenance
3.1. Beyond Mitigation: Projects to Achieve Environmental Goals


State transportation agencies have been devoting increasing attention to the relation of design considerations to DOTs' ability to effectively steward the environment in construction and maintenance. Raising the bar on environmental performance in construction and maintenance requires cooperation with design and attention to a host of factors at an early stage in the process (planning or design) when appropriate design changes can be made and increased funding may be sought. State DOTs increasing emphasis on and guidance for designers is evident in the proliferation of design manuals that are available. AASHTO maintains a list of links to state DOT manuals on their website, at Almost every DOT has a manual for drainage and water quality considerations in design. The most widely available guidance is not duplicated here. Rather, this section focuses on more recent and emerging stewardship practices in design that assist construction and maintenance staff in delivering positive environmental outcomes.

As part of their stewardship commitments, environmental planning, or process improvement efforts, some state DOTs have begun to systematically encourage and include non-compliance- related enhancements in project design and construction.


3.1.1 Environmental Betterments and Dual Purpose Projects
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Dual Purpose Projects at Caltrans

Caltrans has explored "dual purpose" projects to achieve both environmental and transportation objectives. To further explore opportunities for enhancement as well as avoidance and minimization of environmental impacts, Caltrans is working with The Nature Conservancy of California to overlay the road network with priority habitat conservation areas statewide. A previous effort co-sponsored by Caltrans examined statewide wildlife habitat connectivity needs and associated opportunity areas for conservation. Caltrans has pursued other types of "dual purpose" community and environmental benefit projects where opportunities arose.

NYSDOT's Guidelines and Procedures for Environmental Betterments

NYSDOT's environmental initiative guidelines and procedures encourage DOT Regional Design Groups to look for opportunities for joint development with municipalities, other agencies, and private developers whereby design, construction, land acquisition and maintenance responsibilities can be mutually and equitably shared, while accomplishing community goals. The guidelines allow specific environmental elements or facilities requested and funded by others (e.g., municipalities, other agencies, and environmental groups) to be incorporated in DOT capital and maintenance projects as "Environmental Betterments," wherever practicable. Such elements or facilities include landscaping, park amenities, historic building preservation, noise barriers, created wetlands, stream restorations, stormwater basins, habitat improvements, and new municipal sanitary sewer lines, storm sewer lines and water mains that provide an environmental benefit. Such " environmental betterments" are intended to benefit from the "economies of scale" possible on large public works projects and the particular equipment and skilled personnel available in such cases, that could cost sponsors and stakeholders less than individual projects designed, constructed, and let by themselves. NYSDOT's Stewardship Initiative calls for the following practices or features to be incorporated into DOT capital and maintenance projects, as appropriate: [N]

  • Practice of context sensitive design.
  • Street ambience enhancements (e.g., benches, decorative paving, bollards, period lighting fixtures).
  • Restoration of historic highway related features (e.g., historic lighting fixtures, stone walls, guiderails).
  • Measures to retain the integrity of historic parkways and bridges.
  • Increased wild flower plantings.
  • Additional landscaping to enhance the appearance of noise barriers.
  • Increased landscape plantings to improve roadside appearance and streetscapes.
  • New or rehabilitated fishing access and trail head parking areas.
  • New or rehabilitated boat and canoe launch sites.
  • New or rehabilitated historic markers and interpretive signing.
  • Increased signing of important waterways and watersheds.
  • New or rehabilitated scenic overlooks.
  • Retrofits of existing highway drainage systems with created wetlands and stormwater management facilities.
  • Soil bio-engineered stream banks.
  • Plantings, boulders, deflectors and other techniques to improve fisheries habitat.
  • Culverts for wildlife crossings.
  • New or rehabilitated wildlife viewing sites.
  • Wildlife habitat improvements.
  • Mitigation and enhancement for past wetland impacts.
  • Restored and enhanced wetlands.
  • Acquisition of endangered species habitat.
  • Acquisition for preservation of regionally important wetlands and upland habitat.
  • Acquisition of scenic easements.
  • Improvements to highway entrances of public parks, wildlife management areas, and historic sites.
  • Replacement of fixed-time traffic signals with vehicle activated signals.

As part of NYSDOT's proactive outreach effort, Regional Design offices have invited local municipalities, environmental groups and agencies to combine their funded and designed environmental elements or facilities with ongoing DOT projects. In some cases, NYSDOT has provided added design services to assure that the community's "environmental betterment" work is appropriately integrated into the transportation project plans and specifications. NYSDOT can also provide contract letting and construction inspection of the Environmental Betterment work at no charge to the municipality, other agency or environmental group.

Since NYSDOT's Environmental Initiative is a component of the Department's Capital Program Update process, Regional Planning and Program Managers are required to include Environmental Initiative projects on their updated program. Regions identify those projects that have environmental or context sensitive design work which goes above and beyond regular mitigation or permit requirements and track those elements as a project attribute in the Department's Project and Program Management Information System (P/PMIS). Various work types allow environmental initiative projects to be grouped by a specific activity, as outlined in NYSDOT's Environmental Initiative Statement and description of the Dedicated Environmental Benefit Projects. This overview also outlines NYSDOT's further rationale for investment in such public goods: [N]

Example 3 : NYSDOT Initiative - Environmental Benefit Projects

NYSDOT will fund and implement a number of environmental benefit projects that are well-suited to the Department's mission and capabilities. To program environmental enhancements on property owned by the New York State Department of Transportation will be a simple, straightforward and visible demonstration of environmental commitment. These projects will be designed to:

Improve water quality because studies done by the New York State Department of Environmental Conservation (DEC) have shown that non-point source runoff is now the major cause of water pollution. Non-point source pollution enters a water body from diffuse origins on the watershed and does not result from discernible, confined or discrete convergences such as a pipe or ditch. NYSDOT, with its extensive network of state highways, is in an excellent position to assist in improving New York's water quality. Since, non-point source water pollution control is most practically achieved through the construction of stormwater control measures that NYSDOT routinely incorporates into its projects. NYSDOT will also retrofit existing highway drainage systems by designing and building:

  • Created wetland and stormwater management structures
  • Bioengineered streambanks.
  • Specialized water quality inlet structures

Restore wetlands because the initial construction of New York State's transportation infrastructure caused negative impacts on wetland acreage, function and value. During the last two decades, the New York State Department of Transportation has gained extensive experience both in delineating state and federal wetlands and in avoiding, minimizing and mitigating adverse impacts to wetlands. NYSDOT will continue to use this new knowledge to go beyond regulatory state and federal no-net-loss goals by helping to increase New York State's wetland acreage and function by:

  • Improving or restoring wetlands affected by federal-aid highway projects that were done before regulatory mitigation was required.
  • Constructing additional wetland acreage in projects beyond that required for state and federal wetland permits.
  • Working cooperatively with The Nature Conservancy and the resource agencies to preserve important existing wetland sites.
  • Creating new wetlands to control non-point source pollution as well as to provide other wetland functions, such as wildlife habitat.

Protect fish and wildlife because fisheries habitat in New York State has been degraded by the channelization and siltation of state waterways, and DOT has the capability to deliver restoration measures in an efficient and practical manner. The New York State Department of Transportation will protect wildlife by planting specialized food and cover crops along state highway rights-of-way and by providing more and safer wildlife crossings under state and local highways. For example, NYSDOT will design and install:

  • Boulders and stone weirs to improve fisheries habitat
  • Culverts for wildlife crossings
  • Plantings for wildlife habitat

Promote eco-tourism because people travel on state highways. And, through access to nature, people develop a deeper sense of why the environment warrants protection. Eco-tourism is a growing and sustainable part of New York State's economy. Because a large part of the eco-tourism experience depends on the appearance of state roadsides as well as access to natural features, the New York State Department of Transportation will develop:

  • New or rehabilitated fishing access and trailhead parking areas
  • Historic markers and other interpretive signing
  • Improved bikeway and pedestrian facilities
  • New scenic overlooks

Enhance transportation corridors because as a state agency, the New York State Department of Transportation's customers include the traveling public and the people who live and work in New York State's transportation corridors. They deserve improvements in the quality of their lives that can be achieved through:

  • Providing streetscape amenities
  • Wild flower plantings
  • Landscaping to enhance the appearance of noise barriers
  • Reestablishing street trees in historic districts
  • Rehabilitating comfort stations and rest areas

The New York State Department of Transportation will continue to make every effort to:

Reduce environmental toxins by:

  • Using salt and sand for highway anti-icing and de-icing as judiciously as possible
  • Sweeping roadsides better and more often
  • Reducing herbicide applications
  • Cleaning up wastes previously generated on NYSDOT projects and at NYSDOT facilities

Improve air quality because up to half of the air pollutants emitted in New York State are emitted by single occupancy vehicles; that is, by cars with only a driver. To reduce these emissions, the New York State Department of Transportation will:

  • Implement Transportation Demand Management practices
  • Encourage alternatives to single-occupancy vehicle commuting
  • Expand Ozone Alert Day initiatives
  • Promote the use of alternative fueled vehicles
  • Provide facilities for pedestrians and bicyclists
  • Support mass transit

Increase the use of recycled materials because New York State's environmental policy calls for recycling as the first choice in dealing with solid waste. As a leader in this policy initiative, the New York State Department of Transportation will pilot and promote the use of recycled:

  • Tires in highway embankments
  • Glass, plastics, and aggregate in pavement mixes
  • Plastic, rubber, and aggregate in noise walls

Preserve and enhance our New York State heritage because our historic and our natural heritage belongs to all New Yorkers. Because of the nature of its work, NYSDOT is in a unique position to enhance this heritage by:

  • Preserving historic structures
  • Promoting state bicycle routes and greenways
  • Increasing highway tree plantings and other landscaping
  • Providing streetscape amenities
  • Increasing roadside plantings and maintenance for aesthetic improvement

Through active integration of environmental concerns into the Department's daily operations and coordination with regulatory agencies, environmental groups, municipalities and concerned citizens, the Initiative will attain the goals set forth above.

Florida DOT Policy to Consider Wildlife Crossings and Bridge Extensions

The Florida Department of Transportation (FDOT) began to consider wildlife crossings and bridge extensions on projects in the 1970s and 1980s to reduce roadkills and to restore ecological processes such as water flow across the landscape. In the late 1980s, FDOT installed underpasses on I-75 through the Everglades/Big Cypress National Preserve area, resulting in the virtual elimination of vehicle collisions with the endangered Florida panther.

Because significant efficiencies and ecological gains can be made by coordinating wildlife crossing installation with statewide efforts to map conservation areas and large scale linkage needs, FDOT and the Florida Game and Fresh Water Fish Department developed a decision-based geographic information system (GIS) computer model for FDOT road improvement projects associated with road mortality of wildlife and other environmental impacts. This system is integrated with other state environmental initiatives such as the greenways and CARL (Conservation and Recreation Lands) programs. The computer model program will enable FDOT to appropriately schedule future projects according to critical environmental and transportation improvement needs. An interactive CD-ROM allows the user to perform multiple scenarios and develop their own priorities, and contains all necessary data and information to perform analyses.

Boston's Central Artery/Tunnel Project Design to Enhance Walkability

Boston's "Big Dig," as the Central Artery/Tunnel Project is commonly known, has been acknowledged for its contribution to Livable/Sustainable Communities. The project replaces an elevated highway with an underground facility, and in the process, enhances the compact, walkable character of downtown Boston. The project is adding a series of parks and greenways in the path of the old elevated expressway that cut off downtown Boston from its waterfront, as well as in other locations scattered throughout the city. A reduced number of on- and off-ramps help separate local traffic from interstate traffic.


3.1.2 Maintaining or Improving the Natural Environment as Transportation is Built
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An increasing number of DOTs are incorporating ecosystem conservation into their planning processes; the General Accounting Office noted that DOTs in Oregon, South Dakota, Colorado, and North Carolina "reported extensively considering ecosystem conservation in transportation planning using several approaches. The Oregon Department of Transportation has included a policy in its long-range plan to, among other things, maintain or improve the natural and built environment, including fish passage and habitat, wildlife habitat and migration routes, vegetation, and wetlands. The long-range transportation plans of Colorado and North Carolina each contain specific references to goals or policies to conserve ecosystems, while South Dakota's plan contains a more common, less specific goal aimed at protecting the environment." [N]


3.1.3 Cultural Resource Enhancement Efforts
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Efforts to preserve and enhance public enjoyment of cultural resources are included among Context Sensitive Design/Solutions initiatives at state DOTs. Such efforts often include such environmental stewardship practices and improvements as:

  • Extending trails or sidewalks to allow public access to historic sites and areas
  • Visual screening of sensitive sites and structures
  • Scenic easements to protect cultural resources from inappropriate development
  • Special signage design/placement
  • Preservation of historic landscape elements and visual contexts
  • Preservation of the historic contexts of cultural resources through historical studies and publication of public interpretive materials

AASHTO's Environmental Stewardship Demonstration Program profiles these and other project and programmatic cultural resource stewardship projects, about which further information is available on-line: [N]

AASHTO's Center for Environmental Excellence maintains background information about information about Section 106 of the National Historic Preservation Act and Section 4(f) of the Department of Transportation Act on-line along with Recent Developments, Documents and Reports, Success Stories, and Related Links. A notable practice and use as a design resource in the state of Minnesota is MN/Model - A Predictive Model of Precontact Archaeological Site Location for Minnesota .

Often cultural resources enhancements are included in general project costs. Other times, such enhancements are funded as separate Transportation Enhancements (TE) activities, which are federally funded, community-based projects that expand travel choices and enhance the transportation experience by improving the cultural, historic, aesthetic and environmental aspects of transportation infrastructure. Transportation Enhancement funds are apportioned to the state DOTs through a minimum 10 percent set aside of each state's STP funds. TE projects must be one of 12 eligible activities and must relate to surface transportation. For example, projects can include creation of bicycle and pedestrian facilities, streetscape improvements, refurbishment of historic transportation facilities, and other investments that enhance communities and access. The National Transportation Enhancements Clearinghouse contains descriptions and photos for a full range of such efforts, as well as links to learn the basics of the TE program, view a Guide to Transportation Enhancements, access state-specific information, order free documents, or assistance. Federal legislation related to TE is accessible through the Federal Highway Administration (FHWA) TE Web site. In addition to a project list, NTEC maintains a state program policy and procedures database that is updated periodically as changes occur. [N] Some state DOTs are more active in implementing the TE program and using TE dollars than other states. Several states, including Wisconsin, Massachusetts, and Alaska, have funded numerous TE-eligible projects using funding sources other than the TE set aside. [N] The following trail extension project profiled by NTEC is a prime example of a cultural resource enhancement project, in the sidewalk/trail extension category, undertaken with DOT support:

New Hampshire Lincoln-White Mountain Trail

Figure 2 : Lincoln, NH White Mountain Trail

The multi-use trail passes beautiful fall foliage

New Hampshire DOT facilitated construction of over 2.5 miles of sidewalk and multi-use path through what was once an ailing mill town in New Hampshire's majestic White Mountains. The town of Lincoln now bustles year round with tourists bound for hiking, biking or skiing, after town officials recognized its strategic importance as a gateway to the White Mountains, and focused efforts on better connecting the community with recreational opportunities in the area. The path was built over the former site of a penstock, a sluice used to transport water to the mill, between the Pemigewasset River and Route 112. Residents of the town can now safely travel adjacent to Route 112 by foot, and bicyclists coming down from the Noon Mountain ski area or through Franconia Notch can use the path to enter town. Parts of the path abut the White Mountain National Forest, where pedestrians and bicyclists can take in the beauty of the mountain scenery and, in the autumn, enjoy the region's spectacularly colored foliage. [N]

Figure 3 : NH White Mountain Trail Bridge

The multi-use trail crosses a stream


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Continue to Section 3.2 »
Table of Contents
Chapter 3
Designing for Environmental Stewardship in Construction & Maintenance
3.1 Beyond Mitigation: Projects to Achieve Environmental Goals
3.2 Context Sensitive Design/Solutions
3.3 Avoiding Impacts to Historic Sites
3.4 Designing to Accommodate Wildlife, Habitat Connectivity, and Safe Crossings
3.5 Culverts and Fish Passage
3.6 Stream Restoration and Bioengineering
3.7 Design Guidance for Stormwater and Erosion & Sedimentation Control
3.8 Drainage Ditches, Berms, Dikes, and Swales
3.9 Design for Sustainable, Low Maintenance Roadsides
3.10 Designing to Reduce Snow, Ice, and Chemical Accumulation
3.11 Designing to Minimize Air Quality Problems
3.12 Design and Specification for Recycling
3.13 Designing to Minimize Noise
3.14 Lighting Control/Minimization
3.15 Design for Sustainability and Energy Conservation
3.16 Safety Rest Areas, Traveler Services, and Parking Area Design
Lists: Examples | Tables | Figures
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