Sustainable Highway Construction Guidebook (2019)

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9 This chapter defines sustainability, describes its characteristics, and discusses major trends in highway construction sustainability thought and practice. It gives the practical background necessary to understand, communicate, implement, and evaluate sustainable highway construc- tion practices. 2.1 Sustainability Defined This guidebook defines sustainable highway construction practices as construction practices able to assist in (1) building highways, (2) preserving and restoring surrounding ecosystems, (3) meeting basic human needs such as equity, employment, health, safety, and happiness, and (4) managing resources wisely (including, but not limited to, money). This definition is con- sistent with approaches described in other transportation sustainability efforts such as NCHRP Report 708: A Guidebook for Sustainability Performance Measurement for Transportation Agencies (Zietsman et al., 2011); NCHRP Report 750, Volume 4: Sustainability as an Organizing Principle for Transportation Agencies (Booz Allen Hamilton, 2014); and FHWA’s INVEST self-evaluation tool and sustainable pavements program. 2.1.1 Practical Definition for this Guidebook While reasonably comprehensive, the previous definition is difficult to use in determining if and how a highway construction practice might qualify as sustainable. Therefore, this guidebook uses a practical definition of sustainability that adds an above-and-beyond requirement: Sustainable construction practices (SCPs) are those that (1) go above-and-beyond standard practice and/or required national regulatory minimums, or (2) show innovation in meeting these standards and minimums in support of people and the environment. By defining sustainability as something that goes “above-and-beyond” for people and the environment, this guidebook equates sustainability efforts with doing more than is already required by standard or regulation. Sustainability is often presented this way in construc- tion. Regulatory compliance and standard practice are an important component of the more comprehensive sustainability definition (Section 2.1), but they are typically addressed as their own topics in procurement and specifications. Sustainability, however, is a topic that typically addresses above-and-beyond practices not covered elsewhere. The intent of this guidebook’s practical sustainability definition is to encourage highway construction practices beyond compliance or standard practice, and provide ideas that may spark creativity and ingenuity within the highway construction industry. Because this guide- book’s scope is limited to current technology, the sustainable highway construction practices and ideas presented here are, in the right context, ready for implementation. C H A P T E R 2 Background

10 Sustainable Highway Construction Guidebook 2.1.2 Sustainability in a Broader Sense Sustainability, the idea that humans can and should live in harmony with nature, is a common theme throughout recorded history. While most civilizations, ancient and mod- ern, have recorded eloquent expressions of this idea, achieving it in modern times has been problematic. As a result, sustainability is often expressed as a goal or aspiration. In modern times, probably the most famous expression of sustainability comes from the Brundtland Report (1987) of the United Nations World Commission on Environment and Development: “Sustainable development is development that meets the needs of the present without compromising the ability of future generations to meet their own needs.” While many modern sustainability definitions are based on this quote, it is a difficult one to operationalize. In other words, what exactly is “. . . development that meets the needs of the present without compromising the ability of future generations to meet their own needs?” In 1989, Dr. Karl-Henrik Robért founded The Natural Step and provided a system definition to sustainability (https://thenaturalstep.org/approach/): “In a sustainable society, nature is not subject to systematically increasing 1. . . . concentrations of substances from the earth’s crust (like fossil carbon dioxide and heavy metals). 2. . . . concentrations of substances produced by society (like antibiotics and endocrine disruptors). 3. . . . degradation by physical means (such as deforestation and draining of groundwater tables). 4. And in that society there are no structural obstacles to people’s health, influence, competence, impartiality, and meaning.” These are specific, but lofty goals. They are likely only achieved over generations, and progress toward them is incremental. 2.1.3 Contribution and Impact of Highway Construction Sustainable highway construction is one small contribution to a sustainable society. In general, all societal and environmental systems interact with other systems. For example, highway construction interacts with fresh water, the local ecosystem, neighboring busi- nesses, highway users, natural resources, the local economy, and more. In a sustainable society, systems interact harmoniously with one another: they are interdependent and work to each other’s benefit. For instance, sustainable highway construction should contribute to and support a better transportation system, a better environment, and a healthy society and planet. The contribution of highway construction to national economic and greenhouse gas metrics is relatively small. For instance, highway and street construction put in place (as defined by the U.S. Census Bureau) in 2017 was $85 billion. This investment was about 0.3% of U.S. GDP (2017 U.S. construction was about 4.2% of U.S. GDP and highways and streets constituted about 7% of that construction total). In terms of greenhouse gas emissions, a rough estimate is 65,600 MTCO2e (metric tons of CO2 equivalent) global warming potential (GWP), which constitutes about 0.001% of the total U.S. greenhouse gas emissions (6,511 MTCO2e in 2016). Despite these small fractional contributions to the overall total, annual impacts of $85 billion in construction put in place and 65,600 MTCO2e are, by themselves, substantial and worthy of attention. Other substantial highway construction impacts beyond economic and greenhouse gas emis- sions include:

Background 11 • Energy consumption. Highways take energy to construct, maintain, rehabilitate, and recycle. Since the consumption of energy also produces greenhouse gases, the emission of greenhouse gas is also affected by these features. • Habitat. Highway construction can affect adjacent habitat, impede wildlife movement, and change wildlife distribution in an area. • Water quality. Highway construction impacts water quality through temperature changes, erosion, sediment, and site pollutants. • Hydrologic cycle. Highway construction can affect stormwater runoff and the amount of water infiltrated back into the ground. • Air quality. Materials production, construction equipment, and fugitive dust can impact local air quality. • Mobility and access. Highway construction can cause traffic congestion and road closures affecting mobility and access for people and freight. • Community. Highway construction can have local community impacts related to employ- ment, mobility, access, inconvenience, business availability, and more. • Non-renewable resources. Highway construction uses a significant amount of non-renewable natural resources. 2.1.4 About Sustainability • Sustainability has social (or human), environmental, and economic dimensions. This is a convenient way to deconstruct sustainability: it emphasizes that sustainability must include human well-being within a healthy environment but that efforts toward sustainability are bound by available resources like money and time. • Prioritization of sustainability dimensions is often necessary. It can be difficult to address all three sustainability dimensions simultaneously. For instance, it has been found that environmental and human concerns are negatively correlated, implying that human and environmental well-being may be (in practice if not in theory) mutually exclusive in many cases (Kaivo-oja et al., 2014). Organizations and projects can prioritize sustainability components but must be wary about how they do so. Ideally, prioritization is based on organization/project goals and objectives and is carefully considered to avoid long-term bias on a larger scale. • Sustainability is context-sensitive. What can be considered a sustainable practice depends on context: one situation may call for a different set of solutions than then next. Therefore, it is not possible to define a list of universal sustainable best practices. A bet- ter method, one that accounts for context, is to organize an approach to sustainability around desired sustainability outcomes with each outcome achievable through many dif- ferent means. • Sustainability elevates the value of human and environmental health in the long term. Historically, these ideas have been given lower priorities when compared to first costs. How- ever, there is substantial value in (1) elevating environmental or social issues above what they used to be and (2) considering impacts, costs, and benefits over the long term. Thus, while sustainability might consist of three dimensions (human, environment, economy), the economic dimension, and especially the immediate economic impact, has always been emphasized. Renewed interest in sustainability can, therefore, be interpreted as placing more emphasis on human, environmental, and long-term considerations. • Sustainability implies improvement. A sustainable society is a lofty goal, but one worth aspiring to. Constant improvement of existing practices in order to make progress toward the goal should be the aim.

12 Sustainable Highway Construction Guidebook • Sustainability goes beyond the bare minimum. Regulations and standard practice are the bare minimum. If improvement is required, then sustainability means going beyond the bare minimum. Thus, this guidebook’s definition of sustainability is based on practices that go beyond standard practice and the regulatory minimum. • Sustainability constantly evolves. What was once exceptional or innovative ultimately becomes standard practice and regulation. As minimum standards are raised, sustainability actions must also be improved. The SCPs listed in this guidebook may eventually become regulations or standard practice; or they may become obsolete. Thus, this guidebook also provides a process by which any highway construction practice can be evaluated for sustain- ability impacts. 2.2 Highway Construction Sustainability Trends This section presents broad industry trends that were found during the research supporting this guidebook (Section 1.5). There is some risk in generalizing these research findings since the research focused on specific publications, people, and groups familiar with construction and sustainability; it is not a random sampling of the industry. Nevertheless, these trends can be used to better understand how sustainability is thought of in highway construction, which may influence the use of this guidebook and approaches to sustainability in the future. 2.2.1 Sustainability Values • Most organizations value sustainability. A survey question asked to what degree respon- dents agreed with the statement, “Sustainability is a core value of my organization/company.” Of the 190 responses received, 18.4% agreed strongly and another 50.5% agreed. • In highway construction, sustainability is not as important as cost or schedule. Chiefly identified in workshop discussions, this means that when project choices are made between sustainability, cost, and schedule commitments, sustainability is often the lowest priority. This could be the result of sustainability having less representation in procurement and contracts, and less accountability over the life of a project. • There is some consensus that sustainability involves three components: human, environ- ment, and economic. A survey question asking participants to define sustainability in their own words received 182 responses. Most responses mentioned or implied a combination of human/environmental/economic well-being, but some did not mention them specifically. Of the responses, 38 mentioned some form of human well-being, 85 environmental well- being, and 55 economic well-being. This was reinforced through interview responses and workshop comments. • Durability and long life of infrastructure is integral to sustainability. A survey question asking participants to define sustainability in their own words received 182 responses. Of the responses, 57 directly referred to durability and endurance concepts (“long life,” “lasts a long time,” etc.). Several specifically stated that durability/long life issues with minimal mainte- nance were more important than environmental stewardship. Only 5 responses defined sus- tainability as the sustainability of infrastructure assets specifically. • Sustainability efforts are driven largely by cost. A survey question asking participants to rank five motivations for sustainability received 186 responses. “Optimization of life-cycle cost of highway infrastructure” was ranked the highest and most often compared to effi- ciency, minimizing environmental impact, increasing recycled/renewable materials use, and waste reduction. Several interview responses stated that their organization’s sustainability was largely driven by cost or cost savings.

Background 13 • There is no leading entity in highway sustainability. None was identified in the literature review, survey, interviews, or workshop. Unlike the building industry, which has several lead- ing entities [e.g., the U.S. Green Building Council and its Leadership in Energy and Environ- mental Design (LEED) rating system or the Living Future Institute], there is no consensus leader in the highway industry that identifies SCPs and specifies what constitutes their accom- plishment. While there are several rating authorities (for instance, INVEST, Greenroads, Envision), many organizations rely on their own definitions of SCPs and internally-generated narratives to communicate their efforts. As a result, definitions differ from organization to organization, and quantification is rare beyond Global Reporting Initiative Standards, which are focused on the impact of a company’s operations (e.g., energy use for corporate opera- tions) and not on the infrastructure it creates (e.g., roads and bridges). 2.2.2 Use of Sustainable Construction Practices • There is little industry guidance on procuring sustainability in highway construction. This point was chiefly identified in workshop discussions. While sustainability continues to be included in procurement, there is no standard of practice and little formal guidance on how to do so. Little guidance was found in the literature review, and workshop participants identified lack of guidance as a significant roadblock. • Materials recycling/reuse is the most commonly identified SCP. Survey questions that asked respondents to identify SCPs received 483 responses, of which 148 (31%) addressed materials recycling/reuse. Interview subjects often addressed materials recycling/reuse when asked open-ended questions about SCPs. • In a competitive bid environment, contractors are likely to implement SCPs that directly reduce their costs or help them make money; other practices must be compensated for by the owner. This sentiment was expressed by multiple contractors in the interviews and workshop. All SCPs can be beneficial at some level: sometimes the contractor is the direct recipient of that benefit, while at other times some other entity benefits (e.g., owner agencies, public users, neighbors, and stakeholders). For those practices that directly benefit contrac- tors, owners need only to allow (or not specifically forbid) such practices for them to occur. For example, use of reclaimed asphalt pavement (RAP) in asphalt pavement can save a contractor money and is allowed, but not required, by an owner. However, if a contractor incurs costs for an SCP and benefits accrue to other entities, then a contractor is not likely to adopt that practice for fear of losing money or losing a bid because of the added costs with no accompanying benefits to them. In these instances, if an owner wants the benefits of the SCP, then the owner must specify what they wish to happen, and pay the contractor to offset their costs, or reward the contractor in some other way (e.g., points in best-value procurement). • The competitive advantage resulting from implementing a new SCP is short lived. Several contractors discussed this in the interviews. If an SCP can make a contractor more competi- tive in the bidding process, it is not long before competitors adopt the same practices and eliminate the advantage. While this may be viewed as positive for sustainability (instead of a select few, everyone is using the practice), it can also be viewed as a deterrent to early adop- tion by contractors. • SCPs tend to work when used. From 337 survey respondents, 53 instances of SCP failure were recorded. Many were singular instances of failure (e.g., de-bonded latex modified con- crete for a bridge deck overlay) that may or may not be repeated with more experience, while others were likely more common (RAP, recycled asphalt shingles, porous/pervious surfaces, warm mix asphalt). In general, the highway industry is conservative in implementing new practices, likely because of the perception and experience that failures (and their costs) are

14 Sustainable Highway Construction Guidebook not tolerated by the public and also overriding legal concerns. Thus, owners tend to require extensive testing, trials, and even guarantees before implementation, all of which contribute to reduced failure rates. • The performance of alternative materials/methods is addressed in relation to the current standard practice. This sentiment was expressed several times in the survey, interviews, and workshop. For instance, if current asphalt pavement surfacing is expected to last 15 years, the value of an alternative surfacing (open-graded friction course, thin overlay, rubber asphalt, bonded concrete wearing course) is determined based on how its projected service life com- pares to the standard 15 years. While this may be a narrow view since it does not consider added benefits (e.g., less tire-pavement noise, better drainage, lower carbon footprint), the most common sentiment is that alternatives must perform equal to or better than the current standard practice.