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Sustainability Impact Factor Areas make good use of available materials. The
primary focus of this area is to consider the
Measuring environmental sustainability is an reduced need for virgin material usage and
emerging field in the transportation industry, and demand of virgin materials for treatments.
even more so with respect to the pavement mainte- Many maintenance treatments involve in-place
nance treatment selection process. The literature is recycling, which enables re-use of the materi-
rife with newly coined terms to describe a given als already committed to roadways. Prolonging
treatment's impact on the environment (Takamura the time between major rehabilitation and
et al. 2001; James 2006; Ball et al. 2008; Chaignon reconstruction through proper pavement treat-
and Mueller 2009; Lane 2010; Muench 2010). "The ment selection is an effective way to reduce vir-
terms `Green,' `Sustainable Development,' `Environ- gin material usage.
mental Impact,' `Energy Efficiency,' `Global Warm- 2. Alternative material usage examines the oppor-
ing,' `Greenhouse Gases,' and `Eco-efficiency,' are tunity to recycle materials and to use other
becoming more widely recognized . . . " (Chehovitz materials in the pavement structure during
and Galehouse 2010). preservation and maintenance. This could
Unfortunately, each article or manual focuses its mean incorporating reclaimed asphalt pave-
evaluation of environmental impact on a different ment, recycled concrete aggregate, recycled
set of impacts. For example, Takamura et al. (2001) asphalt shingles, recycled rubber tire, glass, or
coined the term "eco-efficiency" to describe the com-
any other materials that might be appropriate.
parative analysis of six parameters: virgin material
Proper processing of these materials can result
consumption, energy consumption, land use, emis-
in equivalent performance to virgin aggregate
sions, toxicity, and risk potential. Pittenger's research
(Infraguide 2005). Careful blending and
(2010) included virgin material consumption, life-
crushing of recycled materials is required to
cycle cost, and a factor from the Greenroads certifi-
achieve consistent gradation and performance
cation program (Muench 2010); whereas Chehovitz
of the material (Infraguide 2005).
and Galehouse (2010) confined their analysis to
3. Programs for Pavement In-Service Monitoring
greenhouse gas emissions and energy consumption.
and Management assists agencies in finding the
Thus, it is difficult to adopt a single, universally rec-
right treatment for the right pavement at the
ognized term to identify the process of evaluating
right time. Robust information systems help
competing pavement preservation and maintenance
determine existing and forecasted pavement
treatment options on the basis of relative environ-
conditions so that decisions can be accurately
mental sustainability.
made and funds programmed for network
The AASHTO Center for Environmental Excel-
improvements. Pavement in-service monitor-
lence (CEE) provides a basis for identifying and pro-
ing and management would consider the life-
moting environmental excellence in the efficient
cycle and associated serviceability of the
delivery of transportation services (Kober 2009). The
treatment.
CEE evaluates sustainability parameters by identify-
4. Noise is defined as the unwanted or excessive
ing focus areas. Consequently, seven sustainability
sound associated with pavement construction
impact factor areas identified by the CEE will be con-
and improvements. Studies show that the most
sidered in this synthesis. Each one of the areas and
pervasive sources of noise in the environment
how they relate to pavement preservation and main-
relate to transportation. Therefore, noise is
tenance treatments is described herein. It should be
examined as an environmental sustainability
noted that other life-cycle assessment tools such as
factor area whereby pavement preservation and
the ISO 14040 Standard are available and many of
maintenance treatments are evaluated on their
these do cite other environmental sustainability
noise impacts (CEE 2010a).
impact factors (ISO 2006). However, for the purpose
5. Air quality/emissions examines six principal
of this synthesis, the seven aforementioned factors
air pollutants, namely carbon monoxide, lead,
have been examined and are described here.
nitrogen dioxide, ozone, particulate matter, and
1. Virgin material usage examines reducing the sulfur dioxide (CEE 2010b). The intent is to
need to use nonrenewable resources. Pavement assess each pavement preservation and main-
materials can be expensive and some resources tenance treatment in terms of these pollutants.
may be limited; therefore, it is important to This would involve both calculations for the
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