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Lew, Anderson, Muench 1

Informing Roadway Sustainability Practices Using Greenroads®

Certified Project Data

James B. Lew, M.Sc., E.I.T. (corresponding)

Department of Civil and Environmental Engineering, University of Washington

University of Washington, Box 352700, Seattle, WA 98195-2700

Tel: (415) 999-0007; E-mail: [email protected]

Jeralee L. Anderson, Ph.D., P.E., LEED® AP

Greenroads International

17371 NE 67th Court, Suite B202, Redmond, WA 98052

Tel: (425) 376-0685; E-mail: [email protected]

Stephen T. Muench, Ph.D., P.E.

Department of Civil and Environmental Engineering, University of Washington

University of Washington, Box 352700, Seattle, WA 98195-2700

Tel: (206) 616-1259, E-mail: [email protected]

Total Word Count: 5068 words text + 9 tables/figures x 250 words (each) = 7318 words

TRR Paper number: 16-4844

Submission Date: November 15, 2015


ABSTRACT

The rapid growth in popularity of sustainable roadway certification systems suggests that a

holistic evaluation of rating systems and a retrospective examination of sustainable roadway

practices is warranted. Regardless of underlying sustainability definitions guiding any

transportation project rating system, literature reveals that there is little consensus on how rating

systems should ultimately weigh human, environmental, and economic needs relative to each

other. Using a unique dataset consisting of 28 Greenroads Certified Projects, this research is the

first effort to use documented project certification data to investigate the state of practice of

sustainability rating systems and sustainable construction practices.

Using quantitative and qualitative analyses, this study identifies and explores common

strategies employed by project teams to achieve sustainability under the Greenroads® Rating

System. This study argues that sustainable projects make a quantifiable difference in

performance compared to typical projects. However, projects which pursue independent third-

party sustainability certification should strategize their expectations and manage performance

expectations accordingly because this research shows self-evaluations overestimate final

scores by an average of 15%. Although the Greenroads framework allows for many

combinations of scores, Certified Projects exhibit similar score breakdowns to both the Rating

System and other Certified Projects. Because the majority of points awarded by Greenroads is

limited to a subset of core credits, this study proposes that sustainable practices largely revolve

around current standards of practice, perceived practicality, or economic benefits. Future

research should focus on identifying similar patterns in other roadway sustainability rating

systems to explore the gap between sustainable knowledge and practice.


INTRODUCTION

Prevailing Trends in Sustainable Roadway Construction

Sustainability certification for roadway projects are motivated by desires to create benchmarks,

track or evaluate performance, foster branding or a reputation of accountability, or promote

construction best practices (1, 2). As political interests grow over the implications of climate

change, sustainability ratings also provide a medium to inform, communicate, and facilitate

business decisions with stakeholders (3, 4).

Roadway certifications can be voluntarily pursued by both private companies and public

transportation agencies for all levels of government (state, metropolitan, regional, local) (2, 5).

The evolution of sustainability rating systems parallels the growth of federal regulations on

sustainable development (2), now increasingly accepted as self- or 3rd-party evaluation tools

complementary to construction standards (6). Independent 3rd party evaluations are consequently

regarded as a more objective form of branding (2) and can distinguish the project, team, and

stakeholders as a purveyors of leading-edge sustainable transportation infrastructure.

While there is consensus that sustainability values are important, organizations struggle with the

specific integration of sustainable activities in planning and design (1, 2). Sustainability-related

exercises such as Life-Cycle Assessment and Life-Cycle Cost Analysis are often excluded from

practice due to knowledge gaps or uncertainty, particularly if unaligned with required standards

or perceived as economically infeasible (2). Anderson and Muench found that self-identified

sustainable roadway projects consistently scored higher than a typical project when using the

Greenroads Rating System as a metric for sustainability, implying that sustainable roadways can

successfully exceed existing construction standards while balancing economic considerations (6).

Essential Characteristics of Sustainability Rating Frameworks

A sustainability rating framework provides a collection of best practices in sustainable project

delivery (including design and construction), providing a structure to assess, measure, and

compare the performance of projects (6–8). Currently 12 sustainability rating systems

specifically may be applied to roadways although less than half have reached maturity in terms

of application or prominence (9, 10). Veeravigrom applied 11 assessment criteria identified by

Muench et. al. (7) to these rating systems and found that they satisfied most criteria aside from:

scope, weighting, substantiation, and degree of maturity (9). The following list collects common

mechanics and characteristics of existing sustainability rating frameworks in that they:

• address a time horizon (present and future) and a scope of physical application (project or

neighborhood), resulting in different data and documentation requirements (1).

• are comprised of best practices in sustainable construction

• include a sustainability paradigm or definition based on core elements of the Brundtland

Commission, the ‘Triple Bottom Line’, the ‘Reduce-Reuse-Recycle’ campaign, Robért’s

‘Natural Laws’, or a hybrid of the former (1, 7, 11–13).

• divide sustainability into credits (indicators) grouped thematically into credit categories

(dimensions) and type (required, voluntary, or custom/innovation) (14).

• are weighted or unweighted: in a weighted system, projects receive weighted scores

(points) to represent the relative value that the system places on certain practices (4),

whereas an unweighted system means all credits are equal in value.

• contain credits that address at least one of three fundamental dimensions of sustainability:


human, environment, and economics (2, 9, 7, 14, 15); and, any combination of life-cycle

phases (including operations, maintenance, and construction), but predominantly

planning and design and rarely decommissioning (2, 3).

In this research, the ‘sustainability scope’ refers to the relative weight of credit categories within

a rating system or a particular project. The sustainability scope provides a higher resolution than

a final score, intending to capture the breadth and extent of sustainability implemented by a

project (12, 14).

General Comparison of Roadway Sustainability Rating Systems

There is no consensus on an accepted list of indicators (often referred to as credits) that

comprehensively encompasses the breadth of sustainability, let alone an accepted metric for

framework effectiveness in terms of actual project performance (10, 16–18). Nevertheless,

transparency, practicality, and usability are commonly cited as desirable qualities of rating

systems (1, 9, 18).

Several studies explore different sustainability credit categories, offering their own list of

sustainable credit to represent their perceived sustainability scope (4, 5, 7, 10). Ramani et. al.

found that the sustainability scope of projects did not vary significantly when disaggregated into

and rated as smaller road segments (1). Applying their Global Framework, Muench et. al.

contributed three important observations: (1) the sustainability scope of projects exhibited little

variation relative to each other, (2) the scope of the projects strongly resembled that of the

overarching systems and (3) the sustainability scope did not vary substantially between rating

systems (14). Their research suggests that rating systems and their projects prioritize human,

environmental, and economic themed credits in a similar manner.

Despite the abundance of new rating systems, literature suggests that credits and categories are

still commonly missing from or inadequately addressed in frameworks. These topics include but

are not limited to: context sensitivity (5), administration (13), stakeholder involvement (11),

documentation (10), security (2), customization credits / innovation (8), and education (5).

Though undisputed in importance, economic-themed credits are consistently underrepresented in

frameworks compared to environmental and human themed credits (8, 9). Veeravigrom observed

that most rating systems are created by developed countries (9), suggesting a different country

may weight credits differently or otherwise include or exclude credits based on their perceived

sustainable value. That is, regulation already dominates best practices for social and economic

policy in developed countries so economic-themed credits may be redundant to include in the

rating systems. Meanwhile, developing countries may value environmental policy and socio-

economic development more heavily and choose to include more credits which address these

themes (or weight existing ones more heavily). In other words, the perspective that credits are

considered under-represented in a framework is subjective and depends on the context (or

country) in which the framework is applied.

RESEARCH SCOPE AND OBJECTIVES

This research identifies performance trends among Greenroads Certified Projects to investigate

how project certification data from a particular sustainability rating framework can inform the

state of practice of roadway sustainability certification. The analyses used in this research


explore behavioral patterns among Greenroads Certified Projects to characterize prevailing

perceptions of how sustainability is interpreted by project teams compared to the rating system

itself. Specifically, this study applies four analyses to address the following objectives:

(1) compare the contribution of individual credits and credit categories across projects,

(2) analyze the relative timelines of construction and the certification process,

(3) determine the sustainability scope of projects and profile a typical Certified Project,

(4) investigate the change between the initially expected and final certification scores.

These analyses compare the sustainability performance of Certified Projects as defined by the

Greenroads Rating System. Furthermore, this study can potentially help rating systems evaluate

themselves to identify misconceptions and improve framework usability and transparency.

METHOD

This section provides a description of the Greenroads Rating System, a brief description of data

and data quality, and an explanation of involved analyses. The Greenroads Foundation has

provided data for all 28 projects currently certified using the Greenroads Rating System v1.5.

The data set generally consists of an initial expected score and a final project score broken down

into 46 credits and 6 credit categories (Table 1).

State of Practice of the Greenroads Rating System (v1.5)

The Greenroads Rating System is a voluntary 3rd party project certification program administered

by the non-governmental organization Greenroads International. Teams registering a project are

expressing an actionable intent to incorporate sustainability by removing the inherent bias of

self-evaluation. Since each credit is substantiated by project documentation and assessed

independently using the same criteria for each project, projects believe that Greenroads produces

meaningful measures of sustainability performance to validate these intentions. The authors

therefore propose that the project data is of high quality and represents a population of projects at

the forefront of state-of-the-art sustainable roadway construction.

There is room for improvement even amongst Greenroads Certified Projects: no Greenroads

Project has achieved more than a Silver rating (46 points of 118 possible) and no roadway rating

system to date offers a detailed evaluation of their certified project performance scores. By

focusing specifically on certified project data, this study is first to analyze a unique population

data set regarding the performance of sustainable roadways.

Table 1 summarizes the minimum requirements, credits, and points allocated to each voluntary

activity in the Greenroads Rating System. Each category can be associated with a different

project life-cycle phase or aligned with a professional most likely to be interested in the

performance measures in the category. So, the Greenroads Rating System provides several

perspectives to view the rating system’s structure.

Table 2 summarizes the quantitative performance scores and the extent of sustainability achieved

by each project and Table 3 provides qualitative information on Certified Projects. Additional

data for project background includes (but is not limited to) key milestone dates for construction

and certification, project value and size, and general location information.


Data Inclusion and Interpretation

Project Requirements

Project Requirements are considered in the credit analysis because their mandatory achievement

contributes substantially to the sustainability of a project, particularly because they include

activities not normally considered standard practice. However, they are excluded from analyses

involving Greenroads certification scores because they do not contribute points.

Custom Credits

Despite being classified as a separate category, custom credits may relate to any existing credit

category in the Greenroads rating system. In separate cases, custom credits are included and

excluded from analyses to investigate whether this impacts how sustainability is measured.

However, it is critical to note that custom credits were gradually added to the rating system as

they are developed by Greenroads. So, not every project received an equal opportunity to achieve

a custom credit and subsequent analysis is substantially limited in interpretation.

Weighting: Credits versus Points

Greenroads credits are assigned points to indicate their relative importance and value with a

range of 1-5 points per credit (Table 1). This yields two bases to analyze the rating system: ‘by-

Points’ earned (weighted) or ‘by-Credits’ achieved (unweighted). A by-Credit basis projects a

binary acknowledgement of achievement whereas a by-Point basis expresses the extent of an

achievement according to the Greenroads Rating System.

Project Milestones

Although other project milestones exist, this research assumes that the project application date

denotes the beginning of a contractual relationship between Greenroads and a project team. The

project application date is intended to approximate the point in a project life-cycle that a project

team would likely begin to engage in Greenroads-related activity. While administratively

determined dates do not always correspond with actual work, the application date is still the best

available proxy for actual work dates.

Expected/Final Scores

A project team establishes an expected score at project registration based on their interpretation

of how sustainability is integrated. A project team calculates their expected score by identifying

the credits which they believe are achievable and best align with the project’s intentions. As the

project progresses the project team receives feedback on each pursued credit from Greenroads

International, who then indicates what additional activities or documents will be necessary to

achieve the credits. The project is audited after construction is completed and the project receives

an independent 3rd party final score upon certification. Any comparison of expected and final

scores is limited to totals scores and final award level.

Related Certified Projects

Projects 4, 5, 6, and 9 are separate projects registered by the City of Tacoma, and Projects 12-16

(SFPR), Projects 18-20 (Presidio Parkway), and Projects 23-26 (CBD Raingardens) represent

three Greenroads Programs with multiple phases or segments; each certified separately as a

“Project.” For Programs, individual project value was calculated using the total project value and

dividing it evenly over the total lane miles for each project. For example, SFPR (1.23 billion


CAD) was divided over 5 segments proportionally by lane-miles. The same is done for other

Projects, i.e. Presidio Parkway (projects 18-20) and CBD Raingardens (projects 23-26). SFPR

and Presidio Parkway projects are currently the only highway projects certified with Greenroads.

Analytical Approach

Analysis 1: Cumulative Credit Contribution

The goal of Analysis 1 is to determine which credits contribute most to cumulative points ever

awarded and individual project scores. The cumulative score of each credit’s contribution

indicates which credits are most frequently pursued and awarded by Greenroads (or conversely,

not at all).

Analysis 2: Construction and Certification Timelines

Analysis 2 explores typical procedural behavior for Greenroads Certified Projects by examining

the relative positions of construction and certification start and end dates. By doing so, this

analysis observes the relationship between the two timelines, which may potentially impact

project performance.

Analysis 3: Expected versus Final Project Scores

Project overshoot is defined as the margin between the expected score prior to certification (i.e.

at application) and the final score received upon certification. This goal of Analysis 3 is to

identify patterns in overshoot, including factors that may influence the magnitude of overshoot

and ultimate level of achievement.

Analysis 4: Project and Sustainability Scope

Analysis 4 compares the sustainability scope (the relative contribution of each credit category) of

projects to the overarching scope of the Rating System. The weighting of a rating system is not

necessarily representative of how a specific project will weigh the credit importance when

planning or designing. Whereas the system’s weights represent Greenroads’ perception of

sustainability, the final project scores represents the project team’s interpretation of how

sustainability is implemented. In this study, the differences in sustainability scope between the

overarching rating system and the final project scores is interpreted as a gap between how

sustainability is perceived versus implemented.

RESULTS

This section presents and interprets the results as they would pertain to both the Greenroads

rating system and by extension, the sustainable roadway industry.

Analysis 1: Cumulative Credit Contribution

Figure 1a ranks and sorts the credits by aggregated contributions to the cumulative total points

awarded by Greenroads. Figure 1b shows the difference between two methods of counting

contribution (by-Points verses by-Credits) as a running total percentage of points or credits

earned, with credits listed in order of point contribution. The difference between ranking credits

by-Points or by-Credits is due to credit weighting: more points per credit implies a greater

variance in possible achievement levels. The curves would be identical in an unweighted system.

Several important observations arise from the figures:


• Figure 1a shows only 8 credits are responsible for 50% of credits ever awarded: AE-3,

MR-5, PT-1, EW-5, MR-6, PT-4, AE-2, and AE-5

• 9 voluntary credits (including 4 CC) were never achieved (about 20% of available

credits)

• The AE category holds 3 of the top ten contributing credits including AE-3 which was

achieved by all Certified Projects.

The results suggest that the highest contributing credits are those which are common practice: for

example, intelligent transportation solutions (AE-2), context sensitivity (AE-3), pedestrian access

(AE-5), and site-vegetation (EW-5). Otherwise, oft achieved credits are those that seem to

present a commonly accepted cost/benefit advantage: energy efficiency (MR-6) which may

reduce lifetime energy consumption, and regional materials (MR-5) which can reduce emissions

and transportation distances for materials. PT-1 and PT-4 appear related because there are some

overlapping requirements, often leading to their joint achievement.

Similarly, the non-achievement of 10 credits may potentially be attributed to:

• Credit practices are perceived as economically infeasible or impractical to achieve, such

as biodiesel usage and associated equipment availability (CA-4, CA-5, PT-5)

• Some credits are written with unclear objectives and lead to credit misinterpretations,

such as performance tracking (PT-6) and emissions reduction (AE-4)

• Credits do not align with an agency’s strategic goals such as habitat restoration (EW-6)

• Custom credits may not have been existed at the time of a specific project’s certification;

this is evidenced by the achievement rates for CC-1 as projects progress

If only 8 credits comprise 50% of all project scores, this suggests that sustainable practices have

room for growth. Because most Certified Projects pursue the core list of 8 credits, project teams

can distinguish their projects by the achievement of less-frequently pursued credits. For example,

2 credits (MR-1, EW-7) have only been achieved once, by separate projects, and not at full

value. Similarly, such results identify sustainable practices which are commonly perceived as

impractical or prohibitively expensive by project teams. Another explanation is that credits with

low achievement rates result from the lack of transparency in the credit descriptions or

misinterpretation by project teams. Finally, the results may also draw attention to barriers to

achievement such as lack of supporting infrastructure, knowledge, or experience.

In an extensive case study, Anderson and Muench rated 105 projects post-construction using the

Greenroads system and divided the results into ‘sustainable’ and ‘typical’ roadway projects,

finding that significant differences existed between the two project score sets (6). This research

assumes that a higher score implies a more sustainable project, recognizing that projects may

score differently under alternative systems. Expanding upon their work, this study applies a

statistical analysis (student’s t-test) to compare the credit achievement rates of Certified Projects

(28) presented in this paper to both the sustainable projects (45) and typical projects (60)

identified by Anderson and Muench.

A hypothesis test comparing certified and typical project data implied the difference was

significant with a confidence of 96.8% (p = 0.032). Meanwhile the test comparing Certified

Projects to sustainable projects was less conclusive, implying a difference with only 83.6%


confidence (p = 0.154). Further analysis using Cohen’s d test reveals an effect size of 0.33

(small/moderate) for Certified Projects versus sustainable, and 0.51 (moderate/large) for

Certified Projects versus typical projects. Collectively, these statistics imply that Certified

Projects exhibit a clear difference compared to typical projects in their performance and

implementation of sustainability.

Analysis 2: Construction and Certification Timelines

Figure 2 depicts the relative positioning of construction and certification windows, shedding

light on when a project begins to integrate sustainability into a roadway project. 17 of 28 projects

applied for certification with Greenroads prior to the reported beginning of construction; of

these, 1 project applied for certification more than a year prior to construction.

While best practices in integrated project delivery suggest that bolstering pre-engineering

(planning and development) will result in more effective project implementation while

simultaneously reducing the cost to otherwise achieve such impact (19), no substantial evidence

of this has been seen in Greenroads yet. Of the 17 projects which applied before construction

began, about 41% (7 projects) achieved a Silver rating, compared to only 18% (2 of 11 projects)

which applied after construction. This could mean that earlier engagement leads to higher scores,

or other factors may be influencing this observation: e.g. projects more likely to score higher

coincidentally applied for certification earlier coincidentally.

Analysis 3: Expected versus Final Project Scores

Table 4 shows the magnitude of overshoot (defined as the final certified score subtracted from

the project team’s initial expected score). Observations are:

• All final scores are less than expected scores

• Six projects (22%) encountered a reduction in award level between expected and final

Certified Project score and all six project teams expected to achieve a Silver rating or higher

• The average project overshoots their final score by 15% or about 6 points (2-3 credits),

but this percent overshoot is not strongly correlated to the final award level achieved.

• Percent overshoot does not seem to be related to experience level with the rating system,

as Projects 4, 6, 7 and 9 have the same lead designer yet exhibited inconsistent levels of

overshoot.

• Neither project size nor value has a clear correlation with % overshoot.

Analysis 4: Project and Sustainability Scope

The sustainability scopes for all Certified Projects and the average Certified Project is

summarized in Table 5, aggregated by credit category presented in Figure 3. There are two ways

of profiling a typical Greenroads Project: by the average achievement rate or based on the

category breakdown of combined scores. Table 4 shows that these profiles exhibit a similar

category distribution, implying that the score breakdown of a typical project is similar to the

scope of all Certified Projects combined. Several observations can be made from these figure and

table:

• A typical Certified Project relies primarily on 3 credit categories for the majority of their

points: AE (32%), MR (21%), and EW (18%) in terms of total contribution

• AE is consistently the most pursued credit category; CA and PT credit are the least.


• The average project will earn 1 custom credit worth 2 points, indicating that custom

credits contribute consistently to most project scores

• All but 4 projects pursued at least one custom credit

Figure 4 illustrates how the credit category breakdown (i.e. sustainability scope) changes

depending on whether credits or points are counted, and whether custom credits are included.

The Project Requirements category is excluded because they are pre-requisites to certification

and contribute no points.

Observations are:

• Although small variation exists for some credit categories between project, projects

generally appear to reflect the sustainability scope of the overarching system itself

• The above observation appears true regardless of whether custom credits are included and

whether performance is viewed a weighted or unweighted basis

• The contribution of the CC category appears just slightly higher than the actual

performance of projects. However, since custom credits are developed over time and eventually

incorporated into the system, not all project had access to the same custom credits.

• On a per credit basis for project performances, PT and CC are achieved at roughly the

same levels. This may imply that either custom credits are important to include because they

contribute comparably to a primary credit category or that the PT category is too narrowly

scoped, adding a material and pavement bias to the system.

DISUCSSION AND CONCLUSIONS

This paper demonstrates how project certification data can be used to inform the state of practice

of roadway sustainability rating systems. The evaluation of sustainability rating systems is a

growing field that generally suffers from a clear lack of consensus of how sustainability should

be measured. Consequently, sustainability should be examined as an approach as well as a

characteristic of a project. By highlighting key indicators from certification data, this paper

provides a direction to guide the evaluation and comparison of rating systems. In particular, the

analyses employed in this research have led to the following set of conclusions and

recommendations:

Cumulative Credit Contribution

Projects tend to pursue sustainable roadway practices that strongly align with existing standards

of practice and are perceived as having a clear economic benefit. Consequently, projects rely

heavily on 3 credit categories (AE, MR, EW) and a core list of 8 credits for over half their

achieved score. However, a student’s t-test reveals that Certified Projects exhibit a statistical

difference in sustainability achievement over typical projects, implying that this difference is

manifested through the achievement of project requirements and credits beyond the core list.

Construction and Certification Timelines

Over half (17 projects) of the project teams submit an application for certification with

Greenroads prior to beginning construction, a common best practice recommendation for

integrated project delivery (19). These projects exhibit higher average scores and achieve a

Silver rating more frequently than projects which apply after the beginning of construction, but

this may be a coincidence. One explanation is that roadway certification itself is not currently


common practice and presents more procedural obstacles to application (adequate funding,

approval from superiors, learning curve). Finally, project teams which apply for certification

after project construction may not fully appreciate that roadway certification systems award

points based on engineering effort in the planning and design phases in addition to the project

performance.

Expected versus Final Project Scores

Project teams generally expect to earn more points than their final score indicates by 15%

on average, implying that self-evaluations tend to be overly optimistic compared to an

independent 3rd party rating. This statistic highlights the inherent bias of self-evaluation and

suggests that project teams should temper expectations when establishing an expected score.

Project teams pursuing sustainability certification should be aware that self-assessments tend to

be overly optimistic and evaluate their own capacity to achieve based on the following criteria:

(1)Data and Documentation: Does the team have a system for collecting and managing data

required for documentation; how much effort does data collection and documentation require?

(2)Interpretation – How well are the rating system and credit objectives understood and

interpreted by a project team?

(3)Experience – Do project team members or contractors have previous experience with

roadway certification systems like Greenroads?

(4)Contextualization – Are credits pursued consciously (and at the appropriate time) with an

intent to implement sustainability or are there confounding factors such as economic practicality?

Project and Sustainability Scope

This research shows that teams tend to consider a small subset of credits, resulting in project

scores that do not vary substantially in their scope compared to the fixed system scope. Despite

the apparent flexibility and potential existence for large score variations in sustainability scope

between projects, the findings of this research suggests that the sustainability scope of Certified

Projects is similar to the overarching Greenroads Rating System. Furthermore, it is unlikely that

a project team can pursue a subset of credits that will result in a sustainability scope radically

different than the rating system. The result both updates and reinforces the findings of Muench,

et al. (14). This study also reinforces the research of Veeravigrom in which she demonstrated

that, using the Global Framework, 11 Greenroads projects exhibited sustainability scopes similar

each other as well as to their overarching rating system (14). The results may imply that

sustainability scopes of projects may be limited by their overarching rating system and therefore

a certification award is a reflection of a particular rating system’s sustainability values.

The relative achievement rates of credit categories (e.g. AE vs CA) may suggest that current

project delivery practices favor conscious sustainability input by designers. This is because

designers may have a greater level of influence over the final product and earlier in the project

life-cycle compared to contractors, who are constrained by fixed project specifications.

Contractors and material suppliers participate in projects through standard specifications that are

unlikely to change, potentially explaining the high achievement of access and equity (AE) credits

and low achievement of construction themed credits (CA). The achievement of material resource

credits (MR) falls somewhere in between likely for economic reasons rather than conscious

sustainability-related decisions. Although the AE category is largely a human centric category,

the environmental category is the dominant theme for credits the Greenroads Rating System (12).


This suggests that projects are more likely to pursue human-themed credits despite the larger

selection of environmentally themed credit in the system. This is also noteworthy because AE

credits indicate a sustainable approach, but CA and PT credits directly impact the sustainable

performance of the physical road. A credit or indicator almost always address multiple

sustainability themes and their placement in one category or another is often for convenience or

perception (9, 10, 14). A credit may impact one or more category, and thus the category name

does not comprehensively indicative what a credit may address; this is an inherent issue of

category labels. It is difficult to compare custom credits because project teams had access to

different numbers of CCs as they were gradually added to the system.

RECOMMENDATIONS

There is room for improvement even amongst Certified Projects which this paper proposes are

representations state-of-the-art sustainable construction practices. The lack of Certified Projects

with award levels higher than Silver and the low achievement of more than half of available

credits evidences this. Nevertheless, the margin for improvement is a positive characteristic of

sustainability rating systems in general because their purpose should be to encourage projects to

exceed standards of practice.

Furthermore, if the average project performance gradually rises, the sustainability rating system

should also adjust to acknowledge that benchmarks for sustainability are becoming increasingly

standard practice. For example, accepted custom credits should be reclassified under appropriate

categories. Because credits pertain to multiple dimensions of sustainability, innovated credits

cannot be compared in a meaningful manner without a proper or substantiated sustainability

classification. A rating system credits at a nearly 100% achievement rate should consider making

such credits project requirements. Regardless of the rationale for pursuing a credit, near-

universal achievement indicates that a benchmark may be evolving into a common practice. In

other words, a Certified Project rating of Silver today could (and should) mean something

different a decade from now.

As definitions of sustainability continue to evolve, it is challenging to objectively rate the

sustainable performance achieved by a project using a single rating system at a given point in

time. Consequently, is important to compare the performances of certified projects from other

sustainability rating systems to determine whether trends presented in this paper are also present

in those rating system. To better understand the effects of credit weighting, future research may

explore how sensitive rating systems are to alternative weighting strategies. There is general

consensus that sustainability rating systems collect the best sustainable practices but less is

understood how the industry gradually incorporates sustainability into standards of practice.

Future research may address this gap, specifically identifying factors which impact a project

team’s willingness to adopt certain practices, such as misconceptions of sustainability, or the

appropriate timeframes required to successfully complete a rating system’s certification

activities.

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Rating Systems for Transportation and Neighborhood-Level Developments. Green Streets,

Highways, and Development 2013, pp. 337–354.

9. Veeravigrom, M. An International Framework for Sustainable Roadway Rating Systems.

PhD Dissertation. University of Washington, Seattle, 2015.

10. Clevenger, C. M., M. E. Ozbek, and S. Simpson. Review of Sustainability Rating Systems

used for Infrastructure Projects. Presented at the 49th ASC Annual International Conference,

San Luis Obispo, CA, 2013.

11. Jeon, C. M., and A. Amekudzi. Addressing Sustainability in Transportation Systems:

Definitions, Indicators, and Metrics. Journal of Infrastructure Systems, Vol. 11, No. 1, Mar.

2005, pp. 31–50.

12. Veeravigrom, M., S. T. Muench, and H. Kosonen. A Global Framework for Sustainable

Roadway Rating Systems. Presented at the Transportation Research Board 94th Annual

Meeting, 2015.

13. Amiril, A., A. H. Nawawi, R. Takim, and S. N. F. A. Latif. Transportation Infrastructure

Project Sustainability Factors and Performance. Procedia - Social and Behavioral Sciences,

Vol. 153, Oct. 2014, pp. 90–98.

14. Muench, S. T., H. Kosonen, M. Veeravigrom, and J. Yamaura. What They Want You to Do:

Identifying the Scope and Priorities of Roadway Sustainability Rating Systems. Presented at

the Transportation Research Board 94th Annual Meeting, 2015.

15. Veeravigrom, M., S. T. Muench, and H. Kosonen. Global Framework for Sustainable

Roadway Rating Systems. Aug. 2014.

16. Sitas, N., H. E. Prozesky, K. J. Esler, and B. Reyers. Exploring the Gap between Ecosystem

Service Research and Management in Development Planning. Sustainability, Vol. 6, No. 6,

Jun. 2014, pp. 3802–3824.

17. Muench, S., M. Scarsella, M. Bradway, L. Hormann, and L. Cornell. Evaluating Project-

Based Roadway Sustainability Rating System for Public Agency Use. Transportation


Research Record: Journal of the Transportation Research Board, Vol. 2285, Dec. 2012, pp.

8–18.

18. Atlee, J., and R. Kirchain. Operational Sustainability Metrics Assessing Metric Effectiveness

in the Context of Electronics-Recycling Systems. Vol. 40, Jul. 200

19. The Construction Users Roundtable. Collaboration, Integrated Information, and the Project

Lifecycle in Building Design, Construction and Operation. The Construction Users

Roundtable, Aug. 2004.


LIST OF TABLES

TABLE 1 Greenroads Rating System 1.5 Voluntary Credit Descriptions No. Title Pts. Description

Project Requirements (PR)

PR-1 Environmental Review Process Req. Complete an environmental review process

PR-2 Lifecycle Cost Analysis Req. Perform LCCA for pavement section

PR-3 Lifecycle Inventory Req. Perform LCI of pavement section with software tool

PR-4 Quality Control Plan Req. Have a formal contractor quality control plan

PR-5 Noise Mitigation Plan Req. Have a construction noise mitigation plan

PR-6 Waste Management Plan Req. Have a plan to divert C&D waste from landfill

PR-7 Pollution Prevention Plan Req. Have a stormwater pollution prevention plan

PR-8 Low-Impact Development Req. Study feasibility of LID techniques for stormwater

PR-9 Pavement Management System Req. Have a pavement preservation system

PR-10 Site Maintenance Plan Req. Have a maintenance plan for environment, utilities

PR-11 Educational Outreach Req. Publicize sustainability information for project

Voluntary Credits

Environment & Water (EW)

EW-1 Environmental Management System 2 Have ISO 14001 certification for general contractor

EW-2 Runoff Flow Control 3 Reduce runoff quantity

EW-3 Runoff Quality 3 Treat stormwater on-site

EW-4 Stormwater Cost Analysis 1 Conduct a LCCA for stormwater BMP/LID selection

EW-5 Site Vegetation 3 Use native low/no water vegetation

EW-6 Habitat Restoration 3 Create new habitat beyond what is required

EW-7 Ecological Connectivity 3 Connect habitat across roadways

EW-8 Light Pollution 3 Discourage light pollution

EW Subtotal: 21

Access & Equity (AE)

AE-1 Safety Audit 2 Perform roadway safety audit

AE-2 Intelligent Transportation Systems 5 Implement ITS solutions

AE-3 Context Sensitive Solutions 5 Plan for context sensitive solutions

AE-4 Traffic Emissions Reduction 5 Reduce air emissions systematically

AE-5 Pedestrian Access 2 Provide/improve pedestrian accessibility

AE-6 Bicycle Access 2 Provide/improve bicycle accessibility

AE-7 Transit & HOV Access 5 Provide/improve transit/HOV accessibility

AE-8 Scenic Views 2 Provide views of scenery or vistas

AE-9 Cultural Outreach 2 Promote art/culture/community values on roadway

AE Subtotal: 30

Construction Activities (CA)

CA-1 Quality Process Management 2 Have ISO 9001 certification for general contractor

CA-2 Environmental Training 1 Provide environmental training

CA-3 Site Recycling Plan 1 Provide plan for on-site recycling and trash

CA-4 Fossil Fuel Reduction 2 Use alternative fuels in construction equipment

CA-5 Equipment Emission Reduction 2 Meet EPA Tier 4 standards for non-road equip.

CA-6 Paving Emission Reduction 1 Use pavers that meet NIOSH requirements

CA-7 Water Use Monitoring 2 Develop data on water use in construction

CA-8 Contractor Warranty 3 Offer an extended warranty on pavement

CA Subtotal: 14

Materials & Resources (MR)

MR-1 Lifecycle Assessment 2 Conduct a detailed LCA of the entire project

MR-2 Pavement Reuse 5 Reuse existing pavement sections

MR-3 Earthwork Balance 1 Balance cut/fill quantities


MR-4 Recycled Materials 5 Use recycled materials for new pavement

MR-5 Regional Materials 5 Use regional materials to reduce emissions

MR-6 Energy Efficiency 5 Improve energy efficiency of operational systems

MR Subtotal: 23

Pavement Technologies (PT)

PT-1 Long-Life Pavement 5 Design pavements for long-life

PT-2 Permeable Pavement 3 Use permeable pavement as a LID technique

PT-3 Warm Mix Asphalt 3 Use WMA in place of HMA

PT-4 Cool Pavement 5 Use a surface that retains less heat

PT-5 Quiet Pavement 3 Use a quiet pavement to reduce noise

PT-6 Pavement Performance Monitoring 1 Relate construction to performance data

PT Subtotal: 20

Voluntary Credit Total: 108

Custom Credits (CC)

CC-1 Sustainable Transportation Professional 5

CC-2 Work Zone Safety 5

CC-3 Pavement Smoothness 5

CC-4 Roadside Revegetation (Pilot Credit) 5

CC-5 Electric Vehicle Infrastructure 5

CC-6 Alternative Energy 5

CC-7 Freight Access 5

CC-8 VOC Reduction 5

CC-9 Design for Disassembly 5

CC Subtotal: 10 Maximum allowed points

Greenroads Total: 118


TABLE 2 Source Data for Greenroads Project Scores

Project # 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28

EW-1 0 0 0 0 0 0 0 0 0 0 0 2 2 2 2 2 0 0 0 0 0 0 0 0 0 0 0 0

EW-2 1 1 2 3 3 3 0 3 3 2 0 0 0 0 0 0 0 0 0 0 0 3 3 3 3 3 1 3

EW-3 2 0 0 1 3 3 0 0 3 0 0 0 0 0 0 0 0 0 0 0 0 3 3 3 3 3 2 1

EW-4 0 0 0 1 1 1 0 0 1 1 0 1 1 1 1 1 1 0 0 0 0 0 1 1 1 1 0 0

EW-5 1 1 1 3 2 3 0 2 3 1 1 3 3 3 3 3 2 3 3 3 3 2 3 3 3 3 2 2

EW-6 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

EW-7 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0

EW-8 3 3 3 0 0 0 3 0 3 0 3 0 0 0 0 0 3 0 0 0 3 0 0 0 0 0 0 0

AE-1 0 0 0 0 0 0 0 0 0 0 0 2 2 2 2 2 0 1 1 1 0 0 0 0 0 0 0 0

AE-2 0 0 4 0 5 0 2 2 0 0 4 0 0 0 0 0 3 4 4 4 3 3 0 0 0 0 3 3

AE-3 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5

AE-4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

AE-5 2 2 2 2 2 1 1 2 2 2 2 0 0 0 0 0 2 1 1 1 2 2 2 2 2 2 2 2

AE-6 2 1 1 1 2 0 0 0 0 2 2 1 1 1 1 1 2 1 1 1 2 1 0 0 0 1 1 1

AE-7 0 0 0 0 2 0 0 0 0 0 2 0 0 0 0 0 2 2 2 2 1 2 0 0 0 0 0 5

AE-8 2 0 0 0 2 0 1 2 0 0 1 0 0 0 0 0 0 2 2 2 0 0 0 0 0 0 0 0

AE-9 0 2 2 0 0 0 1 2 0 2 2 1 1 1 1 1 0 1 1 1 0 0 0 0 0 0 2 2

CA-1 0 0 0 0 0 0 0 0 0 0 0 2 2 2 2 2 0 0 0 0 0 0 0 0 0 0 0 0

CA-2 0 1 0 0 1 1 0 0 1 0 1 1 1 1 1 1 0 0 0 0 1 1 0 0 0 0 1 0

CA-3 1 1 0 1 1 1 1 1 1 0 1 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1

CA-4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

CA-5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

CA-6 0 1 0 1 1 1 0 0 1 0 1 1 1 1 1 1 0 0 0 0 0 1 0 0 0 0 0 0

CA-7 2 2 0 2 0 2 2 2 2 2 2 0 0 0 0 0 0 0 0 0 2 2 2 2 2 2 2 2

CA-8 0 0 0 0 0 0 0 3 0 3 0 3 3 3 3 3 0 0 0 0 0 0 0 0 0 0 0 0

MR-1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 0 0 0 0 0 0 0 0

MR-2 4 0 0 0 0 0 5 0 0 0 0 0 0 0 0 0 0 0 0 0 5 0 5 5 5 5 0 0

MR-3 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

MR-4 3 2 0 0 5 0 1 2 0 1 0 0 0 0 0 0 0 0 0 3 1 1 3 3 3 3 0 0

MR-5 5 4 0 5 5 5 1 4 5 1 3 5 5 5 5 5 3 0 0 0 5 5 4 4 4 4 5 5

MR-6 3 4 5 5 0 0 5 3 4 0 5 0 0 0 0 0 5 0 0 0 3 4 0 0 0 0 5 0

PT-1 5 5 0 0 0 0 5 5 0 5 0 0 0 0 0 0 5 5 5 5 5 5 0 0 0 0 0 5

PT-2 3 0 3 3 3 3 0 0 3 0 0 0 0 0 0 0 2 0 0 3 0 0 0 0 0 1 0 0

PT-3 0 3 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 0 0 0 0 0 0 0

PT-4 0 0 5 5 0 5 0 5 5 5 0 0 0 0 0 0 0 5 5 5 0 0 0 0 0 0 5 5

PT-5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

PT-6 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

CC-1 0 0 0 0 1 1 0 0 1 0 1 1 1 1 1 1 0 1 1 1 1 1 1 1 1 1 1 1

CC-2 0 0 0 0 0 1 2 0 2 0 2 2 2 2 2 2 0 0 0 0 0 0 0 0 0 0 0 0

CC-3 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

CC-4 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 0

CC-5 0 5 0 5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

CC-6 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

CC-7 0 0 0 0 0 0 0 0 0 0 2 2 2 2 2 2 0 0 0 0 0 0 0 0 0 0 0 0

CC-8 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

CC-9 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Project # 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28

Final Score 44 43 33 43 44 36 35 45 45 32 40 32 32 32 32 32 35 33 33 39 46 43 33 33 34 36 38 43

Credits Achieved 16 17 11 15 17 15 14 17 17 13 18 15 15 15 15 15 12 14 14 16 17 18 12 12 13 15 15 15


TABLE 3 Project attributes for 28 Certified Greenroads Projects

# Project Name

State or

Province

Month of

Construction

Completion

Month of

Certification

Date

0M 100M 200M 300M 400M

Project Value

0 5 10 15 20 25 30

Lane Miles

1 Meador Kansas Ellis Trail WA 9/2011 2/2012

2 Southeast Pioneer Way Reconstruction WA 10/2011 4/2012

3 South Division Street Promenade WA 12/2011 4/2012

4 Cheney Stadium Sustainable Stormwater Project WA 12/2011 4/2012

5 Alaska Street Improvements WA 2/2012 12/2012

6 Asotin Court WA 2/2012 1/2013

7 2010 STP Monterey Road Rehabilitation CA 10/2011 7/2013

8 Bagby Street Reconstruction TX 7/2013 10/2013

9 Wapato Lake Drive WA 2/2012 11/2013

10 14th Street: Market to Colfax CO 12/2011 3/2014

11 Transportation Gateway: S 216th Street WA 12/2013 6/2014

12 *SFPR: Terminus in Delta to HWY-99 Interchange BC 12/2012 8/2014

13 *SFPR: HWY-99 Interchange to HWY-91 Connector BC 12/2012 8/2014

14 *SFPR: HWY-91 Connector to Delta/Surrey Border BC 12/2012 8/2014

15 *SFPR: Delta/Surrey Border to Port Mann Bridge BC 12/2012 8/2014

16 *SFPR: Port Mann Bridge to Terminus in Surrey BC 12/2012 8/2014

17 Bristol Street Widening Phase II CA 6/2014 11/2014

18 *Presidio Parkway: Ruckman Bridge Replacement CA 12/2012 12/2014

19 *Presidio Parkway: Southbound High Viaduct CA 12/2012 12/2014

20 *Presidio Parkway: Southbound Battery Tunnel CA 12/2012 12/2014

21 NE 120th Street Extension WA 11/2012 4/2015

22 SR 522 Bothell Crossroads WA 9/2014 4/2015

23 *CBD Raingardens: Unity Street WA 3/2014 8/2015

24 *CBD Raingardens: York Street WA 3/2014 8/2015

25 *CBD Raingardens: Champion WA 3/2014 8/2015

26 *CBD Raingardens: Magnolia WA 3/2014 8/2015

27 SR 527 Multiway Boulevard Phase I: West Side WA 7/2014 8/2015

28 Smokey Point Transit Center WA 5/2014 8/2015

$0.89M 0.63

$4.25M 0.42

$3.17M 0.38

$0.92M 0.82

$4.08M 2.20

$0.48M 0.22

$2.68M 8.25

$9.60M 1.22

$1.16M 0.50

$9.27M 0.50

$5.18M 1.60

$285.86M 20.85

$252.13M 18.39

$156.73M 11.43

$320.27M 23.36

$144.91M 10.57

$52.20M 3.60

$76.92M 1.01

$110.43M 1.45

$308.45M 4.05

$6.72M 0.33

$15.20M 1.68

$0.10M 0.28

$0.16M 0.45

$0.11M 0.29

$0.18M 0.49

$4.60M 0.30

$4.58M 0.15

*Indicates Greenroads Programs with multiple phases or segments, each certified separately as a "Project"


TABLE 4 Summary of Project Percent Overshoots and Final Ratings

TABLE 5 Performance Profile of the Average Greenroads Project All Certified Projects Average Certified Project

# Points % of

Total

#

Credits

% of

Total

# Points % of

Total

#

Credits

% of

Total

Environment and Water 285 18% 84 20% 7 18% 3 20%

Access and Equity 322 31% 126 30% 12 32% 5 33%

Construction Activities 110 11% 74 18% 4 11% 3 20%

Materials and Resources 222 21% 60 14% 8 21% 2 13%

Pavement Technologies 145 14% 34 8% 5 13% 1 7%

Custom Credits 62 6% 40 10% 2 5% 1 7%

TOTAL 1046 100% 418 100% 38 100% 15 100%

0% 10% 20% 30% 40% 50%

Overshoot as % of Final Score

17 12 35 Bronze 51 Silver


8 17 45 Silver 59 Gold



18 14 33 Bronze 41 Bronze






28 15 43 Silver 50 Silver

















46%

34%

31%

29%

25%

24%

24%

22%

21%

21%

18%

16%

13%

13%

13%

13%

13%

12%

12%

11%

11%

7%

6%

5%

5%

5%

4%

3%


LIST OF FIGURES

FIGURE 1a Credit rankings by point contribution to cumulative total (top),

1b Running % Contribution to Cumulative Total (bottom)

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

36%

40%

13%

23%

35%

99%

7%

12%

73%

29%

68%

78%

19%

81%

64%

77%

85% 83%

24%

61%

72%

40%

87%

56%

30%

67%

45%

93%

51%

98%

49%

60%

100%98%

100%100%100%100%

45%

53%

EW-6 and Credits to the rightcontribute no additional points

Running % Contribution to Cumulative Total (Credits and Points)

0

20

40

60

80

100

120

140

160

EW-6 and Credits to the right contribute no additional points

Credit Ranking by Total Point Contribution

Legend

Contribution by Credit

Contribution by Points


FIGURE 2 Relative construction and certification timelines for Greenroads projects, sorted by application date and rating level

ID#-600 -400 -200 0 200 400 600 800 1000 1200 1400 1600 1800

Duration

-600 -400 -200 0 200 400 600 800 1000 1200 1400 1600 1800

Duration

7

23

24

25

26

17

11

3

6

10

18

19

20

12

13

14

15

16

21

28

1

8

2

4

5

9

22

27

1,458

1,458

1,458

1,458

1,458

1,126

1,126

1,126

1,230

1,844

1,844

1,844

-189

-116

-116

-116

-116

395

497

497

497

777

777

777

777

563

563

563

563

703567

303

183

777

496

330

734

442

511

-43

-96

-54

98

-8

0

0

0

0

0

0

0

0

0

0

0

0

0

0

0

1,066

1,106

-358

-490

-132

215

758

808

398

183

183

123

213

296

216

880

470

814

434

302

742

242

-28

-78

-57

91

-8

-8

0

0

0

0

0

0

Milestones

Application Date

Certification Date

Construction End

Construction Start


FIGURE 3 Total Project Points Earned by 22 Certified Greenroads Projects

FIGURE 4 Summary of Rating System and Certified Project Scopes

CC

Included

by Credit or

by Points Project or System

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

N PT System Scope

Certified Projects

Average Certified

CR System Scope

Certified Projects

Average Certified

Y PT System Scope

Certified Projects

Average Certified

CR System Scope

Certified Projects

Average Certified

19%

15%

14%

21%

23%

22%

13%

11%

11%

28%

33%

33%

19%

19%

19%

16%16%

16%

14%

22%

20%

21%

24%

33%

36%

22%

22%

21%

9%

7%

17%

14%

13%

19%

21%

21%

12%

11%

11%

25%

31%

32%

18%

18%

18%

8%

6%

5%

20%

10%

13%13%

14%

13%

17%

18%

20%

20%

30%

33%

17%

20%

20% 7%

8%

7%

Greenroads Credit Categories

Environment and Water

Access and Equity

Construction Activities

Materials and Resources

Pavement Technologies

Custom Credits

informing roadway sustainability practices using ...docs.trb.org/prp/16-4844.pdflew, anderson,...

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