Quantify and Incorporate Environmental Benefits into Life Cycle Costing Models for Common Roadway Construction Practices

Focus Area

Construction and Maintenance Practices


Environmental Process, Natural Resources






2-3 years

Research Idea Scope

Common roadway construction practices impact our environment. Impacts to streams and rivers have been monitored and are considered in the design and construction process. Efforts have been made to reduce other impacts of roadway construction such as dust, noise and emissions. However, the benefits of reducing each of these environmental impacts have not been measured. There is no readily available means of evaluating roadway construction practices that are more environmentally sound than conventional construction practices. Development of a baseline for environmental impacts is required in order to measure and quantify the benefits of impact reduction. 
Sustainable pavement practices include reusing and recycling materials to construct roads that remain safe and durable while reducing emissions, energy use, and waste. With quantifiable environmental benefits, new technologies that support sustainable pavement practices can be measured. The measured benefits provide the most value when incorporated into a decision support tool for the selection of new roadway construction and rehabilitation alternatives.
The decision support tool is life cycle costing. Many pavement life cycle cost models focus on the economic aspect of the alternatives, but fail to consider the social and environmental impacts. There is a need to develop a more comprehensive life cycle costing model to evaluate the relative costs and environmental benefits of the material and processes used.   In order to effectively guide decisions on pavement alternative selections to improve environmental performance, it is essential to develop research on quantifying and incorporating the environmental benefits associated with road building into the current life cycle costing models. 
Identify key environmental impacts of common roadway construction operations and quantify each impact to establish a baseline. Measure the influence that reduced levels of impact have in relation to proximity from the roadway.
Develop a mechanism to quantify and incorporate environmental benefits associated with common roadway construction practices into agency life cycle cost models.
Related Work
There is limited data and research material available related to quantifying environmental impacts. The context of the proposed study is to develop a common mechanism that can be applied by all agencies.  Lewis, Rasdorf, Frey, Pang and Kim discussed the impact of diesel engines on mobile source air pollution and issues associated with measuring this impacts (ASCE, 2009). Surahyo and El-Diraby developed a scheme for environmental and social costs of highway projects that included three case studies (ASCE, 2009). Huang, Bird and Bell considered emissions from maintenance equipment in comparison to disrupted traffic using life cycle cost comparison (2009). Life cycle cost assessment of Warm Mix Asphalt was presented by Hassan (TRB, 2009). He noted a 24% reduction in air pollution. Caltrans is currently measuring emissions from heavy duty construction equipment. Each of these studies contributes to the overall issue, but does not address the spectrum of environmental impacts.
The first step is to establish a quantitative baseline of key environmental impacts. The second step is to develop a common system to measure the environmental benefits based on various environmentally friendly processes and techniques. The final step is to utilize these quantified environmental benefits and incorporate them into a life cycle cost model.
Currently there are a few “green rating” systems being developed to quantify the environmental benefits of transportation engineering:

Green Roads developed by University of Washington in partnership with LEEDTM (development of the second generation)
NYSDOT GreenLites Project Design Certification Program (completed)
Alberta / Stantec Green Guide for Roads (under development)
Transportation Association of Canada (TAC) Green Guide for Road Task Force (under development)
Ontario – MTO Green Pavement Rating System (under development)
These “green rating” systems all follow the same principle and objective, which is to quantify the environmental impacts of road construction projects, but each system is different. For example, the Ontario MTO Green Pavement Rating System focuses on the pavement alternatives during design and construction, whereas Green Roads developed by University of Washington focuses on design and construction, as well as various other aspects of road building such as mobility and safety.
Most current research studies emphasize quantification of environmental benefits, but they have not taken a step forward to incorporate these results into a decision model. Ontario’s MTO Green Pavement Rating System is unique in that is proposing to quantify and incorporate the environmental benefits into life cycle cost models by applying a discounted cost adjustment. This concept is currently under development, but the framework is readily available to serve as a backbone of this study.
There is a national sense of urgency regarding both Global Warming and Congestion Mitigation, but the road construction industry lacks a benchmark and a methodology to address these two key social issues. Without a methodology and a baseline, environmental impacts cannot be measured and compared with improvements to equipment and processes used in common roadway construction practices.
 Quantifying and incorporating environmental benefits into a life cycle cost model is an overarching topic where the demand on our practitioners is significant. Sustainability in transportation infrastructure has a huge impact to our society, every effort to improve the effectiveness of environmental performance is essential. Consequently, the Climate Change TF committee has assessed and selected this topic for a research need statement submission.

Urgency and Payoff

The outcome of the research is a baseline measurement of environmental impacts and a mechanism to quantify the environmental benefits that can be incorporated into life cycle costing models for roadway construction activities. This built-in environmental component in the life cycle cost model would be transferable and could be implemented by any agency that carriers out life cycle costing.
Sustainability considers social, economic and environmental (SEE) impacts. The research will provide a decision support tool to minimize SEE impacts of a project.
The research will be successful if key environmental impacts are identified, best practices for measuring these impacts are described, and data is collected from a variety of locations to provide baseline data.
 The research will enhance the existing roadway life cycle costing models by incorporating an environmental component, which leads to an alternative decision based on SEE impacts. The environmental component is assessed through quantifying sustainability, which includes: context sensitive design, materials and resources, energy and atmosphere, etc. The quantification of environmental benefits will also serve as a mechanism for designers to be aware of the opportunities to incorporate sustainability into their projects.

Suggested By

RNS. Sponsoring Committee: A0020T, Special Task Force on Climate Change and Energy Source Info: Special Task Force on Climate Change and Energy January 2010 Workshop