Concrete inFocus - Spring 2014 - (Page oc5)

infocus online connections Pavement Roughness and Fuel Consumption MIT Concrete Sustainability Hub Executive Summary R ough roads are about more than just an uncomfortable ride. The roughness of a road is one indicator of how soon it will need maintenance or reconstruction, which is tied to federal and state budget allocations. Furthermore, rougher roads can decrease the efficiency of a vehicle, increasing fuel use and greenhouse gas emissions. While roughness is a common measurement around the world, its impact on fuel efficiency is less understood. Approach The roughness of U.S. roads is regularly measured by state and federal officials. Measurements are compared using a standard scale, known as the International Roughness Index (IRI), providing one metric in the set of criteria officials use to prioritize failing roads for maintenance and distribute budget funding appropriately. The consistency and regularity of roughness measurements has led to a robust database: the Federal Highway Administration (FHWA) Long Term Performance program (LTPP). The MIT Concrete Sustainability Hub (CSHub) leveraged LTPP data to understand the impact of roughness of fuel efficiency. To do so, roughness data was first linked to pavement materials and structure. Analyzing how roughness levels evolve on a given road segment over time sheds light on how different designs perform over time in terms of roughness. Secondly, data on traffic patterns can be connected to LTPP data, revealing the impact of traffic type and volume on pavement roughness over time. Finally, these analyses were combined and linked to the World Bank's commonly used fuel consumption model to estimate roughness-related fuel use over the lifetime of a road. Findings The LTTP data show that all common pavement types deteriorate at roughly the Cumulative roughness-related fuel consumption for roughness and deflection for traffic traveling over a sample road over the course of 14 years. same rate, with the continuously reinforced concrete pavement displaying slightly lower deterioration rate. Adding the additional complexity of traffic volume, more significant differences emerge within the pavement types. The CSHub found that roughness alone contributed to the consumption of an additional 30,000 gallons per mile for the representative road section over the study period, as shown in the figure. This equates to the cumulative release of 300 tons of CO2 per mile of pavement. While this information points to the importance of maintaining roads to reduce roughness, additional work needs to be done to understand how representative this pavement section is of the U.S. roadway system. The impact of roughness, coupled with the pavement deterioration rate and road design, can help stakeholders understand ways to leverage road design and maintenance schemes in order to minimize fuel use and greenhouse gas emissions and maximize the use of limited road construction and maintenance funding. ■ The full report on which this executive summary is based is available at KEY POINTS * Roughness is a key metric used to monitor and maintain our nation's roadways. The Concrete Sustainability Hub developed a method to use existing roughness and traffic data to estimate roughness-related fuel consumption in relation to pavement material and structure. * A sample case study shows a significant impact on fuel consumption due to roughness, with an increase in consumption of 30,000 gallons of fuel per mile over a 14-year test period. concrete INFOCUS ı OC5

Table of Contents for the Digital Edition of Concrete inFocus - Spring 2014

Emergence of Compressed Natural Gas
MMC Materials Converts to Compressed Natural Gas
Fuel Saving Tips from Coast to Coast
Responsible Sourcing for Concrete
NRMCA Services and Tools
Index of Advertisers
Corporate Suite
Concrete Mixer Trucks and the Environment: Get the Connection?
Pavement Roughness and Fuel Consumption
CEMEX ‘Job-Safe’ Program Wins NRMCA 2013 Innovation in Training Award

Concrete inFocus - Spring 2014