Concrete inFocus - Spring 2014 - (Page oc5)
infocus online connections
and Fuel Consumption
MIT Concrete Sustainability Hub Executive Summary
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.
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.
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
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 cshub.mit.edu.
* 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
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
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