Candidate for fully permeable shoulder retrofit validation site
Effect of Pavement Structural Response on Vehicle Fuel Consumption and Emissions: Field Calibration of Models.
Pavements have an influence on the fuel mileage of cars and trucks. For individual cars and
trucks this influence is small (generally less than about 3 percent change in fuel
mileage compared to a “perfect” pavement) relative to the fuel mileage effects of
stop-and-start and “lead foot” driving, the air resistance on a vehicle traveling
over a freeway speed limit, and underinflated tires. But since the pavement effect
applies to every vehicle on the road its cumulative effect is magnified.
The pavement characteristics considered to affect fuel economy are
roughness (bumpiness), texture (the stones sticking out of the surface), and the
structural response (bending under load) of the pavement itself. To date, models
that have had some field calibration only exist for the effects of roughness and texture.
During the summer of 2016, in the second phase of a Caltrans-sponsored study, the
UCPRC investigated the effects of pavement structural response (the bending under load phenomenon),
along with verifying models for roughness and texture.
In Phase 1 of this study, researchers at Michigan State University, the Massachusetts
Institute of Technology, and Oregon State University developed models for the mechanics
of pavement structural response on vehicle fuel consumption. UCPRC researchers then used the
models—along with existing models of roughness and texture—to run simulations of annual fuel
economy in different climate regions, with urban and rural traffic speed (congested, uncongested)
and traffic flow (vehicle types) conditions. (A report on Phase 1 is available
The objectives of Phase 2 of the study are to measure field vehicle fuel consumption on
different pavement types in both winter and summer, and to finalize the development of
calibrated and validated models for vehicle energy consumption due to pavement structural
response that can be used in pavement management and design.
The Phase 2 study began in mid-2015 with the identification and field measurement
response of 21 test sections across northern and central California, including a
range of pavement structure types. The pavement structures are being characterized
for their structural characteristics (material types, thicknesses and stiffnesses), and
surface roughness and texture. A mix of vehicles types is being used to gather fuel
economy measurements: a five-axle, semi-trailer tractor; a 1.5 ton single-axle, dual-tire
diesel truck; an SUV; a gasoline-powered car; and a diesel car. All have been fitted with
new tires that were broken in and then kept in cold storage when they were not in use. On-board
diagnostic systems in each vehicle record air flow, fuel injection, vehicle speed, and fuel
consumption. In addition, temperature and wind conditions are monitored during testing. To ensure
consistency, the same vehicles and drivers are used during testing, and to get statistically
meaningful results a number of runs are made on each section.
The current round of testing is expected to be complete by the end of
September, and the entire project is scheduled to end in early 2017.
Important Note for Caltrans Users: Prior
to scheduling pavement preservation (preventive maintenance or CAPM) or roadway
rehabilitation work on flexible pavement highway sections, the District Materials
Engineer and/or the Project Manager should review
this spreadsheet to
ensure that the proposed project does not include sections active in
the “Quieter Pavement Research” (QPR) testing program. If the proposed
project is within a QPR test section, please
contact Linus Motumah of the
Caltrans Office of Pavement Design before scheduling the work.
To view maps that show where the sections are located, click the following
(or copy-and-paste it into a new browser window for a slightly larger view).
For more information,
contact John Harvey of the UCPRC or