Content uploaded by Lev Khazanovich
Author content
All content in this area was uploaded by Lev Khazanovich on May 26, 2015
Content may be subject to copyright.
BENEFITS OF THE MINNESOTA ROAD RESEARCH PROJECT (MNROAD)
Derek M. Tompkins
Associate Director
Pavement Research Institute
University of Minnesota
Department of Civil Engineering
500 Pillsbury Drive S.E.
Minneapolis, MN 55455
Phone: 612-626-4098
Fax: 612-626-7750
E-mail: tompk019@umn.edu
Lev Khazanovich
Associate Professor
University of Minnesota
Department of Civil Engineering
500 Pillsbury Drive S.E.
Minneapolis, MN 55455
Phone: 612-624-4764
Fax: 612-626-7750
E-mail: khaza001@umn.edu
David M. Johnson
Minnesota Road Research Manager, Retired
Minnesota Department of Transportation
Office of Materials and Road Research
1400 Gervais Avenue
Maplewood, MN 55109
Paper submitted 31 July 2007
in consideration for
Transportation Research Board 87th Annual Meeting, January 13-17, 2008
Words: 6950
Figures: 1
Tables: 1
Photographs: 0
Total Word Count: 7450
Tompkins, Khazanovich, and Johnson
1
BENEFITS OF THE MINNESOTA ROAD RESEARCH PROJECT (MNROAD)
ABSTRACT
The Minnesota Department of Transportation (Mn/DOT) began construction on the Minnesota
Road Research Project (MnROAD) in 1991 and opened the full-scale pavement research facility
to live traffic in 1994. Since the time of its construction, MnROAD, the first major test track
since the AASHO Road Test of the 1950s and 1960s, has learned many lessons in pavement
testing and pavement engineering on behalf of the greater pavement community. Researchers at
the University of Minnesota reviewed these lessons from the first phase of MnROAD (the
facility’s first ten years of operation) for a project titled MnROAD Lessons Learned. The
Lessons Learned project involved over fifty interviews, three hundred published and unpublished
reports, papers, and briefs, and an online survey of pavement professionals. This paper, based on
the Lessons Learned project, presents a sample of the lasting benefits of MnROAD at the local,
state, and national levels. Furthermore, the paper provides extensive references for these benefits
in hopes of increasing awareness of this pavement test facility’s under-publicized contributions
to pavement engineering.
Tompkins, Khazanovich, and Johnson
2
BACKGROUND
In the 1980s, the Minnesota Department of Transportation (Mn/DOT) explored the idea of a
Cold Regions Pavement Research Test Facility (CRPRTF), which led to a task force that
consisted of Mn/DOT engineers and officials, Federal Highway Administration (FHWA) and
Strategic Highway Research Program (SHRP) administrators, representatives of industry, and
consultants from universities. In May 1987, the task force settled upon proposed interstate and
low-volume test section plans for what would be called the Minnesota Road Research Project
(MnROAD) (1). The plans were then unveiled in a number of reports by Dr. Matthew Witczak,
a consultant to the CRPRTF Task Force (2,3).
Concurrent with the development of test section plans was the focus of the task force,
with the specific assistance of Dr. Witczak, the University of Minnesota (UMN), and Mn/DOT
engineers, on research objectives for MnROAD. This early focus on research lead to the
determination of fourteen objectives in research for MnROAD that included the evaluation of
mechanistic and empirical design methods; the verification and further development of frost
prediction methods; and the investigation of base/subbase properties on pavement performance
(4). (More information on these research objectives and the development of MnROAD can be
found in Tompkins and Khazanovich [5].) Having both construction and research plans, various
government and Mn/DOT officials broke ground near Albertville, Minnesota, in 1991 for the
construction of a 3.5-mile interstate roadway and a 2.5-mile low-volume roadway, each roadway
consisting of test sections and over 4500 sensors monitoring pavement response and
environmental data. A schematic of the test sections at MnROAD is provided in Figure 1.
Figure 1. The Low-Volume closed loop and the Mainline test sections at MnROAD (6).
The interstate roadway, or the mainline, is subjected to live traffic redirected from westbound
traffic on US Interstate 94, while the low-volume road is subjected to a controlled 5-axle loading
of 80 kip in one lane and 102 kip in the other. The MnROAD facility opened to traffic in August
1994, and as of December 31, 2003, the mainline flexible test sections received roughly 5 million
Equivalent Single Axle Loads (ESALs) and the mainline rigid sections received approximately
7.8 million ESALs (7).
Tompkins, Khazanovich, and Johnson
3
The following paper will describe some of the products of MnROAD in terms of its
benefits to pavement engineers at the national, state, and local levels. It is hoped that by viewing
a pavement test facility in this manner, the reader is not only able to better understand some of its
products, but is also able to appreciate the far reaching effects of the kind of pavement research
that occurs at a full-scale pavement test facility such as MnROAD.
CONTRIBUTIONS OF MNROAD AT THE NATIONAL LEVEL
MnROAD has been involved in a number of projects with national interest, and some of those
projects are also detailed below.
Pavement Test Track Expertise
The challenge of forging a new path through the thirty years of changes to come about since the
AASHO Road Test meant that MnROAD had many lessons to learn for test tracks and
pavements to come. MnROAD engineers involved in the construction and installation of sensors
at the MnROAD site had the foresight to closely detail their experience in Mn/DOT reports,
exemplified by reports such as Baker et al. (8). This report presented step-by-step installation
procedures for 16 surface sensors installed at MnROAD to collect data on loading in the test
sections. The report also describes testing procedures to verify the operation of the 16 surface
sensors and check for any malfunctions, and the report discusses the survivability of the sensors
and possible sources of sensor failure.
Due to the large amount of sensors installed at MnROAD (over 4500), MnROAD gained
considerable insight into the actual sensor life spans and durability to compare with the claims of
the various manufacturers, and later work at MnROAD dealt with the problem of sensor failure,
which MnROAD experienced on a large scale. One of the more prominent studies into this
problem was conducted by MnROAD engineers and detailed by Burnham (9). This paper came
about due to the failure of the original sensors embedded in MnROAD’s concrete test sections.
To replace these sensors, MnROAD engineers had to determine the orientation of the original
sensors. In doing so, MnROAD engineers discovered that the in-situ position of the sensors
differed greatly from the position intended for them in the original design. Once a feasibility
study was concluded for retrofitting the failed sensors, MnROAD engineers installed new
sensors into holes in the test sections from full-depth coring. These new sensors were then
subjected to loading and monitored to determine if retrofitted sensors provided reliable data on
loading. In this case, the engineers involved felt that the data collected by these new sensors was
at least as accurate as the data collected by the original sensors and thus effective (9).
MnROAD test track expertise was utilized in other major pavement test track facilities,
such as WesTrack, the National Center for Asphalt Technology (NCAT), and the SHRP test road
in Ohio. Officials from these and many other facilities have toured MnROAD and consulted
with MnROAD engineers about the MnROAD facility itself. The willingness of MnROAD to
offer information openly to all interested parties, be the subject test track expertise, data, or
research, is the most significant benefit of its first ten years of operation.
MnROAD Database
Tompkins, Khazanovich, and Johnson
4
The database at MnROAD is one of the main products of MnROAD’s first decade of operation.
While the MnROAD database does not have the sheer volume of test sections and data of the
LTPP database, in other aspects it offers an interested researcher many benefits not available
through LTPP. The construction of all MnROAD cells is closely monitored, and data to
characterize the pavement system across a number of variables is readily available. Many
MnROAD-related reports by Mn/DOT engineers have taken great pains to detail the construction
of individual cells and detail the various properties of each layer of the pavement system (10-16).
Furthermore, an amazing spectrum of dynamic response data characterizing very narrow
intervals in time is available for each section, and the same spectrum is available for data from
regular monitoring of the sections. Table 1 presents a brief summary of the many types of data
regularly collected at MnROAD.
TABLE 1 Types of data collected at MnROAD (17)
Subject Area Data Type Examples of Data Collected at MnROAD
Cell Info Cell Data Design, Construction, Maintenance, Cell Layer/Lift Thickness,
Cell Events, Elevations, GIS Data
Rutting Straight Edge, Automated Laser Profile System (ALPS), Paper
Traces, Pathways, PaveTech, Dipstick
Ride Pathways, PaveTech, Frost Pins, Faulting, Forensics, Friction
Cracking Distress Surveys, Crack Mapping, Cupping
Field
Monitoring
Strength Dynamic Cone Penetrometer (DCP), Falling Weight
Deflectometer (FWD)
Pavement
Biaxial Strain Gage (BS), Concrete Embedment Strain Gage (CD,
CE), Linear Variable Differential Transducer (DT), Horizontal
Clip Gage (HC), Longitudinal Embedment Strain Gage (LE),
Transverse Embedment Strain Gage (TE), Piezo-Accelerometer
(PA), Dynamic Soil Pressure Cell (PG, PK), Steel Strain Gage
(SS), Tiltmeter (TM), Vibrating Wire Strain Gage (VW)
Subsurface
Subsurface Thermocouple (TC), Moisture Block (WM), Dynamic
Pore Water Pressure Cell (DW), Thermistor (XD, XL, XT, XS),
Open Stand Pipe (OS), Static Lateral Pressure Cell (PL), Static
Soil Pressure Cell (PT), Resistivity Probe (RP), Static Pore Water
Pressure Cell (SW), Tipping Bucket (TB), Time Domain
Reflectometer (TD)
Sensor Data
Traffic Mainline and LVR installations of Hydraulic Load cells, Kistler
sensors
Bituminous
Bituminous Dynamic Shear Rheometer, Bending Beam
Rheometer, Direct Tension, Repeated Creep, Zero Shear
Viscosity, Dynamic Modulus, Indirect Tension Test, Fracture
Toughness, Mix Designs, Gradations
Concrete Concrete Air Voids, Compression, Coefficient of Thermal
Expansion, Poisson’s Ratio, Mix Designs
Lab Testing
Unbound Resilient Modulus, Proctor Curves, Field Density, Gradations,
Unsaturated Material Properties
Tompkins, Khazanovich, and Johnson
5
The database also includes non-traditional data such as the forensic trenching data done to
diagnose pavement distresses in asphalt test sections (18-20).
Due to its in-depth response, design, and as-built data for over 40 test sections,
MnROAD’s database has already been incorporated into NCHRP Project 1-37A, and institutions
throughout the world have used MnROAD’s array of constitutive data in pavement design and
research. For example, material property data was used extensively for research reports by the
Finnish National Road Administration (FINRA) in laboratory tests on asphalt mixes and by the
US Army Corps of Engineers Cold Regions Research and Engineering Lab (CRREL) in testing
of frozen soils and modeling of frost depths in subgrades (21-25).
MnROAD Participation in TERRA
In 2004, a task force commissioned to expand the governance of and increasing research
opportunities at MnROAD led to the creation of the Transportation Engineering and Road
Research Alliance (TERRA). TERRA is a pooled-fund consortium whose membership includes
representatives from transportation agencies, private-sector industry, and academic research.
While TERRA was initially founded to support MnROAD, it has since become a more
significant vehicle for national collaborations in pavement research that use MnROAD as a site
for this research. In addition, TERRA also presents MnROAD with an efficient manner of
passing along valuable pavement data and test track expertise to some of TERRA’s members.
As noted by Stehr and Corrigan in TRB’s TR News, the TERRA model for partnerships in road
research has lead to a number of recent partnerships that extend beyond Minnesota. These
partnerships include collaborations between Mn/DOT and/or UMN researchers with the Center
for Transportation Research and Education (CTRE) at Iowa State University, the Michigan DOT,
and the Norwegian Public Roads Administration (26).
Evaluation of and Contributions to Pavement Design Methods
By closely studying MnROAD’s original research objectives, it is clear that MnROAD was
originally designed as a so-called thickness, or structural, experiment. That is to say that
Mn/DOT engineers set out to use the full-scale facility at their disposal to determine how thick a
given pavement needed to be to perform adequately in a cold-region environment. However,
MnROAD engineers quickly observed, with a little help from low-temperature cracking in their
test sections, that the true question of a cold-regions pavement facility is eventually one of
environment. The variety of MnROAD research in pavement design methods over its first ten
years reflects this change in focus.
MnROAD and Pavement Design Calibration and Verification
Much of the early work at MnROAD consisted of characterizing the pavement systems in each
of the test sections. An early partnership between MnROAD and CRREL involved the use of
MnROAD data characterizing its test sections to predict the performance of these test sections
according to the CRREL mechanistic-empirical model for cold regions pavements (27, 28).
Other early work by Berg used MnROAD data to calibrate a frost depth prediction model (29).
Another significant project at MnROAD, by Burnham and Pirkl, involved the application
of data characterizing concrete test sections to the Mn/DOT rigid pavement design guidelines,
the 1993 AASHTO Guide for Design of Pavement Structures (AASHTO-93), and the 1984
Tompkins, Khazanovich, and Johnson
6
Portland Cement Association Thickness Design for Concrete Highway and Street Pavements
(PCA-84). Burnham and Pirkl found that the predicted serviceable life of each test section was
highly variable as the researcher moved between design methods and levels of reliability (30).
The gross inaccuracies of these models and the discrepancies between their predictions as
exposed by Burnham and Pirkl’s study was the first major use of full-scale test track data to
evaluate existing pavement design methods, and this particular study illustrated that the design
methods of the early 1990s were inadequate.
A number of researchers at universities have taken advantage of MnROAD data to
conduct wide-ranging activities in:
• calibrations of finite element structural models;
• validations of mechanistic-empirical design parameters and methods;
• the development of models to predict low-temperature cracking performance of
asphalt pavements;
• evaluations of drainage models for pavement systems; and
• investigations of tire-induced stresses and surface-initiated cracks.
These reports include and are not limited to the work of Alvarez and Thompson, Ariza and
Birgisson, Bao, Forst, Holewinski et al., Marasteanu et al., Mateos and Snyder, Wu et al., and
Zhang et al. (31-40).
Cold Regions Pavement Design Software (MnPave)
MnROAD’s first contribution to a mechanistic-empirical design specific to Mn/DOT was with
the thickness design program ROADENT developed by UMN. Using the WESLEA model for
layered elastic analysis as its basis, university researchers used MnROAD to verify and calibrate
ROADENT for use as a design tool for flexible pavements (41-43). In response to their own
work in seasonal variations in pavements, Mn/DOT and UMN researchers later developed
MnPave, a mechanistic-empirical design software program with its basis in ROADENT but with
many layers of additional sophistication. MnPave was developed using MnROAD performance
data and, to a lesser extent, data from Minnesota highway sections (44, 45).
MnROAD and MEPDG
The NCHRP Project 1-37A design procedure, commonly known as the 2002 Mechanistic-
Empirical Pavement Design Guide (MEPDG), has incorporated a large amount of MnROAD
data and expertise in its on-going calibration. To calibrate MEPDG’s ability to predict rutting in
the lifts of an asphalt pavement, the MEPDG team used forensic trenching data from trench
studies done on MnROAD test sections and described in reports by Isackson et al. and Mulvaney
and Worel (18-20). Furthermore, the thermal cracking model used by MEPDG was calibrated
using MnROAD thermal cracking. PCC performance and temperature data were used to re-
calibrate the rigid models of MEPDG and verify the Enhanced Integrated Climatic Model
(EICM) predictions respectively (46).
Thin and Ultra-Thin Whitetopping
The process of overlaying asphalt pavements with thin concrete layers, known as whitetopping,
is one that has been studied by Mn/DOT since 1993 and at MnROAD since 1997. Since that
Tompkins, Khazanovich, and Johnson
7
time, Mn/DOT engineers at the Office of Materials and Road Research have produced a variety
of reports and presented many papers on the design and construction of whitetopping. These
reports detail MnROAD’s experience with a variety of full-scale thin and ultra-thin whitetopping
designs in both high- and low-volume trafficked MnROAD test sections over a three and a half
year period (47, 48). Mn/DOT researchers have also been involved in a number of whitetopping
experiments on highways and low-volume roads around Minnesota that borrow their design,
construction, and repair techniques from MnROAD test section experience (49-51). MnROAD
has also been in the enviable position of being able to use its wide array of load response sensors
to monitor the performance of these thin concrete slabs in real-time (52). In the course of just
under four years, MnROAD engineers went from having little to no whitetopping experience to
being a driving force behind the design and construction of whitetopping for asphalt pavements
in the United States.
Continuous Compaction Control (Intelligent Compaction)
In the last years of its first ten years of operation, MnROAD engineers were closely involved
with an exciting new tool in pavement construction quality control, continuous compaction
control (more commonly known as “intelligent compaction” or IC). Through demonstrations at
MnROAD and the involvement of MnROAD engineers in a statewide IC Task Force, many
factors related to the use of IC in unbound material compaction have been uncovered through
MnROAD. During the on-site demonstrations, MnROAD engineers confirmed the steps
involved in the IC process and the tools used to complete each step. Engineers also confirmed
the data transfer from compactor to server. Overall, MnROAD engineers found that intelligent
compactors do an excellent job of ensuring uniformity in compaction and acquiring the soil
modulus for the next generation of mechanistic-empirical pavement design (53). Thanks to
MnROAD experience and initiatives, Minnesota has a docket of projects and demonstrations
scheduled that involve IC, and this experience will likely play a large role in the development of
IC in the United States (54).
MNROAD AND THE STATE OF MINNESOTA
The benefits of the Minnesota Road Research facility in the state of Minnesota began from the
moment the facility site was chosen. There have been a number of legislative changes that have
come about thanks to MnROAD’s work in the seasonal variation of pavements. In addition,
Mn/DOT continues to benefit from MnROAD engineers’ experience with new equipment,
construction methods, and pavement assessment techniques, many of which have become
standards or specifications for Mn/DOT. The following sections detail some of the benefits of
MnROAD to the state of Minnesota.
Seasonal Variations in Pavements
One of MnROAD’s most publicized benefits to the state of Minnesota has been in the field of
seasonal variations in pavements. Using data from MnROAD, Ovik et al. were able to conduct a
close analysis of the moduli in various layers of a flexible pavement system. In doing so, the
researchers divided the calendar year into five distinct seasons for the purposes of a mechanistic-
empirical design method specific to Minnesota. This so-called fifth season falls during the early
Tompkins, Khazanovich, and Johnson
8
spring-thaw period, when an excess of moisture is present and the granular base has a minimal
resilient modulus (55).
This innovation in the approach to pavement and environment lead to legislation
concerning spring load restrictions for Minnesota’s roadways (56, 57). The Mn/DOT Office of
Materials and Road Research continued to apply Ovik’s understanding of seasonal variation in
flexible pavement systems to new winter load limits for Minnesota’s roadways (58). Strangely
enough, the work also has indirectly lead to a closer examination of the need for spring-load
restrictions altogether. A recent study found that the reduced maintenance costs due spring-load
restrictions might not outweigh the increased revenue from roadways operating year-round at the
maximum single-axle load (59). Despite the various legislative activity that was instigated by
Ovik et al., the main benefit of this research is its new understanding of cold-regions pavements
and the use of this understanding in developing and calibrating mechanistic-empirical pavement
design methods such as Mn/DOT’s MnPave.
New Techniques for State Pavement Engineers
In addition to serving as a site for research, MnROAD has also served the state of Minnesota as a
testing ground for new pavement technologies. In some cases, this has involved the use of
MnROAD engineers in certifying practitioners in the use of equipment or the use of MnROAD
as a demonstration site (53, 60, 61). Two notable techniques in pavement assessments, the
dynamic cone penetrometer (DCP) and ground penetrating radar (GPR) have been first explored
at MnROAD before seeing greater use by Mn/DOT across the state of Minnesota.
Dynamic Cone Penetrometer
MnROAD personnel have applied the dynamic cone penetrometer (DCP) to test sections since
the initial stages of MnROAD beginning in June 1991. During the construction phase,
MnROAD engineers conducted over 700 DCP tests at the MnROAD facility (62). Since that
time, MnROAD has used the DCP regularly to evaluate newly constructed and rehabilitated
pavements. MnROAD engineers have suggested and made a series of physical modifications to
the device itself, modifications that have now become standard on the DCP as used by Mn/DOT.
Furthermore, to avoid inaccurate results due to operator fatigue, Mn/DOT proposed the
development of an automated DCP (ADCP) (62-64).
MnROAD’s entire efforts with DCP have influenced Mn/DOT and its assessment of
subgrades and pavement systems in the field. Furthermore, MnROAD’s work with DCP
prompted Mn/DOT to incorporate DCP testing in two specifications for pavement assessments:
1) quality control for the backfill compaction of pavement edge drain trenches (Mn/DOT Spec
SP5-128) and 2) quality control of granular base layer compaction (Mn/DOT Spec 2211.3.C4).
Mn/DOT has had the confidence to use DCP testing for a variety of non-specified work that
includes an assessment of base and subgrade conditions under full-depth bituminous cracks and
the foundation strength of footing pads for a building (65, 66).
Ground Penetrating Radar
MnROAD has also benefited Minnesota pavements through the adoption of ground penetrating
radar (GPR) by Mn/DOT. In the earliest work using GPR at MnROAD in 1994, GPR was used
Tompkins, Khazanovich, and Johnson
9
to evaluate the thicknesses of the test sections and compare these values against known design
thicknesses (67). This early test acted as a pilot quality control for MnROAD (to confirm that
sections were constructed to design) and simultaneously as a way for the researcher to compare
the GPR’s assessment against actual thicknesses (determined through coring). In the last five
years, Mn/DOT has purchased and maintains state-of-the-art GPR equipment. MnROAD is used
to calibrate these antennas on a frequent (semi-annual) basis. Metal calibration plates have been
placed at precise locations and depths within several test sections. Since the first use of GPR at
MnROAD, Mn/DOT has expanded both its GPR equipment and user expertise. More
importantly, Mn/DOT has expanded the use of GPR as a useful non-destructive method of
testing and now applies GPR to profile subsurface conditions, to locate underground utilities, and
to assess the condition of bridges (68).
SafeTruck
Some of the more noticeable non-pavement issues investigated at MnROAD have been assistive
or autonomous vehicle guidance systems and the technologies associated with those systems.
These issues arose out of Mn/DOT and MnROAD’s combined need for driver-assist
technologies to ensure the safety of the operator of the truck that provides the load repetitions on
the low-volume road at MnROAD (69). UMN researchers modified a Navistar 9400 truck
tractor (called SafeTruck) that incorporated global positioning system (GPS) response data and a
heads-up display (HUD) prototype that provides a driver with lane boundaries in conditions of
poor visibility. SafeTruck was first successfully demonstrated for the public in April 1997 at the
MnROAD facility (70). Later work used MnROAD to test the driver assistive system (DAS), a
combination of SafeTruck with HUD, differential GPS, and the Virtual Bumper, a series of radar
and laser sensors that detect and respond to potential collisions (71).
MNROAD AND MUNICIPAL AND COUNTY ENGINEERS
In its first decade of operation, MnROAD used its 2.5-mile low-volume road (LVR) for
extensive experiments and continuous data collection on a variety of test sections. Despite the
more highly publicized work on the live-traffic mainline sections, MnROAD has put a great deal
of effort in studying the low-volume roads that make up the majority of Minnesota’s roadways.
Many of these efforts are sponsored by the Minnesota Local Road Research Board (LRRB).
This board consists of municipal and country engineers and exists to promote and fund research
in low-volume roadways. The following benefits to pavement engineers on the local level act as
a brief summary of the MnROAD-LRRB research partnership.
Low-Volume Road Design
The most noteworthy projects to benefit from the wealth of LVR data were those involving
mechanistic-empirical design. LVR data from MnROAD were used by UMN researchers to
verify and calibrate ROADENT, a thickness design program based on WESLEA and developed
by UMN (38-40, 72). The calculated strains from the program were compared to the actual
strains as captured by the many embedded sensors in the test sections. ROADENT was
continuously calibrated in this way so that performance predictions by ROADENT would reflect
the performance observed at MnROAD’s full-scale LVR test sections.
Tompkins, Khazanovich, and Johnson
10
Furthermore, the report recommends that the Soil Factor and R-Value design procedures
for low-volume roads be reconsidered, as ROADENT requires a thicker design than the other
two for an equivalent roadway. This conclusion was significant for local agencies, most of
whom used either the Soil Factor or R-Value design in planning their roadways, and the
foundation of this conclusion was, of course, years worth of MnROAD LVR data. A later
Mn/DOT report by Skok et al. builds upon the earlier work in LVR design by updating the
design for Minnesota using MnPave (73). This work has benefited low-volume roadways at the
city and country level by providing a reliable, consistent design based upon local environmental
data and pavement response data to loading in that particular environment.
Aggregate Road Studies
Mn/DOT and LRRB commissioned a study on MnROAD’s aggregate road test sections shortly
before the removal of those sections, later published in Lukanen (74). This work resulted in a
number of interesting conclusions and recommendations, the foremost of which is on the nature
of full-scale testing itself: the study describes the true measure of the aggregate sections’
performance as their ability to allow the loading truck to pass unimpeded. When the truck could
no longer maintain its 30 mph speed on any single section, all aggregate sections (in addition to
the section causing the problem) would be bladed to avoid safety concerns for the operator of the
truck. Hence, rutting and washboarding were naturally the most closely studied modes of
deterioration. The severity and frequency of these phenomena limited the observations due to
the fact that when one section approached “failure” in terms of the safety concerns for the truck
operator, all sections and ongoing observations were subsequently reset.
Despite this limitation, the study found a strong relationship between washboarding and
the number of truck passes. Due to this relationship, more washboarding occurred in the 80 kip
lane than in the 102 kip lane. Forensic cross-sections of the test cells revealed that the observed
rutting occurred in the aggregate and not the subgrade. It was also found that the use of the chip
seal reduced the likelihood of washboarding, though a comparison between the sections
suggested nothing conclusive as regards chip sealing and rutting. Lukanen’s study concludes by
noting that aggregate gradations are not reliable predictors of performance in an aggregate road.
Another report by Johnson and Baker concludes MnROAD’s experience with its
aggregate test sections discusses the sections in every detail, from construction to load response
to distress observations (75). This report makes a few interesting observations on the rate of
freezing and thawing under aggregate roads. The freeze/thaw under aggregate roads was much
different than the freezing and thawing under HMA sections at MnROAD: the subgrade under
aggregate sections froze approximately 4 to 5 days sooner than the subgrade below the HMA.
Furthermore, the subgrade under the aggregate sections took between 11 and 35 days longer to
thaw than the subgrade under the HMA. This second report was the final report on MnROAD’s
aggregate test sections and is an excellent review of one of the few full-scale, fully instrumented
aggregate roads in the United States.
Road Maintenance and Rehabilitation
Thanks to a number of LRRB initiatives, a great deal of research immediately applicable to
county and city roads was conducted at MnROAD. A number of these projects dealt with the
Tompkins, Khazanovich, and Johnson
11
maintenance and rehabilitation practices of local engineers, and a few of these projects are
discussed below.
Edge-Joint Sealing
In an experiment to determine the efficacy of sealing the longitudinal shoulder edge-joint, Olson
and Roberson examined two similar concrete test sections at MnROAD with bituminous
shoulders and edge drains (76). One of these sections acted as a control and did not have its
longitudinal edge joint (the joint between the shoulder and the pavement) sealed. The second
section was, therefore, the test. Before sealing the test section, the two sections were monitored
and found to have no significant differences in the volume of water drained. After sealing and
close monitoring for two years, the total volume of water entering the pavement system for a rain
event was reduced by as much as 85% through the use of an edge seal. The authors recommend
sealing of the longitudinal shoulder edge-joint as a component of any rigorous preventative
maintenance program.
Oil-Gravel Roads
MnROAD has been involved with a number of experimental techniques and materials, and its
experience with emulsified oil gravel is certainly unique to test tracks. This experience came
about through a long-lasting partnership with FINRA. The oil gravel, which consists of a softer
binder than a typical hot mix asphalt (HMA) mix, typically exhibits a long life and low amount
of cracking in Finland. Given its experience with low temperature cracking, MnROAD officials
implemented oil-gravel on three sections in the low-volume loop (77). One of the sections
showed distresses shortly after construction, but a forensic trench study of the section suggested
that the distress was due to the strength of the base material and not a fault of the oil-gravel
surface (19). This section was replaced, but two of the original three oil-gravel sections remain
at MnROAD. These sections have performed very well, and unlike their HMA counterparts,
have resisted thermal cracking entirely (78, 79). MnROAD’s experience in oil-gravel roads
combined with the remainder of Mn/DOT’s experience with oil gravel throughout the state has
helped to educate municipal and city engineers about oil gravel, a new pavement technology for
road rehabilitation that would have gone unexplored had it not been for MnROAD’s partnership
with FINRA.
CONCLUSIONS
From the outset, Mn/DOT intended MnROAD not only as a site for cold regions research, but
more importantly as a site for collaboration on the state, local, and federal levels in the study of
pavement and pavement technologies. This desire for collaboration was first realized in planning
and later the construction of MnROAD, which was funded by Mn/DOT, FHWA, and the
Minnesota Local Road Research Board, a consortium of members interested in research of
municipal and county roads, and the early spirit of partnership in full-scale pavement testing has
continued to this day through MnROAD’s participation in TERRA and various pooled fund
studies.
This paper presented a small selection of the accomplishments of MnROAD as they
benefit local, state, and national practitioners and researchers of pavements. While many of
Tompkins, Khazanovich, and Johnson
12
these benefits are tangible and can be found in new technologies, specifications, and so on, many
of the benefits are as yet unrealized. One of the problems of the MnROAD project is that in spite
of its significant pavement data, expertise, and large library of useful reports, MnROAD has
either insufficiently publicized its findings on a national level or has been simply overlooked by
other researchers outside of Minnesota. It is hoped that this paper will encourage readers
interested in accelerated pavement testing or other pavement-related topics to further investigate
MnROAD and incorporate the underutilized resource of MnROAD data, test track expertise, and
pavement analysis into their own work.
ACKNOWLEDGEMENTS
The authors acknowledge the assistance of Ben Worel, MnROAD Operations Engineer, in
multiple phases of the Lessons Learned project. Furthermore, the authors thank Tim Clyne,
Shongtao Dai, Bernard Izevbekhai, Maureen Jensen, Greg Johnson, Marc Loken, Roger Olson,
John Pantelis, and John Siekmeier of Mn/DOT’s Office of Materials and Road Research and all
survey respondents and interview subjects for their contributions to the Lessons Learned project.
REFERENCES
1. M.W. Witczak and R. O. Wolters. Background and Conceptual Plan: Mn/DOT Cold
Regions Pavement Research Test Facility (CRPRTF). Internal report available upon
request. Minnesota Department of Transportation (Mn/DOT), 1989.
2. DAMA, Inc. Pavement Test Section Plan: Low Volume Road Site – Access Road.
Mn/DOT I-94 Cold Resions Pavement Research Test Facility (CRPRTF). Internal report
available upon request. Mn/DOT, 1988.
3. DAMA, Inc. Pavement Test Section Plan: I-94 Main Experiment – 5 and 10 Year Design.
Mn/DOT I-94 Cold Resions Pavement Research Test Facility (CRPRTF). Internal report
available upon request. Mn/DOT, 1988.
4. Newcomb, D. E., D. M. Johnson, H. B. Baker, and S. M. Lund. Minnesota Road
Research Project: Work Plan for Research Objectives. Report MN-RC-1990-03.
Mn/DOT, 1990.
5. Tompkins, D. and L. Khazanovich. MnROAD Lessons Learned. Report MN-RC-2007-
16. Mn/DOT, 2007.
6. MnROAD Mainline and Low Volume Test Road Main Page. Minnesota Road Research
Project, Mn/DOT.
http://www.mrr.dot.state.mn.us/research/cell_info/trackml_lv.asp. Accessed July 31,
2006.
7. Worel, B. and L. Eaton. MnROAD Phase-1 Summary and Phase-2 Future Vision.
Presented at 2nd International Conference on Accelerated Pavement Testing,
Minneapolis, MN, 2004.
8. Baker, H. B., M. R. Buth, D. A. Van Deusen. Minnesota Road Research Project Load
Response Instrumentation Installation and Testing Procedures. Report MN-RC-1994-01.
Mn/DOT, 1994.
9. Burnham, T. R. Concrete Embedment Strain Sensors at the MnROAD Project: As-Built
Orientation and Retrofit. Presented at 1st International Conference on Accelerated
Pavement Testing, Reno, Nevada, 1999.
Tompkins, Khazanovich, and Johnson
13
10. Burnham, T. and D. Johnson. In Situ Foundation Characterization Using the Dynamic
Cone Penetrometer. Report MN-RC-1993-05. Mn/DOT, 1993.
11. Newcomb, D. E., Van Duesen, D. A. and T. R. Burnham. Characterization of Subgrade
Soils and Granular Base Materials at the Minnesota Road Research Project. Report MN-
RC-1994-19. Mn/DOT, 1994.
12. Burnham, T. R. Minnesota Road Research Project Subgrade and Base Material
Sampling and Testing Guide. Report MN-RC-1995-03. Mn/DOT, 1995.
13. Newcomb, D. E., Chadbourn, B. A., Van Duesen, D. A. and T. R. Burnham. Initial
Characterization of Subgrade Soils and Granular Base Materials at the Minnesota Road
Research Project. Report MN-RC-1996-19. Mn/DOT, 1996.
14. Stroup-Gardiner, M. and D. E. Newcomb. Investigation of Hot Mix Asphalt Mixtures at
MnROAD. Report MN-RC-1997-06. Mn/DOT, 1997.
15. Vandenbossche, J. M. and D. L. Rettner. The Construction of US-169 and I-94
Experimental Thin and Ultra-Thin Whitetopping Sections in Minnesota. Report MN-RC-
2001-07. Mn/DOT, 2001.
16. Burnham, T. R. Construction Report for MnROAD PCC Test Cells 32, 52, and 53. Report
MN-RC-2002-04. Mn/DOT, 2002.
17. Worel, B. Guide to the MnROAD Database. Report in Process for Mn/DOT Library.
Mn/DOT, 2006.
18. Isackson, C., S. Dai, and D. Boerner. Minnesota Road Research Project Forensic
Investigation 199701. Report MN-RC-1999-33. Mn/DOT, 1999.
19. Mulvaney, R. and B. Worel. MnROAD Cell 26 Forensic Investigation. Commercially
Unpublished Report to Office of Materials and Road Research. Mn/DOT, 2001.
20. Mulvaney, R. and B. Worel. MnROAD Mainline Rutting Forensic Investigation.
Commercially Unpublished Report to the Office of Materials and Road Research.
Mn/DOT, 2002.
21. Berg, R. L., S. R. Bigl, J. Stark, and G. Durell. Resilient Modulus Testing of Materials
from MnROAD, Phase 1. Report MN-RC-1996-21. Mn/DOT, 1996.
22. Bigl, S. R and R. L. Berg. Testing of Materials from the Minnesota Cold Regions
Pavement Research Test Facility. Report MN-RC-1996-24. Mn/DOT, 1996.
23. Huhtala, M., H. Spoof, L. Saarinen, and P. Halonen. Asphalt Mixture Laboratory Tests.
Report MN-RC-1997-20. Mn/DOT, 1997.
24. Huhtala, M., H. Spoof, L. Saarinen, and P. Halonen. Minnesota Road Research Project
(MnROAD) - Asphalt Mixture Laboratory Tests. Report nr. 395. Technical Research
Centre of Finland, 1997.
25. Saarenketo, T. Tube Suction Test – Results of Round Robin Tests on Unbound
Aggregates. Finra Report 19/2000. Finnish National Road Administration, 2000.
26. Stehr, R. and F. Corrigan. The Transportation Engineering and Road Research Alliance.
TR News, No. 249, March-April 2007, pp. 3-7.
27. Bigl, S. R and R. L. Berg. Modeling of MnROAD Test Sections with the CRREL
Mechanistic Pavement Design Procedure. Report MN-RC-1996-22. Mn/DOT, 1996.
28. Bigl, S. R and R. L. Berg. Material Testing and Initial Pavement Design Modeling:
Minnesota Road Research Project. Report MN-RC-1996-23. Mn/DOT, 1996.
29. Burnham, T. R. and W. M. Pirkl. Application of Empirical and Mechanistic-Empirical
Pavement Design Procedures to MnROAD Concrete Pavement Test Sections. Report
MN-RC-1997-14. Mn/DOT, 1997.
Tompkins, Khazanovich, and Johnson
14
30. Forst, J. Calibration of Rigid Pavement Structural Model Using MnROAD Field Data.
M.S. Thesis. University of Minnesota, Minneapolis, 1998.
31. Alvarez, C. and M. R. Thompson. Mechanistic-Empirical Evaluation of the MnROAD
Mainline Flexible Pavement Sections. Report FHWA-IL-UI-263. Illinois Department of
Transportation, 1998.
32. Bao, W. Calibration of Flexible Pavement Structural Model Using MnROAD Field Data.
M.S. Thesis. University of Minnesota, Minneapolis, 2000.
33. Mateos, A. M. Load Equivalency Factors from the Structural Response of Flexible
Pavements. M.S. Thesis. University of Minnesota, Minneapolis, 2000.
34. Mateos, A. and M. B. Snyder. Validation of Flexible Pavement Structural Response
Models with Data from the Minnesota Road Research Project. In Transportation
Research Record: Journal of the Transportation Research Board, No. 1806, TRB,
National Research Council, Washington, D.C., 2002, pp. 19–29.
35. Zhang, Z., H. K. Stolarski, and D. E. Newcomb. Development and Simulation Software
for Modelling Pavement Response at MnROAD. Report MN-RC-1994-31. Mn/DOT,
1994.
36. Berg, R. L. Calculating Maximum Frost Depths at MnROAD: Winters 1993-94, 1994-95,
and 1995-96. Report MN-RC-1997-21. Mn/DOT, 1997.
37. Ariza, P. and B. Birgisson. Evaluation of Water Flow through Pavement Systems. Report
MN-RC-2002-30. Mn/DOT, 2002.
38. Wu, H., J. Mahoney, G. Turkiyyah, L. M. Pierce, J. Uhlmeyer, and R. Mulvaney. Non-
Uniform Tire Pressure Effects on Surface Initiated Cracks with EverFlex: A Three-
Dimensional FEA Tool for Flexible Pavements. Presented at 9th International Conference
on Asphalt Pavements, International Society for Asphalt Pavements, Copenhagen, 2002.
39. Holewinski, J. M., S. Soon, A. Drescher, and H. Stolarski. Investigation of Factors
Related to Surface-Initiated Cracks in Flexible Pavements. Report MN-RC-2003-07.
Mn/DOT, 2003.
40. Marasteanu, M. O., X. Li, T. R. Clyne, V. R. Voller, D. H. Timm, and D. E. Newcomb.
Low Temperature Cracking of Asphalt Concrete Pavements. Report MN-RC-2004-23.
Mn/DOT, 2004.
41. Chadbourn, B.A., D. E. Newcomb and D. H. Timm, “Measured and Theoretical
Comparisons of Traffic Loads and Pavement Response Distributions,” Proc. 8th Intl.
Conf. on Asphalt Pavements, University of Washington, Seattle, 1997.
42. Timm, D. H., B. Birgisson, and D. E. Newcomb. Mechanistic-Empirical Flexible
Pavement Thickness Design: The Minnesota Method. Report MN-RC-1999-10. Mn/DOT,
1999.
43. Timm, D. H., B. Birgisson, D. E. Newcomb, and T. V. Galambos. Incorporation of
Reliability into the Minnesota Mechanistic-Empirical Pavement Design Method. Report
MN-RC-1999-35. Mn/DOT, 1999.
44. Chadbourn, B., S. Dai, P. Davich, J. Siekmeier, and D. Van Deusen. Mn/DOT Flexible
Pavement Design - MnPave Beta Version 5.1. Commercially Unpublished Report for the
Office of Materials and Road Research. Mn/DOT, 2002.
45. Chadbourn, B. MnPave Homepage. Mn/DOT, Office of Materials and Road Research,
Maplewood, Minnesota.
http://www.mrr.dot.state.mn.us/research/mnpave/mnpave.asp
Tompkins, Khazanovich, and Johnson
15
46. Darter, M. NCHRP Project 1-40D(02), Technical Assistance to NCHRP and NCHRP
Project 1-40A: Versions 0.9 and 1.0 of the M-E Pavement Design Software. Project in
Process, TRB, National Research Council, Washington, D. C., 2006.
http://www4.trb.org/trb/crp.nsf/All+Projects/NCHRP+1-40D(02)
47. Vandenbossche, J. and A. J. Fagerness. Performance, Analysis, and Repair of Ultra-Thin
and Thin Whitetopping at Minnesota Road Research Facility. In Transportation Research
Record: Journal of the Transportation Research Board, No. 1809, TRB, National
Research Council, Washington, D.C., 2002, pp. 191–198.
48. Vandenbossche, J. M. and D. L. Rettner. One-Year Performance Summary of
Whitetopping Test Sections at the MnROAD Test Facility. Presented at the 1st
International Conference on Accelerated Pavement Testing, Reno, Nevada, 1999.
49. Vandenbossche, J. M. and D. L. Rettner. The Construction of US-169 and I-94
Experimental Thin and Ultra-Thin Whitetopping Sections in Minnesota. Report MN-RC-
2001-07. Mn/DOT, 2001.
50. Vandenbossche, J. The Construction and Performance of Ultra-Thin Whitetopping
Intersections on US-169. Report MN-RC-2004-19. Mn/DOT, 2004.
51. Burnham, T. and D. Rettner. Whitetopping and Hot-Mix Asphalt Overlay Treatments for
Flexible Pavement: Minnesota Case History. In Transportation Research Record:
Journal of the Transportation Research Board, No. 1823, TRB, National Research
Council, Washington, D.C., 2003, pp. 3-10.
52. Vandenbossche, J. M. The Measured Response of Ultra-Thin and Thin Whitetopping to
Environmental Loads. Presented at 7th International Conference on Concrete Pavements,
Orlando, Florida, 2001.
53. Petersen, D. L. Continuous Compaction Control MnROAD Demonstration. Report MN-
RC-2005-07. Mn/DOT, 2005.
54. Siekmeier, J., L. Petersen, C. Nelson, and R. Peterson. Intelligent Soil Compaction:
Technology, Results, and a Roadmap toward Widespread Use. In TRB 85th Annual
Meeting Compendium of Papers. CD-ROM. Report 06-2914. Transportation Research
Board, Washington, D.C., 2006.
55. Ovik, J. M., B. Birgisson, and D. E. Newcomb. Characterizing Seasonal Variations in
Pavement Material Properties for Use in a Mechanistic-Empirical Design Procedure.
Report MN-RC-2000-35. Mn/DOT, 2000.
56. Ovik, J. M., D. A. Van Deusen, and J. A. Siekmeier. Improved Spring Load Restriction
Guidelines Using Mechanistic Analysis. Report MN-RC-2000-18. Mn/DOT, 2000.
57. Minnesota Department of Transportation. 2000 Spring Load Restrictions Task Force
Legislative Report. Commercially Unpublished Report. Mn/DOT, 2001.
58. Ovik, J. M. and J. A. Siekmeier. Investigation of the Impact of Increased Winter Load
Limits. Report MN-RC-2004-25. Mn/DOT, 2004.
59. Smalkoski, B., N. Li, and D. Levinson. Economic Effects of Lifting the Spring Load
Restriction Policy in Minnesota. In TRB 85th Annual Meeting Compendium of Papers.
CD-ROM. Report 06-1495. Transportation Research Board, Washington, D.C., 2006.
60. Janisch, D. W. and C. M. Turgeon. Sawing and Sealing Joints in Bituminous Pavements
to Control Cracking. Report MN-RC-1996-27. Mn/DOT, 1996.
61. Thomas, J. Mn/DOT Pavement Smoothness Measuring Device Certification Program.
Commercially Unpublished Report. Mn/DOT, 2005.
Tompkins, Khazanovich, and Johnson
16
62. Burnham, T. and D. Johnson. In Situ Foundation Characterization Using the Dynamic
Cone Penetrometer. Report MN-RC-1993-05. Mn/DOT, 1993.
63. Newcomb, D. E., Van Duesen, D. A. and T. R. Burnham. Characterization of Subgrade
Soils and Granular Base Materials at the Minnesota Road Research Project. Report MN-
RC-1994-19. Mn/DOT, 1994.
64. Newcomb, D. E., Chadbourn, B. A., Van Duesen, D. A. and T. R. Burnham. Initial
Characterization of Subgrade Soils and Granular Base Materials at the Minnesota Road
Research Project. Report MN-RC-1996-19. Mn/DOT, 1995.
65. Burnham, T. R. Application of Dynamic Cone Penetrometer to Minnesota Department of
Transportation Pavement Assessment Procedures. Report MN-RC-1997-19. Mn/DOT,
1997.
66. Siekmeier, J. A., D. Young, and D. Beberg. Comparison of the Dynamic Cone
Penetrometer with Other Tests During Subgrade and Granular Base Characterization in
Minnesota. Nondestructive Testing of Pavements and Backcalculation of Moduli: Third
Volume, ASTM STP 1375, S. D. Tayabji and E. O. Lukanen, Eds., American Society for
Testing and Materials, West Conshohocken, PA, 1998.
67. Maser, K. Ground Penetrating Radar Survey of Pavement Thickness on MnROAD
Sections. Report MN-RC-1995-06. Mn/DOT, 1995.
68. Loken, M. Current State of the Art and Practice of Using GPR for Minnesota Roadway
Applications. Commercially Unpublished Final Report for Investigation Number 771.
Minnesota Local Road Research Board, 2005.
69. Shankwitz, C. and M. Donath. Autonomous Vehicle Guidance Evaluation. Report MN-
RC-1995-12. Mn/DOT, 1995.
70. Alexander, L., S. Bajikar, H. Lim, V. Morellas, T. Morris, and M. Donath. SafeTruck –
Sensing and Control to Enhance Vehicle Safety. Report MN-RC-1998-29. Mn/DOT,
1998.
71. Rakuskas, M., N. Ward, C. Shankwitz, A. Gorejestani, and M. Donath. System
Performance and Human Factors Evaluation of the Driver Assistive System (DAS):
Supplemental Track Test Evaluation. Report MN-RC-2004-12. Mn/DOT, 2004.
72. Skok, E. L., D. E. Newcomb, and D. H. Timm. Minnesota Low Volume Road Design
1998. Report MN-RC-1999-34. Mn/DOT, 1999.
73. Skok, E. L., D. H. Timm, M. L. Brown, and T. R. Clyne. Best Practices for the Design
and Construction of Low-Volume Roads. Report MN-RC-2002-17REV. Mn/DOT, 2002.
74. Lukanen, E. O. An Evaluation of Aggregate and Chip Seal Surfaced Roads at MnROAD.
Report MN-RC-1998-24. Mn/DOT, 1997.
75. Johnson, G. D. and D. Baker. Evaluation of Aggregate Sections at MnROAD. Report
MN-RC-2000-29. Mn/DOT, 2000.
76. Olson, R. and R. Roberson. Edge-Joint Sealing as a Preventative Maintenance Practice.
Report MN-RC-2003-26. Mn/DOT, 2003.
77. Wood, T. J. Low Volume Road Construction with Oil-Gravel. Commercially Unpublished
Report to Office of Materials and Road Research. Mn/DOT, 1999.
78. Johnson, G. Minnesota’s Experience with Thin Bituminous Treatments for Low-Volume
Roads. In Transportation Research Record: Journal of the Transportation Research
Board, No. 1819, TRB, National Research Council, Washington, D.C., 2003, pp. 333–
337.
Tompkins, Khazanovich, and Johnson
17
79. Clyne, T. R., E. N. Johnson, and T. J. Wood. Performance of Oil Gravel Test Sections in
Minnesota. Commercially Unpublished Report to Office of Materials and Road Research.
Mn/DOT, 2005.
