Combatting Pavement Roughness with ROSAN
Smoother pavements mean more satisfied customers. As noted in the
recent Federal Highway Administration (FHWA) survey, Moving Ahead:
The American Public Speaks on Roadways and Transportation in Communities,
improvements in pavement conditions are one of the factors that may
result in the greatest rise in traveler satisfaction. To better measure
the smoothness of roads after paving, while allowing traffic to flow
unimpeded, FHWA's Federal Lands Highway offices are using a new device
known as ROSAN (ROad Surface ANalyzer).
Developed by FHWA's Turner-Fairbank Highway Research Center in partnership
with the firm MGPS, ROSAN is a noncontact portable profiler. The laser-based
profiler is capable of measuring longitudinal texture and pavement
profiles at highway speeds. "Being able to do all the pavement
measurements at highway speeds is one of the greatest benefits of
using ROSAN, as you do not have to stop traffic," says Laurin
Lineman of FHWA. By eliminating the need for lane closures and other
traffic control measures, the use of ROSAN can also reduce costs.
The ROSAN system consists of a laser, optical interface, accelerometer,
pulser, and computer. With the exception of the computer, the entire
unit fits in one case and is transportable. The unit can be mounted
on vehicles that have a step bumper, as well as any vehicle to which
mounting brackets can be permanently installed. The device's user-friendly
interface is Windows-based and can be easily operated. ROSAN is capable
of sample intervals ranging from 0.25 mm (.00975 in) to 25 mm (.975
in) and sampling speeds ranging from 24 km/h (15 mi/h) to 104 km/h
(65 mi/h), depending on the sampling interval.
FHWA's Federal Lands offices have been evaluating the smoothness and
roughness measuring capabilities of ROSAN since May 2000. In August
2000, Federal Lands gave ROSAN a tryout at the Mn/ROAD pavement test
facility in Minnesota. More than 216 longitudinal traces were taken
to evaluate ROSAN's variability depending on the operator, data acquisition
speed, and vehicle type. The test results proved to be consistent,
despite the changes in operator, speed, and vehicle type. In August
of 2001, Eastern Federal Lands staff and Virginia Department of Transportation
(DOT) personnel tested ROSAN at Virginia's Smart Road in Blacksburg.
This 2.7-km (1.7-mi) two-lane road is a state-of-the-art test site
for conducting pavement research and evaluating new transportation
technologies. Field spot checks showed that texture measurements done
with ROSAN correlated well with the known texture values that had
been obtained at the site using the traditional sand patch method
and a CT meter (a stationary laser-based method for measuring texture).
Also in August, the Central Federal Lands Highway Division demonstrated
ROSAN's texture measurement capability to Colorado DOT on Interstate
225 in Denver. The Eastern Federal Lands office, meanwhile, demonstrated
ROSAN to representatives from the Maryland State Highway Administration
and Virginia DOT. Measurements for texture smoothness and roughness
were performed. Of particular interest to the observers was ROSAN's
capability to measure and identify aggregate segregation. In a recent
report prepared by the National Center for Asphalt Technology and
issued by the National Cooperative Highway Research Program, Report
441: Segregation in Hot-Mix Asphalt Pavements, ROSAN was identified
as one of only two technologies that could be used to identify segregation.
Federal Lands is currently evaluating ROSAN's texture measurement
module to obtain the necessary data to develop a construction quality
control specification for aggregate segregation.
FHWA's three Federal Lands Offices are also currently using ROSAN
to collect IRI data on paving projects. Data is being collected on
both the original surface before paving and on the final surface.
This data will be used to write a roughness improvement specification.
For more information on ROSAN, contact Laurin Lineman at the Eastern
Federal Lands office, 703-404-6268 (email: laurin.lineman@fhwa.dot.gov).
For more information on other lightweight pavement profilers and FHWA's
overall pavement smoothness initiative, see November 1999 Focus.
 |
| ROSAN
is a laser-based profiler capable of pavement measurements at
highway speeds. |
Other articles in this issue:
From Arizona to Alaska: Maintaining
access and mobility on federal lands highways
Cold in-place recycling a success
in the badlands
New data collection tools get a tryout
in Denali
Combatting pavement roughness with ROSAN
How well do you know your asphalt
mix design?
The ABCs of heat-straightening repair
for steel bridges
Highway technology calendar
