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Georgia Tech Develops Automated Crack Detection, Sealing System

Sealing cracks in roadways ensures a road’s structural integrity and extends

the time between major repaving projects, but conventional manual crack

sealing operations expose workers to dangerous traffic and cover a limited

amount of roadway each day.


To address these challenges, the Georgia Tech Research Institute (GTRI)

developed a prototype automated pavement crack detection and sealing system

with funding from the Georgia Department of Transportation. In road tests,

the system was able to detect cracks smaller than one-eighth-inch wide and

efficiently fill cracks from a vehicle moving at a speed of three miles per



“Our prototype system has proved in many ways that a commercial-scale

automated crack sealing system is viable,” said Jonathan Holmes, the GTRI

research engineer currently leading the project, which began in 2003. “We

demonstrated solutions to technical challenges -- including the high-speed

firing of nozzles, automated crack detection and navigation -- in a

real-time, limited-scale system.”


An automated crack sealing system would increase the level of safety for the

workers involved, require fewer personnel and increase the amount of roadway

covered per day. In addition, the system could save transportation

departments money because sealing cracks extends the time before a roadway

needs to be completely repaved.


The prototype system, which was mounted on a trailer, consists of a stereo

camera, light-emitting diodes (LEDs) of two different colors, and an

assembly to provide a continuous supply of sealant to longitudinal and

transverse sealant distribution systems. The operation required only one

worker to drive the vehicle pulling the trailer.


As the system traveled along a road lane, the LEDs illuminated the road in

two directions -- parallel and perpendicular to the road -- and the stereo

camera took two pictures of the road simultaneously, which were analyzed

using thresholding and filtering algorithms. Within 100 milliseconds of

taking the images, the computer onboard the trailer generated a “crack map”

specifying the location and shape of any cracks shown in the images.


Based on the cracks found in the image, the master controller instructed the

sealant applicator valves when to fire. To fill longitudinal cracks, a

single dispensing nozzle capable of continuous operation was attached to a

linear servo axis. The transverse sealant distribution system consisted of

12 nozzles spaced evenly across one foot. The transverse and diagonal

distribution prototype was intended to represent one module that could be

replicated and joined together to service a full-width roadway lane.


In multiple road tests, the prototype system proved to be a successful

proof-of-concept for the automation of crack sealing operations.


Before a full-scale system can be successfully implemented by transportation

departments, several issues must be addressed, according to Holmes. First,

the crack detection algorithm will need to be improved. The researchers

tested their crack detection algorithm on more than 100,000 images they

collected of cracks on state roads and found the program correctly

identified more than 83% of the cracks.


“Our crack detection algorithm was limited because we used a vision-based

system, which was confounded by regions of high contrast caused by features

other than pavement cracks, including dark stains in the pavement, lane

stripes, raised-pavement markers, crack sealant and debris,” said Holmes. “A

full-scale system may require a fusion of multiple imaging sensors, such as

a 3-D laser scanning system.”

Holmes also suggested changes will be necessary in the way the sealant was supplied to the longitudinal and transverse distribution systems before a full-scale system can be realized.

Information provided by the Georgia Institute of Technology Research News & Publications Office. David Jared, acting chief of research & development at the Georgia Department of Transportation Office of Materials and Research, and GTRI principal research engineers Wayne Daley and Wiley Holcombe, research scientist Colin Usher, and research engineers Sergio Grullon and Steven Robertson also worked on this project.


PMSI Acquires Clayco Midwest

Paving Maintenance Supply Inc. (PMSI), a Crafco company, has acquired the assets of Clayco Midwest Co., Granite City, IL. Don Brooks, president of PMSI, said the acquisition combines the assets of one of Crafco’s long-standing distributors with PMSI to expand PMSI’s store locations, sales and service to Southern Illinois, eastern Missouri, and Kentucky.The Clayco Midwest location in Granite City becomes PMSI’s ninth store location.

Barry Barber, president and owner of Clayco Midwest, will stay on as branch manager for the region with assistance from Carrie Blair and Robert Martinez.


Schwarze Names Heyer VP Sales

At Schwarze Industries, Hunstville, AL, Greg Heyer is vice president of sales and marketing. He joins the company from Heil Trailer International where he served as global vice president of sales, marketing and customer service.

Also at Schwarze, Joe Hendrickson is national sales manager, Kevin Lozen is plant manager, Lance Wolf is design engineering manager, and Neil MacLeod is managing director for Schwarze Australia Pty Ltd.