The FHWA and USDOT approached Carlson Paving at the 2010 World of Asphalt Show in Cincinnati with the challenge of designing and building a better class of attachment to help create a safer pavement drop-off.
Carlson Paving accepted the challenge to design and build a better class of attachment for creating a safer pavement edge.
Innovations are often born out of necessity. For the U.S. Department of Transportation (USDOT) and the Federal Highway Administration (FHWA) in 2010, the necessity for a reliable and easy-to-use device to institute the Safety EdgeSM initiative was urgent. Needing an innovative and reliable way to construct the roadway safety feature, the USDOT and FHWA approached Tom Travers, sales and marketing manager for Carlson Paving Products, with their predicament. Accepting their challenge, Carlson Paving Products created one of the most successful safety-focused paving devices in the Carlson Safety Edge, an attachment that continues to lead the way five years after its debut.
A LIFESAVING INITIATIVE
Following years of studies by the USDOT, FHWA, State Departments of Transportation, and industry groups, a correlation emerged between the amount of roadway accidents and fatalities due to departure of the vehicle from the roadway. A major contributor, they found, was the existence of pavement drop-offs left by conventional paving methods. These drop-offs created dangerous conditions when attempting to re-enter the roadway, resulting in injuries and fatalities that could otherwise be preventable.
The Carlson Safety Edge was named as one of only four devices endorsed by the FHWA for constructing a safer roadway pavement edge.
By creating a compacted, 30-degree roadway edge, the safety of roadways drastically increases by allowing easy transition back onto the roadway without tire scrubbing. While the evidence was sound and a plan put in place, the FHWA and the USDOT saw glaring issues with the attachments prior to the Safety Edge.
The most recurring issues with Safety Edge attachments were in adjustability, performance, and mounting of the devices. Prior to the Carlson Safety Edge, devices were solely positioned inside the extension. This mounting position created many problems, most notably the buildup of asphalt around and in the devices that disrupted adjustability and performance. The positioning also meant that operators found adjusting the device’s height difficult, a major problem due to the need to lift the device when approaching driveways and other obstacles.
It was the compaction issues, however, that the FHWA and USDOT found most worrying about existing devices. While the edges would look adequate prior to compaction, once the rollers passed over, the edges would deform. It was at this point the FHWA and USDOT approached Carlson at the 2010 World of Asphalt Show in Cincinnati with the challenge of designing and building a better class of attachment, one that could be relied upon and help promote the safety initiative.
THE CARLSON SAFETY EDGE STORY
Immediately upon returning from Cincinnati, Travers and the engineering team at Carlson set to work in creating a device that would accurately produce 30-degree roadway edges while taking into account the issues with the designs of the time. After just 30 days of design and build, the first generation of Carlson Safety Edge was born with immediate contrasts to previous attachments.
"We placed it on the endgate where it belongs," recounted Travers. "By placing it there, we created a design that was more comfortable to come in and out with ease." The endgate-mounted Carlson Safety Edge incorporated a center jack to raise and lower the beveled edger from 30 degrees to joint matching. Whereas the devices before it were difficult to adjust or inaccessible due to material buildup, the Carlson design allowed operators to easily adjust the exterior-mounted endgate jack.
The patented device was quickly taken to jobsites for testing and presentation before government officials and paving contractors. The performance differences between existing devices and the Carlson Safety Edge became clearly evident. While devices that were mounted inside the extension acted merely as strike offs, the Carlson design extruded and sealed the edge for a cleaner, more compacted edge. The added density to the edge also drastically improved the life of the edge when undergoing compaction. The edge produced by the Carlson device continued to hold and retain its 30-degree angle after roller compaction.
Following the six tests performed that year, Travers and the team at Carlson knew they had a platform for success. Yet while the first year of testing had shown the superior design and performance of the Carlson Safety Edge endgate over other devices, Carlson still saw room for improvement. The following year, heat was incorporated into the design to improve material extrusion, the beveled shoe was narrowed, and the center jack was placed inside a strengthened frame.
As soon as the paving season started up in 2011, the second generation of the device was sent out to seminars and jobsites across the country. "Some of these seminars we participated in saw up to 150 participants," recalled Travers.
The volume of interest in the safety initiative, combined with an easy-to-use and reliable design in the Carlson attachment, continued to grow throughout the year. Following input from contractors and acknowledging the need to make the platform universal for all screeds for the good of the industry, minor modifications were made to create a third generation of attachment. By this time in 2011, most states had begun to institute Safety Edge as a requirement on projects while the Carlson Safety Edge was named as one of only four devices endorsed by the FHWA for constructing the roadway safety feature, a designation it continues to maintain.
Carlson sees the V3 platform as a springboard in advancing innovative and safety-driven attachments.
AN EVOLVING PLATFORM
Always seeking ways to advance innovation, safety, and performance in the industry, Carlson continued to look at different ways to enhance the Carlson Safety Edge and its platform. By 2013, the device had become a hugely popular and successful attachment, both commercially and in regards to improving roadway safety. "The only issue that we saw with the V2 platform," Travers explained, "was that the design was still bulky. As a safety issue, we wanted to better protect crews from the weight of the endgate. That is when we came up with the V3 design."
Introduced in 2013, the V3 platform was designed to replace runners that attached to the endgate through use of an integrated bolt system. Rather than replace entire endgates, operators would be able to replace much lighter runners and be able to switch quickly between a joint matching runner and a Carlson Safety Edge runner.
The V3 drastically improved the safety of crews and increased productivity, and the platform’s potential was quickly acknowledged as a basis for future safety initiatives. In 2014, Carlson introduced longitudinal joint density attachments that helps improve the overall lifecycle of roadways, with the Sideload Endgate Attachment utilizing the V3 platform. With a solid foundation upon which to build, Carlson sees the V3 platform as a springboard in advancing innovative and safety-driven attachments.BACK TO ISSUE
LOOKING FOR MORE ARTICLES LIKE THIS?
Astec’s Greg Painter wears many hats while assisting his customers
North Carolina asphalt producer upgrades plant control system to meet growing customer base