Every Day is Earth Day
STATEWIDE – Colorado Department of Transportation workers manage and maintain the state's highway system every day of the year. Plowing, patching, paving and rebuilding—these are all CDOT activities the public is well aware of. For Earth Day, CDOT announces some of its environmentally-focused activities that may go somewhat unrecognized.
"CDOT has always had a strong environmental ethic, with experts who handle all levels of testing, mitigation, protection and clearance processes," CDOT Chief Engineer Tim Harris said. "Earth Day provides a great opportunity for us to remind citizens of our department's environmental stewardship that's under the radar—including a few things the public can get involved in."
Aside from ongoing construction-related environmental work, CDOT utilizes various technologies and programs to minimize its environmental impacts, save resources and clean the environment. Here are a few examples:
Reusing asphalt on highway resurfacing projects
"Asphalt pavement is the nation's most widely recycled product," CDOT Materials & Geotechnical Branch Manager Jim Zufall said. "The use of reclaimed asphalt pavement (RAP) saves valuable aggregate resources."
Zufall points out there are plenty of construction aggregates (rock material suitable for asphalt mixes) in the ground, but there are fewer aggregate sites that can be permitted for extraction. RAP contains aggregates that have already been acquired, permitted, blasted, loaded, crushed, screened, stockpiled, reloaded and hauled.
Contractors may use a specified percentage of RAP in their asphalt mixes. In 2011, CDOT contractors used 134,000 tons of RAP in asphalt mixes on paving projects statewide—a 600 percent increase over 2007 (when 19,200 tons were used). The practice not only saves on asphalt aggregate material but also the asphalt cement binder used to mix with it.
"In addition to the aggregate resource and cost savings of RAP use, CDOT also saved an estimated $1.6 million in binder alone," Zufall said. "The use of RAP saves time, money, energy and resources."
In addition to the use of RAP in asphalt mixes, CDOT also performs on site (and in-place) reuse of existing asphalt pavements through the use of cold-in-place recycling, hot-in-place recycling and full depth reclamation processes. In a typical year, cold recycling processes used by CDOT contractors enable the department to reuse 95,000 tons of asphalt; and hot recycling processes reuse 140,000 tons.
During the past 2011 construction season CDOT saved $11 million over the use of new asphalt by instead using these hot and cold recycling processes, as well as full-depth pavement reclamation (pulverizing the roadway pavement and base aggregates, then overlaying with new asphalt pavement).
Reusing recycled or reclaimed concrete
In an average year CDOT uses about 70,000 tons of recycled concrete as aggregate base course (material under the top layers of pavement). CDOT also allows contractors to use fly ash—a waste product from coal-fired power plants—to be substituted for cement in concrete mixes. This results in approximately 20,000 tons of fly ash used each year, which, in turn, means 20,000 tons of cement were not produced and thus there was an equal reduction of CO2 emission of 20,000 tons.
Last year, the use of 20,000 tons of fly ash as a replacement for cement in concrete projects saved CDOT approximately $1 million.
In addition, CDOT is partnering with industry to develop specifications that could ultimately lead to even greater reductions in the amount of cement required in concrete mixes.
Researching More Greening Opportunities
CDOT has continued to research the use of rubberized binder in its asphalt pavement. If successful, the department will continue to help reduce the number of waste tires in the state.
CDOT is continuing research that will enable the department to switch from having concrete "recipes," so to speak, to performance-based specifications. This will allow CDOT contractors to develop concrete mixes that have lower cement content but that will still meet performance requirements.
CDOT completed the first Reclaimed Asphalt Shingle (RAS) project on US 36 (northwest Colorado) in 2011. The asphalt mix for this project contained 3 percent RAS by weight of mix. Thus far the RAS mix is showing equal results to the regular asphalt control section.
CDOT continues to implement warm-mix asphalt in the state. A total of eight technologies and ten contractors have been approved to utilize this process. Warm mix asphalt is produced at temperatures approximately 50 degrees cooler than hot mix asphalt. This process reduces the amount of fuel required to heat the mix, producing cost savings and lower CO2 emissions.
Finally, CDOT has funded a research project at Colorado State University that will investigate the use of ground-up tire rubber in highway embankments to control expansive soils. A successful outcome of this research may allow CDOT to find another beneficial use for scrap tires that would otherwise be buried in a landfill.
Improvements transportation for bicyclists and pedestrians
Colorado has approximately 1.5 million active cyclists. Additionally, there are nearly 700,000 bicycling tourists each year. CDOT, often in coordination with local agency partners and sometimes private entities, continues efforts to encourage non-motorized modes of transportation and construct or maintain the systems that support this. Some examples of upcoming initiatives include:
- Fairplay/Alma: Repaving the five-mile bike path between the two towns, parallel to SH 9, in May and June.
- Genesee/Evergreen Parkway: Construction of a new, two-mile bike path between the Genesee Interchange & Evergreen Parkway. This is the last segment between Denver and Glenwood Springs where cyclists still must use I-70. Construction is scheduled to begin this fall and will be complete in spring 2013.
- Vail Pass: Repaving the western segment of the Vail Pass Recreational Path, parallel to I-70, in late summer and early fall.
- Fruita: Construction of a multi-use concrete trail along the Little Salt Wash from north of US 6 in Fruita to the James M. Robb – Colorado River State Park. It includes an underpass beneath I-70, US 6 and the Union Pacific Railroad tracks. It also includes other trail connections and amenities. Work is scheduled to begin in the late fall.
- Durango: Implementation of a bike detection system in Durango, allowing bikes to trigger traffic signals without pushing the pedestrian button. Its success at US 550 and Trimble Lane provided the impetus to expand the system at the US 550/9th Street and US 550/22nd Street intersections this spring.
- Ridgway: Pedestrian improvements in Ridgway, including an extension of the town's eight-foot path east across US 550 to locations outside of downtown. The project will provide ADA (Americans with Disabilities Act) access from the existing path at US 550 and SH 62 and new pedestrian push signals. Construction takes place this fall.
- Arapahoe County: CDOT provided a portion of the funding for a new underpass at the High Line Canal/Iliff Avenue intersection, allowing users to safely cross under Iliff. Construction is expected to be completed this spring.
For additional information about bicycling in Colorado, please visit the following websites:
CDOT - www.codot.gov/programs/bikeped
Bicycle Colorado - www.bicyclecolorado.org
Keeping our roadsides clean
Last year, CDOT disposed of 93,683 cubic yards of trash off state highway right-of-way with the help of 9,072 Adopt A Highway volunteers, and another 6,325 bags of trash with the support of 48 corporate sponsors.
Roadside litter costs millions of dollars annually to control and CDOT relies on the volunteers who participate in the Adopt A Highway and corporate sponsorship programs to get the job done. Generally, the adopting group agrees to pick up litter from both sides of a highway for a two-mile section at a minimum of four times per year. However, each segment has its own special needs, and some groups have adopted several sections of highway. The program is easy to join at: www.codot.gov/programs/adopt-a-highway.
CDOT staff recycles used electronics and more
CDOT hosts an annual electronics recycling event each year at its headquarters building in Denver. Staff and family members are encouraged to bring in all appropriate items (e.g., DVD players, VCRs, stereo equipment, fax machines, computers, etc.) for recycling. Last year, the effort resulted in the collection of 3,721 pounds of electronics for recycling and staff are hoping to exceed that amount this year. Also, CDOT participates in the Writing Instruments Brigade® through Terracycle®. Employees contribute used writing utensils in green boxes set up throughout the department and denoted with "The Write Path" symbol. For each approved (recycled) writing instrument received, CDOT will be awarded a payment of $0.02 towards Helping Hand, CDOT's 501c3 organization, which financially helps any current or retired CDOT employee who has had a life-changing event.
