Summer 2003 infoCycling

Caltrans—thinking outside the box when it comes to recycling, reducing, and reusing

The California Department of Transportation (Caltrans) is the State’s manager of interregional transportation services. Caltrans professionals either work in headquarters or in one of their 12 district offices, 13 laboratories, or 304 maintenance stations throughout California. Civil and system engineers, maintenance workers, planners, environmental specialists, managers, and administrators comprise the approximate 23,000 Caltrans employees. Together these employees make recycling a reality. 

Caltrans recycles a wide variety of materials such as:

• Concrete, asphalt, scrap metal, salvageable items, and tree trimmings from its construction and maintenance projects.
• Used tires from Caltrans’ vehicle fleet and other sources.
• Paper, cardboard, special plastics, and toner cartridges from headquarters, the district offices, laboratories, and maintenance shops.

The California Integrated Waste Management Board’s 1999 Solid Waste Characterization Study estimates that 12 percent of landfill mass is generated from construction and demolition operations. Through highway improvement projects, such as the reconstruction of old roads and bridges and the creation of new ones, tons of concrete, asphalt, and scrap metal are generated.  As a good steward to its resources, Caltrans is able to divert much of this construction by-product from entering into California landfills through a variety of methods.

For example, when maintenance crews repair roadway surfaces, replacing the existing pavement is sometimes required.  As the old asphalt is removed from the highway it can be reused as shoulder backing. Shoulders provide motorists with a place to pull over during an emergency. 

Similarly, when concrete is removed, it can be crushed and used as aggregate base material underneath roadway surfaces.  Concrete can also be reused for erosion control or riprap. (Riprap is the term used when concrete or crushed rock is used to stabilize an embankment or soft ground.) Recycling activities are not limited to the concrete and asphalt generated. Caltrans also uses every opportunity to salvage items, such as guardrails, light standards, and light fixtures.  When these items are removed from highways, they are stored at salvage yards and used at a later time to replace damaged ones.  Metal items that cannot be salvaged are placed in scrap metal containers.

Some examples of items collected include old damaged highway signs, twisted metal posts, and car bumpers left along the highways. Caltrans made arrangements with contractors to pick up these scrap metals for recycling.

Caltrans works in partnerships with various businesses throughout the state. An example of these partnerships can be found with Caltrans District 4 (San Francisco-Bay Area District) and the Oakland Zoo.

The maintenance crew for District 4 is responsible for maintaining and trimming a variety of plantings within the highway right of way.  Trimming the tropical acacia tree is just one of their duties. As the acacia trimmings are a favorite treat for many animals, District 4 routinely provides the Oakland Zoo with trimmings to feed their giraffes, camels, chimps, and elephants. This partnership is economical and rewarding for both parties. Please see photo below.

Select the picture to view full size (55 KB)

Caltrans has actively pursued incorporating used tires into transportation projects. Used tires are acquired from Caltrans’ vehicle fleet and other sources. One example is the specification and use of rubberized asphalt concrete (RAC) for pavement application. RAC is produced by grinding rubber tires into very small particles.

Another very promising approach being implemented is shredding tires and using the tire shreds as lightweight fill material for highway embankments and behind retaining walls. Caltrans used 660,000 shredded tires along State Route 880 in Milpitas (Santa Clara County) as fill material for the construction of a new highway embankment.

Not only do these activities reduce the volume of tires that once would have been sent to landfills, but they have also been shown to be more cost-effective.  For example, the cost of using tire shreds for lightweight fill material is approximately $25 to $40 per cubic meter compared to the cost of using conventional lightweight fill material at approximately $50 per cubic meter.

Caltrans like so many other State agencies, local governments, and private businesses promotes office recycling. Office recycling activities include office paper (white, mixed, and newspapers), old telephone directories, and cardboard.  In addition to recycling office paper, empty laser toner and inkjet cartridges from copiers and printers are returned to manufacturers for reuse.

Caltrans is another example of a department that is a good steward of resources and one that recognizes the importance of forming partnerships with local communities. Caltrans is able to accomplish so much because it is an agency that thinks outside of the box when it comes to recycling, reducing, and reusing.

If you would like more information on these Caltrans diversion projects, contact Jack Ezekiel of Caltrans at (916) 651-8254 or Pat McDermott in the CIWMB’s State Agency Assistance section at (916) 341-6221.

Last updated: October 26, 2007