Chip seal—the bumpy truth
I rode Guanella Pass recently to enjoy the aspens. Several cycling friends, who are also Bicycle Colorado members, told me to ride the pass before it was completely chip sealed. Unfortunately, the job was complete, changing the pavement from smooth to somewhat rough. I waited too long.
For those who don’t know, “chip seal” is the process of laying down an oily, tar-like adhesive on the pavement and covering it with small stones (aggregate). The stones are compressed into the adhesive and compression continues over time with the weight of motor vehicles traveling on the road.
I have never met a bicyclist who liked chip seal, particularly when applied to a smooth road that does not seem to need repair. “Why would they do that to a perfectly good road?” we say. Personally I much prefer a smooth asphalt road over chip seal.
Until I dug into the details of transportation projects and budgets, I was quick to complain about chip seal, whether riding my bike or driving my car. Stones flying at the windshield, chips to the paint of both bicycle and car plus bouncing of bicycle and body are all unpleasant.
Why chip seal?
Effective use of transportation budgets (our tax dollars) is the answer. Wouldn’t it be great if the money existed to regularly repave all roads to keep them in near new condition?
According to the Colorado Department of Transportation (CDOT) and other transportation organizations, repaving a roadway is eight to 10 times more costly than applying chip seal. Complete reconstruction including the underlying road bed is about 25 times more expensive.
And we are talking very large dollar amounts. One mile of interstate highway can cost up to $50 million or even more for major reconstruction.
Chip seal, when performed early in a road’s lifespan (1-4 years after newly paving), results in an average of 10 years (and sometimes up to 20 years) of additional life for roads. This increase in road lifespan is significantly reduced after roads begin to crack and potholes begin to appear. As a result, we lose our smooth, new pavement within a span of only a couple years.
Without chip seal, wear and tear from vehicles—particularly heavy ones—along with sun, oxidation and freeze/thaw cycles produce cracks, then potholes.
Improvements have been made
Advocacy has resulted in a noticeable improvement to chip seal specifications. Previously, aggregate with larger stones was used in this process. Bicycle Colorado pursued a change to CDOT policy, resulting in a 25 percent reduction of the size of the stones in the aggregate. In addition, new “surface seal” alternatives to chip seal are also being piloted, like sand seal, for example.
Chip seal and surface seal will be used for the foreseeable future. I (and probably you) will be disappointed again when a new, wonderfully smooth road becomes a bit bumpy after only one or two years.
Unless hundreds of millions of additional dollars become available annually for CDOT and local governments to repave worn roads, chip seal will continue on many state and local roads. Voters in Colorado were clear in a 2013 comprehensive survey; we are not willing to pay for additional road repair and construction through any kind of additional tax. (Did you know the gas tax only funds about 50% of the cost of our roadway system? That’s a topic for another blog.)
Compared to the cost of building and maintaining roads, building and maintaining dedicated bicycle infrastructure is very affordable. One U.S. city invested 50 million dollars over several years, producing 250 miles of bicycle infrastructure (as we note above, the same amount may only pay for one mile of highway.)
In addition, bicycles cause virtually no wear and tear on roads. More trips by bicycle, coupled with strong advocacy for change by Bicycle Colorado and others will accelerate the transportation system changes we desire—toward safe, enjoyable, connected routes whether traveling by bicycle, car, transit or walking. And somehow we will figure out how to lessen the impact of preventive maintenance like chip seal on our favorite routes.