I don’t know about the rest of the country, but here in Northern Indiana, the main method of secondary, and sometimes primary, road repair is a process called “chip seal.” A wet, hot, sticky layer of bitumen, tar, or asphalt is sprayed onto an existing paved roadway and then a layer of fine aggregate (fancy name for pea stone) is spread on top of it. In the better applications it is then rolled to compact the stone somewhat into the asphalt. In most applications, at least in my neck of the woods, it is merely spread, not necessarily evenly, on top of the asphalt and then the resultant automobile traffic does the job of compacting over a period of time. At least in theory.
The main, and maybe only, advantage to chip seal versus more durable and finished road resurfacing, is it’s cost. The initial resurfacing is three or four times cheaper than other methods in most cases.
The major downside to chip seal, from the local road maintenance point of view, is that it does not last nearly as long as other methods. This leads to a debate over short-term versus long-term effective cost analysis. I tend to side with the anti-chip seal viewpoint. I would rather see a smaller number of rural roads repaved or properly resurfaced every year than see a larger number of them chip sealed. The long-term cost savings, not to speak of the true improvement of our road system, weighs heavily on the side of systems other than chip seal.
I oppose the use of chip seal on several other grounds as well. First is that while chip seal may, in the short term, repair minor cracks and seal out water, it provides absolutely no structural strength to the roadway. Therefore, it is more about cosmetics than it is about structural integrity. That’s why the same roads are chip sealed year after year.
Secondly, as anyone who has driven on a freshly chip sealed road can testify, it vastly decreases vehicular safety in that the loose gravel that is a signature of chip seal rolls under automobile tires, causing the car to track irregularly and to handle very unsafely. This effect can be improved somewhat by reducing speed on a freshly chip sealed road surface, but can still be taxing even to the most skilled driver. And don’t even try navigating a freshly chip sealed road on a motorcycle or a bicycle.
Another reason that I oppose chip seal in general is the dust that becomes airborne from traffic traversing a road with a fresh application of this treatment. The cloud of dust that emenates from such a roadway can greatly reduce visibility, adding to the unsafe conditions of proper handling mentioned above. The resultant cloud also coats everything in its windborne path with a patina of fine dust. Many’s the resident who has to hose down his house, wash his vehicles, and rewash and dry hanging laundry due to thoughtless chip seal projects. This dust also poses a health hazard to anyone with asthma, dust allergies, and even those of us with no particular predeliction toward these chronic problems, due just to the shear volume of dust often involved.
What is the cost to the taxpayer who has to visit the doctor or local emergency room with an asthmatic or other allergen based reaction to chip seal dust? Probably more than the cost savings to the county over using more permanent, less invasive repair methods. Certainly when you factor in the added costs to the individual taxpayers to repair stone chips in automotive paint or to replacing windshields damaged by flying gravel, this would be even more true.
There is also a high incidence of emissions of volatile organic compounds originating from the chip seal base. These airborne toxins can be smelled by anyone in proximity to a fresh chip seal job, whether those living on roads so treated or those driving on these roads. These volatile organic compounds can also induce asthmatic or allergic reactions, as well as headaches, nausea, and other immediate responses. It is not clear what the longterm health consequences may be to exposure to these materials, but I doubt that it will add to the quality of life for anyone exposed to their vapors.
As applied in my area, chip seal is almost consistently over applied, which only exacerbates the negatives earlier noted. That means more volatile vapors from the base coat, more dust from the gravel, and more dangerous driving conditions. It also means more clogged drainage ditches and sewers from all of the over applied gravel that leaves the roadway and ends up in those adjacent areas. That means that local tax dollars must then be expended to undue some of the damage done by using this “cheap” fix. It sounds like a zero sum situation to me, all things considered.
Every year when our local road crews begin applying chip seal I fire off complaints to commissioners, the road commission, and local newspaper editors citing the above, more general concerns, as well as specific and personally anecdotal issues. Does it do any good? Not to my knowledge. But I still feel better everytime that I rant about this topic. Maybe if more of us complained about chip seal we would see it either used more sparingly, applied correctly more often, or even ended altogether. I can only hope.