Asphalt highways, gravel roads and the pig manure answer

One of the problems that the rising price of crude has created lies with the related cost of asphalt. As a result states are being more creative in spending their repair budgets, and it is interesting to see some of their answers. Asphalt is used extensively in creating the roads that we drive over every day. Because of this traffic, and movement of the underlying material, roadbeds can fail and erode. But not all do, at least to the extent of the majority. Just this last week the Asphalt Pavement Alliance has announced the winners of this years Perpetual Pavement Award. The winners have to be the owners of asphalt pavements that are at least 35 years old and have never had a structural failure, and the average time between resurfacing has to be no less than 10 years. There are ten awardees, with sections of highway that won being found in Alabama, Arkansas, Kentucky, Michigan, Minnesota, Mississippi, Missouri, Nebraska, South Carolina and Tennessee. The winners range in length up to 12 miles, and from Interstates to State Roads.

Asphalt has been getting more expensive, as the price of crude oil increases, and this reflects back to the state highway departments that must repair damaged roads.

In Illinois, for example, the average asphalt overlay will last between five and eight years (Illinois State Toll Highway Authority) or eight to fifteen years (Illinois Department of Transportation). The decision on repair is a function of both the amount of damage, and the amount of traffic. One consequence of this is the return from asphalt coated to gravel roads. Ugo Bardi recently commented on this at The Oil Drum. He noted that an early use of the Canadian Tar Sands was as a direct application as a roadbed material, and the same has been considered for the West Indies.

Asphalt is one of the most re-circulated of materials, since the material that is laid into the roadbed is only about 5% asphalt and 95% aggregate, so that when the original surface is removed as part of the resurfacing operation, about 80% of it is recycled. And it is not just the aggregate, and some of the binder that gets recycled.

Starting in 1994 Florida DOT has also mandated that the mix include recycled ground tire rubber.

From 1994 through 2007, Florida has recycled the equivalent of over 12.5 million passenger tires into asphalt pavements, saving valuable landfill space while improving the performance of our highways. That works out to over 471 passenger tires per lane mile. Current research shows benefits of combing both ground tire rubber and high tech polymers to improve asphalt binders even more.

Because of the changing price of oil, most states have an adjustment index for the price of asphalt that their construction contractors buy (and then charge the state for).

Some states are returning roads back from asphalt to gravel, though this is not as easy as it may at first appear, since the construction of the roadbeds is different, as is the maintenance, since a gravel road is graded back to quality, rather than being ground up and resurfaced. This is particularly true when road traffic is light, but a number of states are moving this way because of budget constraints.

Thirty-eight counties in Michigan replaced a total of 100 miles of asphalt roads with gravel because of decreasing funds in 2008-09, said Monica Ware, a spokeswoman for the County Road Association of Michigan.

In Montcalm County, Mich., 10 miles were converted to cut patching costs in 2009, said Randy Stearns, managing director of the county's road commission. He cited one road that cost a combined $39,244 in 2008 and early 2009 for patching, but only $7,300 to crush into gravel. More roads may be converted this summer, he said.

The relative costs of going from gravel to asphalt indicates that the transition comes at around 200 vehicles/day.

Relative costs for different road types (U of Minnesota )

Now the price of asphalt is anticipated to rise again, and so what are states to do? In Missouri, a state that grows a lot of pigs, – mainly in farms, though there is a concern over the rising numbers of feral hogs in the state. Putting the problem of disposing of a lot of porcine waste with the high cost of asphalt, folks in Missouri, at the highway leading into Six Flags at Eureka (just outside Saint Louis) have taken the logical next step.

The witnesses lining the bright stretch of North Outer Drive along Interstate 44 — particularly those with noses and an abiding interest in sustainable technology — won't soon forget the moment the red dump truck deposited a 15-ton load of the designer asphalt into a road paver late Wednesday morning.

"Whew!" gasped a worker with Pace Construction Co., the St. Louis County road contractor that joined forces with Innoventor, the Earth City-based engineering and design firm that perfected the process of converting the animal waste into a bio-oil used in asphalt binder.

To others, the air swelled with the sweet smell of potential for new manufacturing opportunities, jobs and, possibly, profits.

The initial stretch of road treated was some 500-ft long, and will get a significant seasonal traffic from the amusement park, accelerating wear potential and allowing the evaluation to be made in a shorter time.

The process was thought up and developed through Innoventor. Essentially the animal waste is converted into a bio-oil that can serve as the binder in the asphalt. The program is currently getting the close attention of the Missouri Department of Transportation, as well as the U.S. EPA. (And I suspect that the next time I drive by the site, I may roll down a window and have a quiet sniff).

It takes all kinds, to find the right answers.

Highway maintenance concerns

One of the things that struck me in my recent trip to China was the vigor with which the state was driving highways (with associated tunnels and viaducts) up through the mountains to access and connect some of the more remote communities in the hinterland. It is a very expensive undertaking, and yet it reminded me of the words of a history colleague who noted that it was the development of the roads and the automobile that really opened up America and liberated a large part of the rural population and brought many benefits to the country.

I mention this because there is a quietly increasing cost that is threatening that continued access and that is likely to have a negative impact in the near future. It was the subject of today’s editorial in The Kennebec Journal under the headlines “Is Maine maintaining too many roads?” The State has 8,500 miles of road and the question has been asked:

"Is 8,500 miles too much road system for us to afford and do too many of those roads go through too rural areas of Maine, and the cost of building them to standards too high or even maintaining them, and should we just decommission a percentage of the roads?"

It is a question that is not unique to Maine, many of the more rural states with low populations are faced with the rising costs of road maintenance and the increasing price of asphalt and other repair materials, not to mention the bridges and other infrastructure. In the short term there are some funds coming from the stimulus package that might help with the odd project, but that is a “one-shot” deal that cannot hope to address the size of the problem.

"These bridges and highways serve as critical links for Maine communities, and every day that we let them fall into further disrepair costs us lost lives, lost income and lost economic potential," says economist Laurie Lachance, head of the foundation.

But one could substitute the name of a number of states and still have the sentence be true. Partly, as the article notes, the increased costs come from a previous commitment to upgrade rural roads perhaps beyond the point that usage would justify, but that being the case, has the time come to start stepping backwards? For even in more urban states, the problems are merely growing with time. Consider Michigan where a State Senator notes

For one, the federal stimulus package is bringing in $847 million in additional one-time revenue designated for surface transportation purposes. Unfortunately, state-owned highways and expressways are getting the lion's share of the funding, with our county and municipal roads receiving only a fraction.

But the federal stimulus package still presents an opportunity. Remember that the state is receiving up to $7 billion in additional federal stimulus funding over a two-year period. This could free up other state-generated revenues to be used for our infrastructure needs.

The size of the problem is, however much larger, and in the smaller communities where roads must be resurfaced, budgets are getting stretched and roads are converting back to gravel. In cities however that is not an option, and projects are being scaled back as the cost of asphalt must be met. Hope, Arkansas is an example

“About two years prior to (2005), we were paying in the range of $30 per ton,” (City Manager) Cook told the Hope City Board of Directors recently.
In a recent bid opening for hot mix to be used in this year’s street program, the City agreed to pay $114.50 per ton to low bidder Charles Lindsey, of Ashdown. The only other bid at $145 per ton was submitted by Sid and Sons, of Texarkana.

Cook admitted to a certain surprise at the disparity.
“We were projecting that asphalt might bid out as high as $130 per ton,” she said.

Rural bridges are equally a part of the problem, Missouri, for example, has more than 10,000 bridges of which more than 1,000 are in need of repair. However, outside of the stimulus, the state is funding a program, known as Safe and Sound .

Safe & Sound is a multi-faceted program that will improve more than 800 of Missouri’s worst bridges in five years. Safe & Sound will prevent many of the state’s worst bridges from being closed temporarily or permanently for safety reasons.

The program is funded through a bond program that the state runs. Other states are not that fortunate.

Of the nearly 600,000 highway bridges in the country, 24.1 percent were reported deficient and/or functionally obsolete in 2006, a minor improvement from 2005 when 25.5 were deemed deficient. At the current rate of repair it will take 62 years for today's deficient bridges to be brought up to date.

With the rising prices of repair materials both roads and bridges will need levels of funding support that is not likely to be available. Of course this is not just a problem in the Unites States, but countries around the world will continue to address the problem, and many will not have the resources of China.

So conditions, in countries such as those in Gambia, will continue to be so bad as to inhibit pregnant women from visiting health centers (for example). It is not likely that rural conditions will get that bad in America that communities become cut off in this fashion, yet the marriage of cars and highways require that both be maintained, and one is not that useful without the other. And in the end both, at the moment, depend on the availability of oil, at a reasonable price, a condition that is decreasing, again, in probability.

And lest you wonder at the pause in posts of the last few days, Owen William came into our lives, and is our first grandchild. We thus had other things on our minds.