Aggregates Manager Digital Magazine
Issue link: http://read.dmtmag.com/i/932759
Bill Langer is a consulting research geologist who spent 41 years with the U.S. Geological Survey before starting his own business. He can be reached at Bill_Langer@hotmail.com CARVED IN STONE 40 AGGREGATES MANAGER / February 2018 D uring February 1998, I wrote an article for Aggregates Manager with the same title as this article. Here we are, 20 years later, still waiting for that significant increase in highway funding. Just for the heck of it, I did some back-of-the-en- velope calculations to see how much aggregate might be needed to repair our highway system. I made my calculations based on how many miles of roads in each state are in poor or mediocre condition. Get a load of this. There actually is a way to mea- sure the roughness of a highway. A mile of road in good condition has an International Roughness Index (IRI) of less than 95, which means that over that mile, a meter on a test vehicle travels up and down less than 95 inches. A mile in fair condition has an IRI of 95 to 120, one in mediocre condition has an IRI of 120 to 170, and a mile in poor condition has an IRI of 170 or more. This past summer, we went camping with the grandkids, and I know we traveled a lot of roads with an IRI of 170 or more. But that's another story. Back to how much aggregate might be needed to repair our highway system. The United States has about 4,096,599 lane miles of road in poor to mediocre condition. I figured it would take about 500 short tons of aggregate to lay 2 inches of asphalt on one lane mile of highway. The map shows, relatively speaking, how much aggregate each state will need to re- pair their poor to mediocre roads. The darker the color, the more aggregate a state needs. Lucky California is the winner and needs 131,563,126 tons of aggregate, while poor Hawaii comes in last and only needs 2,335,097 tons. The grand total for the whole United States adds up to 2,050,140,246 tons of aggregate just to repair the roads in poor to mediocre condition. That's a lot of aggregate. Let me put this into perspective. During 2017, the entire United States produced 2,458,385,354 tons of aggregate. So, bringing our poor to mediocre road surfaces (forget about roads in fair condition, or the bridges, or airports, or railroads, or canals) up to snuff would require 80 percent of the entire amount of aggregate the country produces in a year. Whew! What does this mean in terms of dollars? Well, there are some really squirrely numbers out there, but $90,000 per lane mile appears to be a reliable number for a 2-inch overlay of performance-grade asphalt concrete hot mix. Aggregate goes for a little more than $9 per ton, or $4,540 dollars per lane mile, or about 5 percent of the total cost of the put-in-place asphalt. So, to repair all the roads in poor to mediocre condition would cost about $370 billion, of which about $18.6 billion would be for aggregate. Maybe that money will show up soon and some future camping trip with the grandkids will have a smoother ride. Or maybe 20 years from now, they will still be waiting for highway funding. AM While much has changed over the last 20 years, the need for a significant, long-term investment in roads has not. America's Roadways are STILL Waiting for Highway Funding