Expressways & Interstates are only designed to last for 20 years

Figure 2-5. Tonnage on U.S. highways, railroads, and inland waterways (U.S. Department of Transportation FHWA FM&O 2007).

Figure 2-5. Tonnage on U.S. highways, railroads, and inland waterways (U.S. Department of Transportation FHWA FM&O 2007).

Roads are Essential

There are 4,016,741 miles of roads in the United States.  The most critical roads are the almost 47,000 miles long with 55,000 bridges and 4 or more lanes wide Interstate Highways, the largest single investment the American people have made in public works.

Over eleven million trucks worth $1 Trillion dollars deliver goods over these roads. Trucks moved nearly 70% of all domestic freight — 9.4 billion tons of stuff. If you put all of these trucks in a line, it would stretch from the earth to the moon over 11 times.

According to the most recent information from the Commodity Flow Survey (CFS), on average, 42 tons of freight worth $39,000 was delivered to every person in the United States in 2007 transported an average of 11,000 ton-miles to every person in the country.

Since railroads are on average 4.5 to 6.5 times more energy efficient than trucks in ton miles of freight moved per gallon (Tolliver) it’s a shame, no, a crime, that there are only 140,000 miles of railroad tracks (down from 254,000 miles in 1916), just 3.5% of the 4 million road miles. Freight trains used 2% of our petroleum. Trucks burned 46% — 20% medium and heavy trucks (classes 3-8) burned 20% and 26% light trucks another (CTA).

Do you like to eat?  Here’s how grain is typically moved from point A to point B (bold represents diesel burning vehicles).  After harvesting the grain it’s trucked to on-farm storage, then trucked to a country elevator, then the grain moves by truck or train from the country elevator to the sub-terminal elevator,  then a train or barge delivers the grain to the export elevator, and the grain is loaded on a ship and taken to the destination country.

Roads are in Bad Shape

But they’re falling apart and need $930 billion of work. Driving on this poor pavement costs motorists an additional $67 billion in vehicle repairs and operating costs every year (ASCE). When you consider all the ways highways are assaulted, it’s not hard to see why.

Heavy Trucks

According to the AASHO Road Test, heavy trucks can do more than 10,000 times the damage of a car. The amount of damage varies by how fast the truck is going, how uneven the road is, and many other factors (Hjort).

Soil, weather, & exponential growth

The freeze-thaw cycle cracks, swells, and buckles pavement.  Roads fissure from heat, depressions grooved by wheels, abrasion of studded tires, water filling cracks and freezing, water and salt corroding steel rebar. Roads unravel from lost surface stones, potholes, and poor maintenance.

The amount of traffic today is often more than double what the road was originally designed for. No one thought freight would move from trains to roads given how much more fuel efficient trains are, and engineers can’t anticipate the new suburbs and shopping malls that flood highways with more vehicles.

Local materials affect longevity

Concrete is the most heavily used substance in the world after water (Sedgwick), which is why gravel, crushed stone, and sand are the leading items transported by weight – one in seven tons of freight. But they don’t go far, the average distance moved is 60 miles, because the shipping is so expensive and their value so low.

This means that often less than ideal local material is used to make concrete.

Roads are two to four foot thick cakes, with six layers (Subgrade, capping, sub-base, binder course, and the frosting is the surface course). Each layer is baked with local materials, and never with the same recipe — there are an infinite number of recipes. Adding to the limitless permutations is what kind of steel is used, since steel varies in what alloys were used, and how strong, resistant to corrosion, and easily welded it is. Asphaltic concrete only adds to the mystery, since it has an unknown chemistry brought in by the source of the crude oil it was derived from (Skinner).

Roads can last longer

They’re designed to last for 40 years in some European countries with thicker, more durable roadbeds using concrete rather than asphalt. Concrete lasts longer, but it costs more and takes longer to repair. Asphalt is cheap and fast, but falls apart quickly.

Longer Lasting Roads are Expensive

Long-lasting roads are much thicker and cost more, which need more money up front, and taxpayers tend to object to that. Look what it took to make Chicago’s 30-year Dan Ryan Expressway at a cost of $1 billion per 10 miles (Adams):

  • Old road: 27 inches thick. 12 inch aggregate., 10 inch concrete. 5 inch asphalt.
  • New road: 44 inches thick. 24 inch aggregate. 14 inch concrete. 6 inch asphalt.

The United States has numerous agencies who’ve come up with ways to build longer lasting roads, but this often requires new equipment, which small construction and paving companies can’t afford, and the majority of highway construction is done by small firms.

Highway agencies have fixed budgets, so even though it would cost far less in the long run to make a 50-year-road, they often don’t have the money at the outset to pay for a better road. Highway agencies also try to build and maintain the maximum number of miles possible and don’t want to blow their wad on relatively few miles of highway, even if that would be the best use of public funds.

There are no incentives to build long-lasting low maintenance roads. Politicians get no immediate political return from building long-lasting roads, low-bidders usually get the work so quality suffers, and financing is done by cost per mile, not durability per mile over time. On top of all that, the number of pavement design engineers is shrinking from downsizing, retirement, and young engineers not being attracted to this field.

Peak Oil – the End of Roads?

Peak oil is an awful lot like losing your job with no hope of new one ever again. It’s not a good time to buy a new car, you’ll need every penny of your savings to pay for food, housing, insurance, and utilities.

We’ve been at peak oil since 2005 and any day now could slide down the other side of Hubbert’s peak.  It’s an awful time to replace 11 million trucks worth $1 trillion dollars and millions of miles of underground pipelines that deliver diesel fuel across the nation with something else that doesn’t even exist yet.

And if you did that, then what?  The roads are falling apart.  Swift writes “Bringing the system into full repair, and keeping it there, will cost us $225 billion a year for the next 50 years to rehabilitate surface transportation. What’s at stake, ultimately, is a foundation of America’s safety, economy, and mobility since we do 96% of our traveling by car and truck. And not making the fixes will wind up costing more as needed repairs balloon into reconstruction. “If we can get this work done now,” said John Horsley, AASHTO’s executive director, “it will cost one-third of what it’ll cost if we put things off.”

Swift concludes that this highway system “represents a spectacular investment in a mode of transport that will wither without new fuel sources….Before long, we’ll be compelled to develop a wholesale replacement for gasoline. We’d better hope we do, anyway. Because without alternative fuels, we may see the interstates morph from the world’s biggest highway system into its biggest white elephant”.

A few more statistics

  • In 2008, 4.5 million people were employed in transportation and warehousing industries in the United States, a little over 3% of total U.S. employment.
  • Trucking was the largest employer within the for-hire transportation section with almost 1.4 million employed.
  • The railroad industry employed 231,000.  There are 94,942 miles of Class I freight railroad tracks, 46,474 miles of regional and shortline railroad tracks
  • water transportation employed 67,000.There are 26,000 miles of navigable inland waterways
  • Another key component of logistics services and supply chains, warehousing and storage, employed 672,000

 

References

ASCE (American Society of Civil Engineers). 2013. Report Card: Roads.

Adams, C. Dec 31, 2010. Why don’t roads last longer? StraightDope.com

CTA. Center for Transportation Analysis. 2013. Transportation Energy Data book Edition 32. Chapter 2. Energy. Oak Ridge National Laboratory.

Hjort, Mattias, et al. Road wear from Heavy Vehicles – an overview. Report nr. 08/2008 NVF committee Vehicles and Transports.

Preserving and Protecting Freight Infrastructure and Routes. 2012. National Academy of Sciences.

Sedgwick, J. 1991. Strong but sensitive. Atlantic Monthly, April 1991, pp. 70–82.

Skinner Jr., R.E. 2008. Highway Design and Construction: The Innovation Challenge. National Academy of Engineering.

Tolliver, D, et al. May 2013. Analysis of Railroad Energy Efficiency in the United States.

Upper Great Plains Transportation Institute, North Dakota State University

U.S. Department of Transportation RITA/BTS 2010, Table 3-19b

Additional reading

Gibbons, J. 1999. Pavements and Surface Materials. University of Connecticut Nonpoint education for municipal officials technical paper #8.

Keller, G et al. July 2003. Low-volume roads engineering. Chapter 12. Roadway Materials and Material Sources for Low Volume Roads. USDA Forest service.

Swift, Earl. The Big Roads: The Untold Story of the Engineers, Visionaries, and Trailblazers Who Created the American Superhighways.

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2 Responses to Expressways & Interstates are only designed to last for 20 years

  1. Fernando says:

    Maybe the best solution is smaller lighter trucks with more wheels to distribute the point loads.

    • energyskeptic says:

      maybe, but we’ve got $383 billion worth of Trucks, buses, and truck trailers, $218 billion of Light trucks (including utility vehicles), and $165 billion of other trucks, buses, and truck trailers. Do we have the energy, steel, etc to do that now that we’ve spent our energy mostly on what you see around you, and need the remainder to grow food and provide for other essential to survival functions