Concrete or tarmac?

 This is a technical nerdy blog mostly lifted from the 'net. Read at your peril.

To infinity and beyond!

Driving the Great American Highways, I've been struck by the difference in roads. Some are a delight, the wheels of our bus thrumming happily as we smoothly round corners and glide up hills.

Then there are the difficult ones, with adverse cambers, ruts, monotonous banding thumping away on the tyres and noise from grooves cut into the concrete. (I'm thinking especially of the i75 up to Detroit here.)

This is not really typical. Blame the Satnav.

And that's the thing. In America a lot of the roads are concrete, many more than in Europe. So as I sat behind the wheel gazing at the road, I got to wondering why.

Our next McDonalds supplied the answers I wanted on the internet - sort of.

It all depends who you ask. If it's the Concrete Paving Association of Minnesota, then concrete is king.

The following is lifted straight off the web sites:

Concrete vs. Asphalt

Following are the benefits of concrete which may surprise you! 

Concrete costs less in the long run

► Federally funded studies show that concrete Interstate pavements cost 13-28% less in the long run than asphalt Interstate pavements.

► Recent U of M studies in Olmsted and Waseca counties show that the use of concrete pavement saved up to 19% in the long run over the cost of using and maintaining similar asphalt roads.
► The same studies shows that maintenance costs were reduced 75% when concrete was used to pave roads in these counties.
► Advancements in concrete technology have reduced the cost of concrete paving while improving performance greatly; advancements in asphalt technology (so-called "SuperPave" mixtures) have increased paving costs significantly (even before considering skyrocketing oil prices) with only modest increases in performance.

Concrete lasts longer with less need for maintenance and repair

► No potholes - so concrete pavements stay smoother longer.
► No ruts form to fill with water and cause wet weather accidents. Fewer traffic interruptions for repair and maintenance.
► Mn/DOT reports that the average life expectancy of their concrete pavements is 27.5 years before repair while asphalt pavements have an average life expectancy of only 15.5 years before repair.
► Federally funded studies show that concrete Interstate highways around the U.S. last about 2.5 times longer on average than asphalt Interstate highways.
► New Minnesota concrete pavement designs are expected to last for 60+ years with minimal maintenance.

Concrete costs less for users, too

► Heavy trucks get up to 20% better mileage on concrete.
► Better long-term performance means fewer interruptions and lower user costs.
► Concrete roads are not subject to spring load restrictions that increase the number of truck trips or driving distances.

Concrete is quiet

► After years of testing and research, Mn/DOT has adopted concrete paving designs and techniques that make concrete roads as quiet as most asphalt roads, while maintaining superior skid resistance.

Concrete is safer

► Concrete provides better and longer lasting skid resistance.
► No rutting or potholes to cause loss of vehicle control.
► Concrete offers better visibility on rainy nights.
► Concrete is generally less slippery in wet weather.

Concrete is environmentally friendly

► Concrete is completely recyclable.
► Concrete doesn't release odorous petroleum products into the air.
► Concrete conserves oil, which is used to produce asphalt pavements.
► Replacing asphalt pavements with concrete can help to lower summertime temperatures.
► Concrete reflects sunlight instead of absorbing it.
► The "heat island" effect seen in large cities has been attributed, in part, to the use of asphalt pavements.

Concrete is aesthetically pleasing

► Concrete pavements have a clean appearance and brighten neighborhoods, both day and night!
► Concrete can be colored and textured to produce attractive designs and patterns

So, there is no reason at all to lay tarmac, because concrete has the upper hand in every area.

But then in the interests of fairness I looked up a tarmac industry's site.

Why Asphalt?

There are many reasons that highway engineers and motorists prefer asphalt. Simply stated, asphalt pavements are designed and built to last. Most roads are constructed in layers, with each layer playing its part in delivering the best infrastructure possible. When it’s all put together, asphalt pavements can handle the toughest traffic punishment. Perpetual Pavements An asphalt Perpetual Pavement is designed and built to ensure that the structure lasts virtually indefinitely. Routine maintenance is simply a matter of periodically milling (about every 12 to 20 years) the surface for recycling, followed by placement of a new, smooth new overlay. Not surprisingly, these periodic overlays significantly improve the ride quality and fuel consumption of vehicles traveling these roads. Bottom line: Throughout its life, an asphalt pavement’s ride and performance are just as good as new. Smoothness Studies have demonstrated the fact that pavement smoothness is a significant determinant of vehicle fuel economy. The smoother the pavement, the lower a vehicle’s fuel consumption. But which tends to be smoother, asphalt or concrete? Well, one indication comes from state DOTs’ standards, which have specifications for newly built roads. If the road does not meet the standard, the contractor’s pay is reduced. Some states have different standards for asphalt and concrete, and in every state where this is the case, the requirements for asphalt roads are more stringent than for concrete roads. Smoother pavements also last longer because trucks’ tires roll more easily along the pavement instead of bouncing on bumps – and such bouncing actually accelerates road deterioration. Studies show that improving pavement smoothness by 25 percent results in almost a 10 percent increase in pavement longevity. Smooth roads don’t just save taxpayers money by lasting longer, they also conserve precious natural resources. Quiet pavements Noise, including road noise, is a pervasive form of environmental pollution. There is no better way to reduce road noise than to treat the problem at its source. By paving roads and highways with asphalt, the noise generated by at the tire-pavement interface – noise that affects people as they go about their daily lives – can be significantly reduced. Paving with asphalt is actually more effective than building expensive, unsightly noise walls. Speed of construction Paving with asphalt cuts construction project time significantly and eliminates the long curing times of concrete. As a result, traffic flows more smoothly and impact on commerce is minimized. Asphalt paving projects can be planned and carried out to take advantage of off-peak periods, like nights and weekends. Asphalt is ready for traffic right after it is compacted and cooled, meaning that roads don’t have to remain closed for curing. This enhances traffic flow and minimizes closures and delays that frustrate motorists and cost money. Maintenance is quick, cost-effective, and less disruptive than with concrete pavements. Versatility Asphalt is best for parking lots, and for such specialized applications as airports and racetracks. Parking lots Asphalt is an economical, environmentally friendly, fast-to-construct material for parking lots. About 85 percent of the parking lots in the U.S. are asphalt. Airports Busy commercial airports such as Baltimore-Washington International, Oakland International, San Francisco International, McCarran (Las Vegas), Pearson International (Toronto), and Logan International (Boston) have main runways surfaced with asphalt. Boston Logan's airport has paved a runway with warm-mix asphalt, making it one of the greenest airports in the world. Asphalt is also used on 85 percent of the runways at general aviation airports. Asphalt's speed of construction makes it an ideal choice for rehabilitation of busy aviation facilities. Race tracks Asphalt pavements provide smooth driving surfaces combined with the excellent traction demanded by professional stock car racing. Of the 33 NASCAR race tracks across the country, 31 are paved with asphalt. Of the 88 race tracks listed for the NASCAR Short Track series, 64 are asphalt, 21 are dirt or clay, and only three are concrete.

 

Of course, tarmac trounces concrete on every parameter. You'd be mad to lay a concrete road.

Which leaves us all a little bit more knowledgeable, but none the wiser!

Which I thought was all rather amusing. But then I'm like that.

I also prefer tarmac.