JRscooby wrote:
valhalla360 wrote:
Actually, mandates haven't had a lot of impact. Most of the big jumps in efficiency happened when fuel prices spiked and the customers chose to buy higher MPG vehicles. Mandates without a fuel price spike have typically resulted in circumvention of the rules...Example: the proliferation of the mighty SUV "truck" that is for all practical purposes just a station wagon rebranded.
Mandates don't make a difference? Then why do auto companies fight so hard against them?
Now mandates don't always work as planed. When smog started to get bad, Cali started, other states then Feds followed with mandates to clean things up. (Remember the "road draft tube"? When I saw a explanation of PCV, I put that system on my '54 GMC I6 running in my '58 Chevy Engine bay much easier to keep clean) But when mandate said must clean what came out tailpipe, the technology was either not available or too expensive, so MPG went way down. (Personal example; My wife, in 327 small block powered '67 Nova would get about 16-17 MPG driving to/from work. Replaced with new '73 350 small block, 8 MPG. At same time my '72 half ton, 350 small block ran 16.) And like you say manufactures/buyers changed vehicles offered. Before the station wagon/SUV thing, pickups changed into sedans without deck lids on the trunk. But when high gas price/competition from foreign and more efficient cars caused advances in engine efficiency on smaller models the "fleet average" mandate forced that tech to spread up the line.
Working in the industry, recycled asphalt is very limited on roadway projects and that's where the vast majority is used. The problem is as the asphalt ages, it "dries out" and becomes less effective as a binder in the asphalt concrete. When it's used, it's typically more for political reasons as opposed to engineering and capped at 5-10%, so as not to impact the quality of the pavement too much. Reducing the amount of virgin asphalt used by 50% but having to repave twice as often, doesn't provide much benefit. Ground up it does make a nice gravel for driveways.
Fact is asphalt has never been a great road surface. If dumped in a fill, tests have shown the oil will leach out, contaminate water. And even if the road is unused the surface will break down, allow water into subgrade.
Over the last couple of decades, in this area, recycling concrete has increased. In the past, a early step in repairing a interstate highway bridge was asphalt crossovers to get traffic off bridge. Now they are using concrete.
About that "nice gravel for driveways". 1 summer I worked my truck and trailer for months, loading millings where suburbs where repaving, hauling into small towns, stopping at the grain elevator to weigh, then tailgating out on the oiled dirt/chipped roads. Little work with skid-steer, blade, and roller, call the streets "improved"
a) The manufacturers fight mandates because it takes time, money and effort to circumvent them to give customers what they really want and will pay good money to buy. They really don't care what they produce as long as it sells and makes a good profit. Plus more often than not, you run into the law of unintended consequences when you apply politically based mandates.
Fuel price on the other hand correlates nicely with MPG increases.
- From the mid70's to mid80's fuel prices spiked. Over the same period the fleetwide average (cars & trucks) went from 14 to 22mpg.
- From the mid80's to the mid00's, fuel prices were back down and held pretty much steady when adjusted for inflation. Fleetwide average actually lost ground to around 20mpg.
- From the mid00's to the mid10's, fuel prices again spiked (inflation adjusted) and fleetwide average went up to just shy of 25mpg.
If you want to improve MPG, increase the price of fuel and there is no need for ineffective mandates. Customers will demand it and manufacturers will provide it.
b) So if Asphalt is such a horrible material, why is it that around 80% of paved road miles are asphalt. Keep in mind Portland Cement Concrete requires burning a lot of fuel to make the cement...leaving behind more asphalt cement from the left overs of a barrel of crude oil to let's not pretend it's a "greener" alternative.
Can you source these tests that show oil leaches out from asphalt? Cars leaking oil onto the pavement can do that but particularly for old asphalt concrete, the vast majority of light oils that would be subject to leaching out are long gone. That's the biggest problem with old asphalt...all that remains after 30yrs are the solids, so it doesn't make a very effective binder.
I do a lot of Maintenance of Traffic Plans. I can't recall ever seeing a Portland Cement Concrete temporary crossover used. Not saying it's never been done but if you came across it, it's very much an outlier.
15-20yrs ago, there was a lot of effort into recycling asphalt concrete and yes, it does get used in small quantities today but mostly as a checkmark of how the project is "green". Usually they wind up using a softer grade of asphalt with more light oils (subject to evaporating into the atmosphere or leaching into the soil) that would otherwise be refined out for other uses to compensate for the low quality of the 30yr old material.
The other problem is you have far less control over the quality of the aggregate (sand & gravel). With asphalt concrete, the aggregate is typically more important than the binder.
So no asphalt is a perfectly good material and it isn't going anywhere as there is no viable alternative for paved roads in the quantities required.