The trend line for the transportation sector is less encouraging. Transportation emissions have begun rising as the economy rebounds. John DeCicco at the University of Michigan Energy Institute, who wrote the study, attributes the rebound we’ve seen during the past four years to straightforward causes: economic recovery and more affordable fuel prices. Vehicle sales numbers have been rising for several years, in particular for trucks and SUVs, and people are traveling more miles.
The trends have significant implications for the country’s energy policy. President Barack Obama’s Clean Power Plan will help ensure that emissions from generating electricity continue to fall in the coming years, and there are plenty of alternatives to coal-fired power plants. As for transportation, gasoline and diesel figure to keep dominating the market for decades because electric cars, the alternative, have been slow to take off. Federal laws designed to increase fuel efficiency and reduce tailpipe emissions will only serve to offset increasing travel demand, DeCicco says.
Very accurate centimeter level GPS readings has been around for a few decades can be made with a scattering of auxiliary base stations and a fair amount of signal processing. Not cheap, but very useful. Now it has been demonstrated on the low end - perhaps practical enough for cars.