Beginning in 1970, they found, motorized passenger travel grew rapidly in all eight countries as greater prosperity led to rising car ownership and domestic air travel. But after 2000, when per capita GDP in the U.S. hit $37,000, passenger travel stopped growing here. In the other countries, passenger travel leveled out at a GDP of $25,000 to $30,000 per capita.“A major factor behind increasing energy use and carbon dioxide emissions since the 1970s has ceased its rise, at least for the time being,” Schipper said. “If it is a truly permanent change, then future projections of carbon dioxide emissions and fuel demand should be scaled back.”The peak travel study runs counter to government models predicting steady growth in travel demand well beyond 2030. Schipper and Millard-Ball say that their own findings are “suggestive rather than conclusive.” They speculate that highway gridlock, parking problems, high prices at the gas pump and an aging population that doesn’t commute may be contributing to peak travel. People already spend an average 1.1 hours per day traveling from one place to another, and driving speeds can’t get much faster.“You can’t pronounce one single factor for the slowdown in travel,” Schipper said. “The most important thing will be to see what happens as the economy recovers. Everybody expects oil prices to go up. But with new fuel economy standards, more hybrids and higher oil prices competing against a recovery in which people buy old-fashioned gas-guzzlers, the question is, what is going to win?”Most of the eight countries in the study have experienced declines in miles traveled by car per capita in recent years. The U.S. appears to have peaked at an annual 8,100 miles by car per capita, and Japan is holding steady at 2,500 miles.There are signs of saturation in vehicle ownership, too, at about 700 cars per 1,000 people in the U.S. — more cars than licensed drivers — and about 500 cars per 1,000 people in Japan and most of the European countries. Car ownership has declined in the U.S. since 2007 because of the recession.“You get to a point where everybody who could possibly drive, drives,” Schipper said.
If the travel market itself is actually saturated, this suggests that predictions of high amounts of induced demand for rail travel may not actually be borne out and that any gains in rail ridership will be at the expense of motor and air travel. On the other hand, if the saturation is due to problems with the currently available methods of air and motor, then induced demand may be a major contributor along with high levels of modal switch.