Sunday, February 12, 2012



No more tables showing car travel growth among New England states as Rhode Island notched a 0.9% decline 2000-2010 breaking a century old trend. And the other five New England states declining growth may join Rhode Island in negative territory this decade. Average overall growth for New England hit a puny 3.4% continuing a rapid descent towards below zero--38% growth in the 1980s and 16% in the 1990s. The car travel trend now in slow population growth areas like the northeast and midwest now points continuously down.

Car travel numbers hit another decades first for New England as 3.4% car travel growth trailed population increase for the six states for the decade, 3.7%. The leader of the sixpack of states, as almost always, New Hampshire, could only muster a car travel growth of 8.7% along with its leading 6.5% 2000-2010 population increase. The three largest population New England states recorded next lowest car growth numbers, Massachusetts 3.0%, Connecticut 1.7%, and Maine 2.5%. Data on 2010 became available from the Federal Highway Administration (FHWA) within the past month.

One asks why do car travel growth around the 0% mark make a difference? First note that while car travel plateaus and declines, numbers for public transit, Amtrak and walking and bicycling increase mostly in high single to low double digits. Second, those who dabble in programs and policies to contain car travel growth through incentives and alternative services routinely point that this approach—called demand management—can make about a 10% cut in car travel being addressed. Well, in New England, welcome to the age of demand management!

One example of demand management is the Chittenden County Transit Authority “link” service between Burlington and Montpelier (VT), distance of about 40 miles which takes about an hour by interstate. Demand for this service begun about 2000 has been so successful in drawing commuters there are eight trips a day in each direction including a noontime trip. Standing room only became a problem almost from the start of the service an still occurs from time to time. And, to assure one gets to bring a bike on the two-bike rack on each bus one must make sure to pick up the trip at the first stop. The Montpelier-Burlington service has easily drawn over 10% of city-to-city commuters who otherwise would face solo driving or carpooling. Next? Perhaps light density commuter rail between the two cities with some of the States' largest employer, a possibility outlined in three different studies of the potential dating from as early as 1989.

Estimating car travel growth (the technical description “annual vehicle miles of travel,” AVMT for short) is both a science and an art. A science since any vehicle travel in a state must be tied to fairly well known gasoline and diesel sales which because of state taxation are carefully collected and monitored by the taxation people. The mix of vehicles also rests on the solid base of vehicle registration data. The art comes in the estimation of cross state border travel—which in the case of Vermont has been estimated as high as 35% and obviously involves travel not wholly connected to instate gasoline sale, ditto for long distant truck haulers.

For Vermont—as well as the other three smaller states New Hampshire, Maine and Rhode Island—change of car travel inherently includes some error, the smaller the car travel the higher the possibility of a larger variation. Still, aggregating numbers at the New England level erases the bulk of any estimation error—and going from 38% in the 1980s to 3% this past decade areawide presents an irrefutable trend.

The Vermont number for the last decade also involves two substantial changes in estimating methodology and therefore remains somewhat suspect for the 2000-2010 comparison. As one whose experience with trends of car travel dating from working with data and evaluation in the NH Department of Transportation in the 1980s and the Vermont Agency of Transportation during the 1990s the sharp and historic decline vehicle travel was recognized from almost the beginning and an ongoing discussion topic with attention to carefully evaluating and monitoring the trend. The Vermont Department of Public Service early this decade estimation of car travel increase for 2010 was estimated about 8% in internal economic analysis.

My own prediction for the early 2000s car travel for a slow-growth New Hampshire County, Cheshire, whose population and growth more closely mirrored Vermont, a prediction contained in expert court testimony amounted to 6.9% per decade, an estimate which utilized population growth and a slight increase in driving age licensing percentage (1% per decade). My best guess for Vermont was 0% change 2000-2010 plus or minus 5%. At the time the 16% New England growth number was available in view of a Vermont study projecting 20% for the 90s (versus 17% actual) and a number in New Hampshire that Department was estimating in the same ballpark (22% actual for the 90s).

All the statewide data here comes from the FHWA “Highway Statistics” series which is easily accessed on line along with the states populations from the U.S. Census.

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