Wednesday, March 14, 2012



The myth of the traffic growth even when it crashes remains a staple mantra of planners and engineers—remember the Circumferential Highway anyone? Burlington (VT) perpetuates the myth in its downtown planning process, PlanBTV. A key base PlanBTV report claims--without providing evidence--that vehicle travel will increase one percent a year for the foreseeable future.

Now a couple of decades ago—the 1980s—found Vermont and New England vehicle travel growth up over 30 percent—but after the 1980s the sharp downtrend started leading to a 3% growth in the first decade of this century with Rhode Island actually turning negative. New England car travel growth even trailed of population growth just over 3%.

Vermonters can reasonably expect vehicle miles of travel turning negative this decade for a number of reasons. Urban Vermont leads the downtrend with then Vermont Agency of Transportation (VAOT) providing a five-year “short term” traffic factor for urban areas for planning purposes—the factor for a decade has remained about 0% change for planning purposes.

Take a closer look at Burlington and you find, for example, that one of the three corridors feeding the downtown, Route 127, the “northern connector” hit its top numbers in 1989 and since then, over two decades, declined steadily averaging -1.1% a year with a daily volume of 14,300 last year, down 21.3% for the period 1989-2011 with both 2010 and 2010 in the negative. No growth here.

How about the southern gateway, Route 7? Route 7 shows minor growth or decline over two decades at the I 189 interchange. And, I 189 itself since 1992 has added a puny few cars annually, averaging an increase on a per decade basis 30 more cars on and 30 more cars off, 0.3% growth per year or a 3% per decade rate of increase. Most of the short road sections around the I 189 interchange on Route 7 peaked about two decades ago. No growth here.

Finally take a close look at three downtown street sections: (1) Main Street from St. Paul Street to Battery Street; (2) Battery South to King Street; and (3) Battery Street north to College Street. Any growth on these three segments? From a base of about 1990 to 2010—two decades—the Main Street section daily numbers dropped 34%, Battery from Main to King down 21%, and Battery Main to College 10%. Really, will the drop in car travel ever stop around here?

It is important to emphasize that even car travel downtrends mean some roads will increase while most decline. For example, several interstate segments which carry about a fifth of all highway traffic statewide do show some growth.

Roundabout Potential

In terms the actual numbers each of the intersections in the downtown—St. Paul/Main Streets, Battery/Main Streets, Battery/King Streets and Battery/College Streets—all have vehicle counts which suggest a single lane roundabout with its safety for walkers can be considered. Single lane roundabouts offer a 90% reduction in walker injuries and about the same benefit to car occupants. The roundabout holds the key to a highway “zero fatality” rate policy which is advocated by AAA since no other technology can reduce speeds along typical streets and highways as well as radically improving safety at intersections. And single lane roundabouts even in the eventuality of increased traffic generally outdo the performance of what really is obsolete technology, traffic signalization.

So when the planners and engineers talk about increased car travel numbers, ask them to provide the data and reasoning that supports their claims.

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