Commuters in the United States are collectively incurring billions of dollars in extra costs as a result of sprawling nature of the country’s leading urban centres.

A study produced by Daniel Hertz of City Observatory has employed an innovative method to more accurately quantify the hidden costs created by urban sprawl as a result of extended commute times.

The index developed by Hertz found that commuters situated in the 50 largest metro areas in the United States collectively spend roughly 3.9 billion extra hours travelling to and from the workplace each year as result of urban sprawl, the equivalent to 50 hours per individual worker.

This wasted time on roads or public transit translates into more than $107 billion per annum, or $1,400 per commuter.

Hertz produced this figure by using data from the Brooking Institution to compare average commute lengths for America's 50 largest cities to the hypothetical commute lengths for those same cities were they more compact in structure.

Hertz divided the cities on the list into the two categories of those with populations beneath 2.5 million and those with larger populations, and used the shortest average commute length for each category minus no more than 0.5 miles as their respective benchmarks that could be achieved by more compact urban design.

These two figures turned out to be six miles for cities with populations under 2.5 million, and 7.5 miles for more populous urban centres.

In order to determine the "sprawl tax" incurred by each commuter travelling making the round-trip to work each day in a given city, Hertz simply multiplied the difference between the actual average commute length and the benchmark commute length by the estimated cost-per-mile figure for a mid-sized sedan.

This figure could there used to determine the sprawl tax for a given area, as well as the sprawl costs for all commuters in America's 50 largest cities.

Hertz's has certainly employed a broad strokes analysis to achieve a rough estimates of the time and monetary costs of urban sprawl, using only two population categories as well as focusing on commute lengths alone to the exclusion of other factors such as pollution, health impacts, as well as traffic accidents.

His analysis nonetheless goes a long way towards giving urban planners as well as members of the general public a more vivid sense of the economic costs incurred by the expansive sprawl of large cities.

Similar approaches could be highly relevant to Australia, given the marked affinities between American cities and our own, as well as similar development conditions where the size of the national land mass gives scope for urban centres to expand unchecked.

Dulux Exsulite Architecture – 300 X 250 (expire Dec 31 2016)