Decoding Transportation Policy & Practice # 2
Posted 4/30/02
The
Nation’s Road Capacity:
How Fast is it Growing?
Proponents of highway
capacity expansion often claim that road building is lagging far
behind. The statistic
they use to support this argument is that lane miles of
roadways have grown by only two percent since 1990. But once we ‘decode’ this
figure, it is clear that this is an inaccurate way to assess
the capacity of our surface transportation
infrastructure.
From 1990 to 2000, lane miles of all roadways in
the United States grew by slightly less than 2 (1.8) percent. The number is
startlingly small, especially given the large increases in funding
made available for surface transportation through the federal
transportation laws ISTEA and TEA-21. How could this be? It turns out that the figure
greatly misrepresents the capacity of the nation’s roadway
system. A closer look
at the numbers from the Federal Highway Administration (FHWA)
reveals why.
Where the Roads
Are
Though most of the population lives in built-up
areas and most driving occurs in these same areas, the vast
majority of roads are in rural areas. According to the latest
numbers from the FHWA, nearly 77 percent of the 8,223,393
lane miles of roads in the U.S. were located in rural areas in
2000. While the United
States has a rural history, for the last century most of the
population has lived in cities, suburbs, and towns. Statistics from the Federal
Highway Administration show that in 2000 more than 72 percent of the
population lived in ‘urban’ areas (defined as central cities, towns,
or urban clusters with a population of greater than 5,000
people and areas contiguous to that central place). More importantly, most (61
percent) of the miles driven in the U.S. are on urban
roads. (see table, next
page)
Where Capacity Is Growing
As completion of the
Interstate system neared, investment in new roadway capacity to
serve built-up areas where the majority of people live and drive has
increased. So that
while roadway capacity in rural areas has not grown, roadway
capacity in metro areas
has grown markedly, averaging more than 22,000 additional
lane miles each year during the last decade. New numbers from FHWA
show that lane miles of roadway in urban areas grew by more than 13
percent from 1990 to 2000. While some of the
growth of the urban road network was due to re-classification,
new roads and widenings accounted for 69 percent of the total
growth.
Because there are so many
more miles of roadway in rural areas, this significant investment
does little to move the total road mileage for the entire
country. As a result,
the national figure of 2 percent road growth has little
relevance in a discussion of needed capacity.
Finally, it must be noted
that rural roads, even with no capacity increase in recent years,
are still far from carrying the volumes of traffic they were
designed to. On a
mile-per-mile basis, rural roads carry only 20 percent as much
traffic as urban roads.
Even if the number of miles driven on rural roads grew 250
percent, rural roads would carry only half as much traffic on a
per-mile basis as urban roads.
Transportation planners have not built new roads in rural
areas because there is generally no need to increase
capacity.
But Why Are Our Roads So
Congested?
This discussion begs the
question, given that roadway mileage in urban areas has been growing
significantly, why does
traffic congestion seem to be so much worse? It has more to do with our
growing reliance on driving for daily tasks. For more on this,
see Easing the Burden or Why Are the Roads So
Congested? on STPP’s website at www.transact.org.