DIGEST 2006 - Sabita

Choosing road surfaces:
Bitumen, gravel and the fuel
price in South Africa
Don Ross
Professor, School of Economics
University of Cape Town
and University of Alabama
Four fifths of SA’s roads
(ex clud ing ac cess roads)
are un sur faced. While this
is not high by gen eral Af ri can
stan dards, it is more than we
find in coun tries with per
capita GDPs sim i lar to ours.
There are strong economic
reasons for thinking that many of
these roads should be upgraded to
a bituminous pavement, at least
among those made with gravel
rather than in situ soil. The same
reasons argue against building
new roads according to principles
that preserve the current ratio of
bitumen to gravel, or tip it further
in favour of gravel. Simply put, a
higher proportion of new roads we
lay down should be bitumensurfaced.
This remains true despite
significant increases in the price of
bitumen, driven by the general
spike in the cost of petroleum
products, since early 2005.
Certainly, these increases have
stressed road budgets. The
Gauteng Department of Public
Transport, Roads and Works
reported in 2005 that the cost of
upgrading a gravel road to a low
volume sealed road had increased
by 67% since 2004, and the cost
of upgrading to a standard
surfaced road had increased by
48% in the same period. This
obviously implies that fewer roads
can be upgraded or built from
scratch without increased budget
allocations, or until substantial
new efficiencies can somehow be
found.
Paved vs gravel roads
However, this obvious point should
not be confused, as it often is,
with the idea that construction and
maintenance of paved roads has
become significantly more
expensive relative to properly
maintained gravel roads. It is
often assumed that because
bitumen is a petroleum product, it
must inevitably become a
relatively worse option compared
to gravel and cement when the
world oil price is elevated.
This reasoning leads to the
conclusion that the proportion of
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