Evans, 'Roman Bridges', Bryn Mawr Classical Review 9410
URL = http://hegel.lib.ncsu.edu/stacks/serials/bmcr/bmcr-9410-evans-roman
@@@@94.10.23, O'Connor, Roman Bridges
Colin O'Connor, Roman Bridges. Cambridge: Cambridge
University Press, 1993. xvii, 235 pp. $100.00. ISBN
0-521-39326-4.
O'Connor, a professor emeritus of civil engineering and expert
in bridge construction, sets out to assess the Romans'
achievement as "the world's first major bridge builders" (p. 1).
The result is a highly informative book, not inexpensive, but
very attractively produced by Cambridge, and amply illustrated by
photographs and sketches, most of them the author's own.
Although O'Connor's book does not replace Piero Gazzola's
definitive study of Roman bridges (Ponti Romani,
Florence, 1963), on which it relies heavily, it does make
important contributions of its own to our understanding of how
Roman bridges were built and why they stayed up (or failed to do
so) when completed.
O'Connor organizes his study geographically (in contrast to
the chronological organization followed by Gazzola) and therefore
begins with an overview of the Roman road system, which
determined the location of the bridges themselves: "Bridges and
roads go together, for it is the roads which require the bridges,
and the bridges make possible the roads (p. 4)." His survey of
the Roman road system is in good part derivative, based on the
work of Chevallier and Sitwell, but this opening chapter provides
a convenient geographical framework for the bridges to be
discussed later and makes this book much easier to consult on
particular bridges than Gazzola's. In addition, his plates and
diagrams are much larger and more readable than those in Gazzola.
Chapters on Roman builders, technology, and building materials
introduce the heart of the book, a survey of masonry bridges
throughout the Roman world. O'Connor's presentation of
individual bridges is based in large part on that of Gazzola, but
he has obviously visited and studied a good many of the monuments
he describes, and several times he is able to correct figures and
statistics given in Gazzola's study (pp. 81, 100, 101, 109, 117).
The most interesting section of the book treats a subject not
fully addressed by Gazzola, the Romans' use of timber bridges.
These structures, O'Connor argues, were especially common in
Roman Britain but were built extensively throughout the Roman
world, frequently preceding later masonry constructions: "stone
bridges were likely to be second- or third-generation structures,
built to replace earlier crossings, constructed in a stable
environment, with access to adequate and known resources and a
developed infrastructure (p. 132)." Using Caesar's famous
account of his bridge across the Rhine (BG 4.17), he
presents a plausible reconstruction of the bridge and the
engineering problems Caesar faced in completing the span in ten
days. Even more fascinating is his detailed discussion of
Trajan's bridge across the Danube, designed by Apollodorus of
Damascus and depicted on well known reliefs of Trajan's column;
O'Connor argues that Apollodorus used twenty-one segmented timber
arches to span the river and create longest bridge ever built by
the Romans.
The only disappointing chapter is O'Connor's discussion of
Roman aqueduct bridges. He acknowledges that he was not able to
consult Trevor Hodge's Roman Aqueducts and
Water Supply (London, 1992) while he was writing
his book and therefore describes his listing of aqueduct bridges
as "fortuitous and incomplete" (p. 150); unfortunately we must
agree. O'Connor's discussion of Rome's aqueduct bridges, based
largely on Ashby and Van Deman, omits completely the Aqua Appia,
Anio Vetus, and Aqua Traiana. The Traiana, of course, has large
sections above ground, some of which were later reworked by Paul
V for his papal aqueduct in the sixteenth century. The Appia and
Anio Vetus were largely underground conduits, but both are
certainly worth a mention in any survey of Roman bridges. The
Appia, according to Frontinus (Aq. 5.5) crossed the valley
of the Porta Capena on an arcade of 60 passus). If this
were a masonry bridge from the time of the line's introduction
(312 B.C.), it might well have been the oldest continuous arcade
in Roman architecture; if A. W. Van Deman [RE 8A (1955)
468] is correct, however, the arcuatura cited by Frontinus
may have been part of a second-century restoration of the Appia,
replacing an earlier fourth-century timber structure. In any
case, the Aqua Appia bridge at the Porta Capena merits
discussion. Even more surprising is O'Connor's omission of the
Hadrianic "Ponte della Mola" of the Aqua Anio Vetus, one of the
most interesting examples of imperial upgrading of the republic
lines and a fascinating bridge in itself, as well as Nero's
Arcus Caelimontani and the Domitianic bridge in the
Valle S. Gregorio which carried this branch line of the Aqua
Claudia to the Palatine Hill, the reconstruction of which remains
controversial. O'Connor's discussion of aqueduct bridges in
Spain and Gaul is better, since he had access to the studies of
Casado (Madrid, 1972) and Grenier (Paris, 1935), but this one
adds very little that is new and might well have been omitted
altogether.
Much better are his two final chapters on the design and
construction of Roman arches and modern analysis of Roman arch
design. Both treat highly technical subjects, which will no
doubt be of more interest to engineers than to classicists, but
O'Connor's discussion of loads, reactions, pier thicknesses, and
falsework construction is highly illuminating, indeed the place
to which I will send all future students who are interested in
such problems. Both chapters include very clear diagrams and
graphs. The book also contains a glossary of technical terms and
appendices listing 330 masonry bridges, all organized
geographically, 34 timber bridges, and 94 aqueduct lines, as well
as a list of works cited.
O'Connor is a civil engineer, not an ancient historian or
classicist. His background therefore contributes directly to the
strengths of this book: we have here a thoughtful examination of
Roman bridge building by a professional who is well aware of the
problems of engineering and construction techniques. The best
parts of the book are therefore those directly focussed on such
topics as the statics of arch design, why the Narni bridge
collapsed, or Apollodorus' bridge over the Danube. There are,
however, many errors of historical detail in O'Connor's text
which the readers for Cambridge should have caught: to give some
examples, the third king of Rome was Ancus Marcius, not Martius
(pp. 2, 7, 142), the First Triumvirate is not to be dated to 59
B.C. (p. 16), the heir to Julius Caesar was Octavian, not
Octavius (p.36), and Clemens Herschel did not discover a
manuscript of Frontinus in 1897 (p. 37).
In addition, there are some startling omissions in the
extensive bibliography. O'Connor briefly discusses the religious
significance of bridges (pp. 2-3) but curiously does not cite
Louise Adams Holland, Janus and the
Bridge (Rome, 1961), a source which should have also
appeared in his treatment of the Pons Sublicius (pp. 141-42).
His presentation of Marcus Agrippa as a bridge builder appears to
be entirely based on F. A. Wright's biography of more than fifty
years ago (Marcus Agrippa: Organizer
of Victory, London, 1937) and ignores J-M. Roddaz's
much more recent and comprehensive study (BEFAR 253, Rome,
1984). The chapter on aqueduct bridges relies much too heavily
on outdated sources like F. W. Robins, The Story
of Water Supply (Oxford, 1946), and one
surprising omission in his discussion of timber bridges is
Russell Meiggs, Trees and Timber in
the Ancient Mediterranean World
(Oxford, 1982).
These disappointments aside, O'Connor has given classicists a
fresh look from an engineer's perspective at the Roman
achievement in bridge building. As his concluding chapter
states, Roman bridges are impressive not only for the number of
them documented or the extent to which they were built throughout
the Roman world, but also for the technology involved: arched
bridges required skills in site location and layout, choice of
construction materials, employment of lifting devices, the
fastening of falsework and other supports, and use of proper
tools and equipment. His book ably demonstrates how the Romans
combined all these skills to produce "one of the most successful,
extensive and lasting of all human, material achievements" (p.
188). This volume will not replace Gazzola's monumental
Ponti Romani, but it does present to its readers a
comprehensive and much more usable account of bridges and bridge
building in the Roman world. Order it for the library, because
you and your students will be consulting it sooner or later, and
more than once.
Harry B. Evans
Fordham University