AN ENDEAVOUR TO IDENTIFY ROMAN BRIDGES
BUILT IN FORMER HISPANIA
Published in the Actsbook of the first
International Congress on Construction History
Instituto Juan de Herrera, E.T.S. de Arquitectura de Madrid
Madrid, 20-24 january 2003
TRAIANVS © 2004
Over the course of history, bridges have enjoyed wide social acclaim as
proven by the numerous references to them in popular tradition and in historical
documents. This has not been reflected in the field of surveys however, where
the number of books devoted to the subject is quite low in comparison with that
of those centred on architectural works. The first specific study of bridges was
written in 1716 by Henri Gautier. The fact is that historians have shown little
interest in ancient public works and engineers have not paid too much attention
to them either.
Following the establishment of new policies of preservation and appraisal
developed in Europe in the second half of the twentieth century, when the notion
of heritage transcends architectural monuments, this tendency would change and
the historical and heritage value of many technical constructions (former
industrial installations and historical public works in general) began to be
acknowledged as new categories of cultural heritage were defined. Within this
new context, in recent decades a number of studies have appeared on ancient
bridges which, in general terms, describe the works in question and provide
historical documents yet without analysing in any great depth the stonework, an
essential factor in the investigation of their constructional history, above all
in the cases of the oldest bridges, on which scant documentation is available.
Our study will focus precisely on this feature, and will attempt to furnish a
systematic analysis of the formal and constructional characteristics of Roman
bridges in Hispania, applying a method of work that has enabled us to
reach a series of conclusions which will prove vital in the identification.
Methodology
Over the last few years a certain methodology has been developed to further
the identification of the Roman bridges in Hispania, based on the
analysis of the stonework of surviving bridges (Durán 1996; Durán 2001).
Initially the idea was to gather the maximum amount of information published on
the bridges in question, all of them of unquestionable Roman origin, and to
obtain as much data as possible by means of precise topographical upliftings of
them all. Varying historical and territorial determinants were taken into
account, as was their transformation over the course of time, while other geo-technical,
structural and hydraulic factors were also analysed. The resulting data has
enabled us to systematise these works, and obtain a set of constructional and
formal features that will prove extremely useful in ensuring accurate
identification.
It is difficult to date these bridges with precision due to their formal and
constructional likeness over various centuries, which has led us to restrict our
object exclusively to identifying them. This limitation will no doubt be
overcome in future thanks to the undertaking of new historical, archaeological
and constructional studies in the sphere of the former Roman Empire.
Analysis of Hispanic Roman Bridges
Bridge building throughout the Roman Empire was carried out by technically
skilled specialised workers in the military, whose work was no doubt subject to
precise rules. The stonework, a paradigm of fine construction, was executed in a
solid stable fashion to ensure its eternity, as described by Caius Iulius Lacer,
the architect from Alcántara who erected his work for it to last "forever, over
the centuries of the world".
Standardising the intrinsic features of such constructional rigour will
enable us to identify the possible Roman origin of ancient bridges. Yet scholars
have not always proceeded in this way, and have occasionally identified bridges
as Roman when these presented stone vaults of an indefinite date, or merely
influenced by the popular term used in reference to them. In our opinion the
adjective 'Roman' should not be applied indiscriminately to any bridge that
happens to exist where a former Roman bridge once stood, but exclusively to
those bridges that have preserved their original stonework almost entirely, or
else those that, while only preserving a part of this, are still distinguishable
as Roman despite subsequent reconstructions. The Sommieres bridge in the French
region of Provence for instance, can be considered Roman in spite of its
successive reconstructions, for it preserves the shape and many of the specific
features of Roman works. On the contrary, Ponte Vella in Ourense cannot be
regarded Roman despite having preserved a part of its original work, because
Mediaeval and modern reconstructions have completely altered its primeval form.
In cases that do not fall neatly into either category, we have opted for the
expression "bridge in the Roman tradition" describing works which, in addition
to possessing certain historical conditions, present other constructional
features that enable us to presume the previous existence of a Roman bridge in
the same spot.
The task of identification proves easier in the case of ashlar masonry, as
the scabble, the bond and the painstaking execution are the first clearly
recognisable signs. In the case of ashlar (opus vittatum), schistose,
brick (opus latericiae) or a combination of these materials, the
difficulty increases, for such works are barely distinguishable from others made
at a later date. No bridge made of masonry or of flagstones has been identified
in former Hispania, and only one built of bricks has been officially
recognised. A schistose bridge quoted as Roman is the one on the outskirts of
former Asturica Augusta (Astorga), on the French road to Santiago.
At present somewhat covered by earth, it presents segmented arches measuring
3.60 m wide and its roadway has a slight double slope. Having analysed the work
in some depth, one reaches the conclusion that none of its features allow it to
be identified as Roman, an assumption reinforced by the fact that it stands
outside the route uniting Astorga and León.
Identifying brick bridges is not an easy task either, as this material has
remained practically unaltered over many centuries. Only the size,
constructional layout and comparison of such works with other Roman examples
allow positive identification. The Mérida sewer (Alcantarilla de Mérida), the
only work classified as Roman, was built on the former road between Emerita
Augusta and Bracara Augusta, according to a plan drawn up by
the master builder Fernando Rodríguez in 1796 (González Tascón 2002, 143). The
size of brick used in this bridge was 29.6 x 44.4 x 5.5 cm, laid out in radial
stretcher and header courses, exactly the same as the Roman bridge in Saint
Albans,
England (Harney 1990, 45). The
stonework in another example, the Roman bridge in Carmona, however, presents no
specific feature betraying such an origin, despite standing in the place where a
wider bridge had existed previously, according to remains preserved on both
abutments and a layout resembling arcading. Yet the Roman bridge over the river
Odiel, in the vicinity of Aracena, standing on the Urion-Arucci road
(Ruiz Acevedo 1998, 84-85) did perhaps preserve a Roman arch, the one with the
smaller span, presenting the same constructional characteristics as the
Alcantarilla de Mérida.
Of the thirty-two bridges in Hispania (Spain and Portugal) examined in
this study, only one preserves very few remains (Aljucén bridge in Cáceres),
while six others preserve quite a significant proportion of original stonework
and have suffered a number of reconstructions (Ponte Vella, Ponte Cigarrosa,
Ponte Navea and Ponte de Baños de Molgas in Ourense, Ponte Romana in Lugo and
Bridge of the Devil in Martorell). Two are of dubious Roman origin yet have
traditionally been regarded as Roman (Villa del Río and Los Pedroches bridges in
Cordova), and the remaining twenty-three preserve much of their original
stonework (Durán 1996, 167-178). The studies carried out have allowed us to
determine nine characteristics or constructional features taken as the basis of
the identification process.
Formal and Constructional Singularities of Hispanic Bridges
The uniformity of Roman construction in time and space is quite obvious in
bridges, as the singularities observed in those built in Hispania appear
in other works built in other regions of the empire, a fact that enables us to
suggest, having defined their peculiarities, that all works that present them,
totally or partially, are quite likely to be of Roman origin. None of these
features, widely present in Roman works, proves this fact in itself, and must be
accompanied by further evidence of a historical or archaeological nature, for
many such traits have been used in bridges built at later dates.
1. Bridge Width
One of the most interesting features of these works is their width. Most of
the bridges built in Hispania and in other parts of the Roman Empire are
over five metres wide, a significant dimension compared with bridges built later,
especially in the Middle Ages, which were seldom so wide. Perhaps this was
because Roman builders preferred not to reduce the breadth of the roads (usually
six or seven metres wide) on their course over the bridges.
Our study has centred on 146 different widths, many of them measured for this
purpose and the others taken from Galliazo's survey (Galliazo 1996). The results
obtained show that only 18.5% of the bridges measured less than five metres wide,
in other words, 81.5% exceeded this value, while only 5% of bridges had a width
of less than four metres. As an example, we present the widths of bridges in
Roman Gallaecia (Galicia and
northern
Portugal):
-Between 4.50 and 5.00 m - A Pontóriga bridge (4.50 m), Sao Lourenço sewer
and Ponte Freixo (4.60 m)
-Between 5.00 and 6.00 m - Ponte de Lugo (5.00 m), Ponte Pedriña (5.74 m),
Ponte San Miguel (5.50 m) and Ponte da Ribeira o Forno (5.50 m)
-Between 6.00 and 6.50 m - Ponte de Pedra (6.00 m), Ponte de Chaves (6.10 m),
Ponte Cigarrosa and Ponte Vella de Ourense (6.15 m), Ponte Bibei and Ponte Navea
(6.30 m)
-Over 6.50 m - Ponte de Lima (7.10 m), Ponte do Arquinho (7.30 m).
2. The Horizontal or Slightly Inclined Grade Line
The platforms in 75% of the bridges studied have horizontal grade lines,
while the other 25% present a slight inclination with slopes of roughly 3%.
If we extend this analysis to bridges in other regions we notice that most
have similar characteristics, although those with horizontal grade lines are
dominant. Pont Julien, in the French department of Vaucluse, presents the
greatest inclination, yet even in this case the slopes are no higher than 9%.
3. Rustic Work
Rustic work appears in all the bridges in Hispania, and in most of
those preserved in other parts of the former Roman Empire. The taste for this
form of scabble was a Greek legacy that can be traced back to many military
constructions from the Hellenistic period onwards, with aprons made of rustic
work (Adam 1982). The reasons explaining its appearance could be both economical,
as rustic work avoided carving the totality of exposed face, and practical,
designed to protect the edges of the ashlars during their transport and laying
up. Subsequent use in Roman times obeyed aesthetic motives, for when the rustic
work was placed in the lower areas of constructions it granted them a sense of
robustness (Lugli 1957, vol. 1: 208), as we see in the bridge at Alconetar in
Cáceres and in the Bridge/Aqueduct of the Devil in Tarragona.
The most frequent form of rustic work in the masonry of bridges in
Hispania is rough-hewn exposed face, occasionally with chamfered edges and
in most cases with bands dressed with chisels or fine gradines on one or several
edges, forming anathyrosis (Lugli 1957, vol. 1: 207).
This feature is quite common in Roman constructions yet its mere presence in
ancient bridges does not guarantee this origin, as it has been employed over the
course of time and has even been copied in reconstructions dating from later
periods, thus producing confusion. Rustic work practically identical to the
original stonework was carried out by Portuguese stonemasons in the
reconstruction of two arches of the Segura bridge in 1571 for instance, such a
fine imitation that it is barely distinguishable (Durán 1996, 175).
4. Alternate Stretcher and Header Courses
The alternation of masonry units in stretchers and headers in the same course,
or the presence of alternate courses of units in stretchers and headers are
bonds that the Romans also copied from Greek construction, where they originally
appeared when structures built with logs of wood alternately placed crosswise to
grant them stability were subsequently reproduced in stonework. Of the two
dispositions, the latter (alternate courses of stretchers and headers) is the
most frequent in Roman construction, further proving its systematic nature, well
suited to the Roman concepts of planning, efficiency and speedy execution (Adam
1996, 119).
Bonds of alternate courses of stretchers and headers appeared in a number of
ancient works such as the Servian Wall in Rome, built between 378 and 352 BC,
the walls of Falerii Novi, built in 240 BC and the viaduct of Ponte Picchiao in
via Flaminia, built in 220 BC (Ballance 1951, 88). Defined by Lugli as a "Roman
system" (Lugli 1957, 175) due to the frequent appearance of opus cuadratum
in works, it was also employed in a fair number of bridges. Despite having been
considered a feature characterising construction before the age of Augustus, its
presence in works of an obviously later date invalidates this opinion (Ballance
1951, 95). This bond is usually found in the lower parts of abutments and piers,
designed to connect the stonework of these areas subject to greater thrusts and
movements than the rest. In this position we find it in Ponte Freixo in Ourense,
where a uniform unit of masonry was employed, measuring 1 x 1 x 3 feet placed in
alternate courses of stretchers and headers. In fact it can be traced in 67% of
the thirty-two bridges in Hispania we have been analysing, usually
beneath the springing lines of the vaults in the inner parts of piers and
abutments and on the channelling walls.
5. Ashlars with Holes in Dovetail Shape
Roman construction adopted this way of connecting units of masonry by means
of leaden cramps or dowels, reproducing joinery. Other more simple forms of
linkage were also employed (Ginouvès and Martín 1985, vol. 1: 28), some of them
until recently, such as the U-shaped metal cramps identified in Ponte de Pedra,
Portugal. This sort of cramp is easy to
make by bending the two ends of a reinforcing bar, and equally easy to put in
place, as it fits neatly into the two cavities that are then filled by tapping
lead to subject it.
As for the dovetail mark, we must say we find it an extremely interesting
feature that does not appear in works from later periods. Some authors hold the
opinion that this way of connecting stonework died out during the first century
AD (Adam 1996, 57), at the height of the Roman era. In our view this was not the
case in the construction of Hispanic bridges, for this trait appears in later
works such as Ponte Freixo.
This sort of linkage was placed in those areas of the work subject to
greatest external actions, areas susceptible of registering the most important
movements, usually the lower spans of abutments and piers, and the paving of the
foundation. We have only come across this form of cramp, joining voussoirs, in
one case outside of the region of Hispania, to be precise in the Chemtou
bridge in
Tunisia.
Few are the cramps that have survived, whether made of metal (usually
stemming from the Middle Ages) or of hard wood such as ash, holm oak or olive.
Two were sent by the engineer Alejandro Millán to the Real Academia de Historia
in 1859, discovered during the works of restoration of the Alcántara bridge in
Cáceres (Blanco 1977, 68), and others were found, reduced to ashes, at Ponte
Freixo during the works of consolidation carried out between 1989 and 1990
(Alvarado, Durán and Nárdiz 1989, 69). The scarcity of cramps was taken by G.
Boni as the basis of his assumption that the double dovetail did not obey any
constructional purpose but was merely reminiscent of the double-bladed axe, an
ancient religious symbol widespread throughout the Mediterranean basin (Lugli
1957, 237).
The double dovetail may be difficult to discern in some works, for it is
usually placed in the inner part of the stonework and can only be detected if
the work is incomplete or the units of masonry are removed from their original
positions. The existence of the typical extraction holes and, if visible, the
paving of the foundation also enable us to identify this sort of linkage.
The double dovetail appears in five of the thirty-two Roman bridges in
Hispania, namely, in the cutwaters of Ponte Freixo, in the channelling walls
and the right abutment of Ponte Navea and in the paving of the foundation of the
piers in Ponte Cigarrosa and the Segura and Villa del Río bridges. More recently
we have also come across it in the foundation and the supporting walls in the
Pertusa bridge in Huesca, an example not included among the thirty-two we have
focused on.
6. Uniformity in the Thickness of Vaults
This constructional feature must be clarified, as the uniformity we are
broaching should not be understood in absolute terms. Given that practically no
bridge has a constant vault thickness throughout its directrix, we have decided
to consider uniform only the threads whose variations in height do not exceed
10%. The thickness studied is that of the rib, the only thickness clearly
visible in most bridges, as that of the inner areas is only seldom perceptible.
The degree of thickness is more noticeable comparing the vaults of Roman
bridges with those on Mediaeval examples, for the latter present voussoirs of
more irregular sizes. Some Roman works occasionally evince a lack of uniformity,
but this is generally confined to a gradual variation of the height of the
voussoirs, from the keystone to the supports, or else to the existence of
voussoirs of exceptional size in the springing lines, in the haunches or in the
very keystones.
To the relative uniformity of the exterior threads present in 95% of the
Roman bridges we have studied, we must add the fact that the works that have
enabled us to observe the complete extrados of a vault (Ponte Freixo, Ponte do
Arquinho, Alconetar bridge, Ponte de Lima, Ponte San Miguel, Ponte Ribeira do
Forno and the aforementioned Pertusa bridge) thickness is constant throughout
the width. This is probably true in most Roman bridges, save in exceptional
cases such as the ribbed vaults of the Augustus bridge in Narni, Italy, and the
vault made of cement and stone rings in the San Martín bridge in Aosta. In
Mediaeval bridges however, it is quite frequent to find arrises or ribs that are
thicker than the central areas.
7. Careful Execution of the Bond and Joints of Masonry Units
This feature is also held in higher esteem as opposed to the neglect evident
in Mediaeval stonework, as the bonding and quality of the scabble in Roman
masonry stands out compared with stonework of later periods. In our opinion, the
refinement of the joints and the precise fitting of the ashlars distinguish
Roman works and are useful tools in the task of identification.
8. Manipulation Holes in Masonry
In this section we shall study the holes for hoisting the units of masonry
with gripping-tools, and those made on the upper or lower edges of the ashlars
to facilitate their positioning with levers.
The small holes appearing more or less in the centre of the ashlars and
voussoirs were made to hold the teeth of the metallic gripping-tools (ferrei
forfices) used in hoisting pieces (Adam 1996, 52). They are frequent in
Roman constructions and, of course, in numerous bridges, and their most common
shapes are triangular, circular and rectangular. Due to the fact that these
holes was not exclusive to this period - the use of gripping-tools similar to
ferrei forfices is still a widespread practice today - their presence
in ancient bridges does not necessarily prove a Roman origin. In spite of this,
and given that they appear in 67% of the bridges we have been analysing, we
consider them sufficiently meaningful to deserve inclusion in this set of
features.
The flattening practiced on the edges of the units of masonry to facilitate
their placing in position with levers can be observed in a number of bridges in
Hispania, such as Ponte Freixo and Ponte Bibel, yet never in later works.
This characteristic is typical of Roman constructions and its presence in
ancient works can be taken as sufficient evidence of Roman origin.
9. Dimensions in Roman Units of Longitude
The results of the transformation of the most significant dimensions of an
ancient bridge into Roman units must be regarded with some reserve, especially
if it is employed as the sole procedure to justify their Roman origin. The first
problem appears when it is impossible to obtain accurate knowledge of the
original dimensions. This is the case when the origin of the measurements is
unclear, as for instance in constructions with rustic work on the joints or on
the external face of the stonework (the difference between these two
measurements may be of up to fifteen or twenty centimetres). It also occurs when
it is likely that the measurements have suffered modifications due to a variety
of reasons, as a result of which the bridge will be affected throughout its
practical existence (avenues, excess loads, earthquakes, movements, etc.).
The study of dimensions is usually undertaken to discover the modular design
of each work and the geometric relations between its various parts, as well as
to translate the most significant dimensions into units of measure of the Roman
age, generally expressed in feet. Sometimes the results are slightly forced,
particularly when the idea behind the use of abundant arithmetical calculations
of various multiples and sub-multiples of feet, and even fractions, is to find
measurements in Roman units that adjust to the most significant dimensions of
the bridge.
This dimensional analysis may prove interesting if and when it is not the
only means used to identify a work, but merely a complementary test. This is
particularly important if it is carried out with excessive yet useless rigour,
employing average metrological values expressed in centimetres, applied either
to the search for relations between different parts of a bridge - the golden
section of between the spans of the Alcántara bridge and Ponte Freixo has been
discovered - or to the adjustment in feet of the most outstanding dimensions.
Finally, we would like to point out the striking fact that many of the
dimensions of Hispanic correspond approximately to whole numbers of feet, and
that certain values (10.40 m, 6.00 m, 4.60 m, 3.60 m, etc.) are often repeated.
The Identification of Roman Bridges
In order to further the probability of successful processes of identification
the stonework must present as wide a set as possible of the features expounded.
Even so, there will be cases in which it will be difficult to reach a definitive
conclusion, and the only option will be to wait for new knowledge and research
to provide a solution.
We have been studying bridges in former Hispania for a number of years
now, obtaining a variety of results, some of which we shall set out here. One of
the most interesting results is that of the Villa del Río and Los Pedroches
bridges in Cordova, constructed on the route of the so-called Via Augusta
between Castulo and Corduba, and traditionally regarded as Roman.
However, certain features of the surviving stonework made us doubt this origin
(Durán 1996, 177-178). The Roman nature of the bridge at Villa del Río seems
justified by the presence of rustic work, by the possibly original symmetric
disposition (it once had a fifth arch that has not been preserved), by the
existence of dovetail holes in the paving of the foundation and by the
typological resemblance to the Italian bridge of Calamone, on Via Flaminia.
Nonetheless, the seamed voussoirs of the ribs and the abutment of an arch in the
set of arch stones of an outlet supported by a narrow pier, appear to us to be
constructional regulations of Moorish origin. A seam is a constructional device
that improves the earthquake-resistant performance of the arch by preventing the
voussoirs from sliding, a contrivance that Roman architects were familiar with
although they did not apply it very frequently (it appears, for instance, in the
wedge-shaped lintels of the theatre in Orange and in the arches on the lower
body of the tomb of Theodoric the Great in Ravenna). At a later date this
resource was also employed in Moorish construction, as can be appreciated in the
Moorish buildings of Andalusia (as, for instance, in the Puerta de Sevilla in
the walls of Carmona, and in the Pinospuente bridge in Granada).
As a constructional composition, the narrow pier measuring 45 cm shared by
two vaults with the same number of outlets is too slender for Roman taste. In
fact it does not appear in any other Roman bridge, not even in the
aforementioned Calamone bridge. Moreover, there is a genuine possibility of it
being unstable under certain circumstances, according to the studies undertaken
(Durán 1996, 178).
The Los Pedroches bridge also presents seamed voussoirs, and here again,
their presence leads us to query the Roman origin of the present stonework, or
of a part of it at least, as its three vaults have obviously been reconstructed
at a later date, still in the Moorish period, with much narrower voussoirs than
those with the seams. In our opinion, both bridges are reconstructions of
previous Roman bridges, of which the original foundation and formal layout have
been preserved.
Another interesting bridge of ancient appearance, of which only the first
courses of rustic work on its piers have survived, is Ponte Ponsul, located some
20 km east of Castelo Branco in Portugal, that stands next to another bridge
completed in 1875 during the reign of D. Luis I of Portugal. Studying them some
years ago, we reached the conclusion that the presence of rustic work was not
sufficient evidence to allow us to classify it as a Roman bridge, in spite of
the fact that its erosion denoted age and that it stood along the route of a
road possibly linking Mérida-Alcántara-Segura-Conimbriga in quite a
straight line. The ogival plan of the cutwaters and buttresses, unknown in the
Roman bridges in Europe yet a common feature in works of the thirteenth,
seventeenth and eighteenth centuries, also made us doubt. However, in a recent
trip to
Tunisia we visited the ruins of the
Roman bridge of Chemtou, over the wadi Mejerda in the ancient city of
Simitthu, and observed that the cutwaters and buttresses also had ogival
plans. Having discovered a genuinely Roman precedent for these initially
disconcerting piers of Ponte Ponsul made us reconsider our first opinion and
take into account the possibility that the remains discovered did in fact stem
from a former Roman bridge.
Another case we have studied in depth is the Roman bridge of Fortanete in
Teruel, which has a segmented arch with a span measuring 10.40 m and a width of
3.60 m. The fact that the stonework of this bridge presents two of the features
previously described, that is, the rustic work of the voussoirs and the
possibility of expressing the two measurements in whole numbers of feet (35 and
20 respectively), not to mention that the flattening of the arch is equal to
that of the original arch of the Alconetar bridge, lead us to believe that this
is in effect a Roman construction. Nonetheless, the sharpness of the arrises of
the voussoirs and of the rustic work, denoting a lack of age, the narrowness of
the roadway and the lack of uniformity in the thickness of the ribs raise doubts
that cannot be resolved until further research provides conclusive evidence for
positive identification.
In northern
Portugal we have analysed two bridges
pertaining to former Gallaecia, Ponte do Arco da Geia over the river Labruja,
near the city of Ponte de Lima, and Ponte do Arco over the river Vizelas,
between the cities of Guimaraes and Amarante. The former has an arch with a
uniform set of arch stones measuring 60 cm high, eroded rustic work measuring
4.00 m wide (13.50 feet) and a span of 10.70 m (36 feet). The latter presents
two vaults, the largest of which is also the oldest and has a span of 12.60 m
(42 feet) and a width of also 4.00 m, with uniform voussoirs measuring 70 cm and
eroded rustic work, while the smaller vault is clearly modern. The fact their
most important dimensions are expressed in feet, that the rustic work of the
voussoirs is eroded, that no traces made by Mediaeval masons are distinguishable
and even that they stand in very Romanised areas close to the Limia and
Salacia mansions respectively, on the route of former road links could
tempt us to believe we are before two Roman arches. However, we do not consider
these factors to be sufficient to identify the works as Roman, despite clearly
belonging to the Roman constructional tradition.
The location of a bridge on the route of a Roman road could be, as in the
case of Ponte Ponsul and in the two previous examples, an issue corroborating
the Roman origin of a construction. Such is the case of Pontarrón de Los
Garabíos, near Valencia de Alcántara, which in addition to being located on a
road that possibly linked the Lusitanian Valentia and the bridge of
Alcántara, has an arcading composed of two equal vaults with spans measuring
8.40 m (28 feet), a width of 4.50 m (15 feet) and some ashlars with rustic work
scattered around the present construction built by the Order of Alcántara. It is
clearly not a Roman bridge, although we do consider it a legacy of Roman
constructional inspiration.
To conclude this essay we shall refer to the remains of a bridge in Pertusa,
Huesca, built over the river Alcandre on the route of Road No. 1 on the Antonino
Itinerary, and the possibility that these be the only surviving elements of the
former Roman bridge. Informed of its existence by the investigator Moreno Gallo,
we observed enough characteristics in these remains to harbour no doubts that
their origin was in effect Roman - the vault was wide (5.70 m/19 feet), the
masonry presented holes to hold the double dovetail cramps, the bond had been
carefully executed and the channelling walls on the upstream side have survived,
as in the case of the Bridge of the Devil in Martorell, Ponte Navea and Ponte
Bibel.
Epilogue
A number of bridges in Hispania that have traditionally been regarded
Roman should be reconsidered, as the constructional and formal analysis of their
stonework would be sure to provide new information leading to a change in
attribution. Among other instances, we believe that the stonework in the Luco de
Jiloca bridge in Saragosse, the Pollensa bridge in Majorca, the Mantible bridge
in La Rioja, the Colloto bridge near Oviedo, the Medellín bridge in Badajoz, the
Tardomar bridge in Burgos and the Cihuri bridge over the river Tirón, also in La
Rioja, should be the object of detailed examination for, from our point of view,
they do not possess sufficient identifying traits nor is there historical data
of sufficient substance to confirm their Roman origin.
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