In the last few years, we have attempted to reconstruct the Roman transport conditions by modelling travel costs and times with the help of GIS and Network Analysis applications. The main geographical focus of this project was the NE of Hispania. It was necessary devote a significant effort to the gathering, documentation, analysis and digitisation of Roman communications with high precision. With the aim of using these methodology in a much broader geographic frame, the entire Iberian Peninsula, Italy and Britain were analysed with less detailed transport networks . It allows us to discover very interesting patterns. The results of such applications provide us with new information to understand the distribution of commodities, product competition and problems of stagnation in ancient economies such as that of Ancient Rome.

1. Network Analysis to understand the
Roman Commerce
Pau de Soto

2. Roman Empire
COHESION
Network Analysis to understand the Roman Commerce
Territory covering all the
Mediterranean, from Northern
Western Europe to Near and Middle
East.
2
Created
Maintained
NETWORK
S

3. Roman Empire
COHESION
Network Analysis to understand the Roman Commerce
3
Created
Maintained
NETWORK
S
All levels of Roman life
Houses
Client
System
Cities
Politic
System

4. Roman Empire
Network Analysis to understand the Roman Commerce
4
NETWORK
S
All levels of Roman life
Houses
Client
System
Cities
Politic
System
Empire - Communication Systems
complex transport
infrastructures
put together a lot of
communities
Political, economical
& social movement

5. The Commerce of the Roman Empire
Network Analysis to understand the Roman Commerce
5
The Project Objectives:
1) An approach to the Roman Transport Network
Morphology
2) Reconstruction of the Roman Transportation Systems
• Which infrastructures did they build?
• How the Romans transformed their territories?
• Does the connectivity of their cities reflect their
political, social or economical interests?
• Can we reply the Roman Transport Movements?
• Can we know the costs and times needed to move Roman goods?

6. Network Analysis to understand the Roman Commerce
1. NE of Iberian
P.
2. Hispania
3. Britannia
4. Italy
1
2
3
4
The Project Evolution:
To study all these
networks it is
mandatory to know
how were the
Roman Transport
System.

7. Network Analysis to understand the Roman Commerce
Divided into:
• Sea
Communications
• Inland Waterways
• Land Transport
The Roman Transport System

8. Network Analysis to understand the Roman Commerce
Two wide spaces:
• Mare Nostrum
• Atlanticum Mare (Mare Externum/
Oceanus)
Maximum support to the economy of Rome
Sea Transport
• Most widespread
• The fastest
system
• Highest
capacities
• The Cheapest• Meteorology
• Closed on winter
• Dangers
(Pirates)
Rome understood the
importance of the maritime
navigation, specially in medium -
long travels.

9. Network Analysis to understand the Roman Commerce
Transport system with big duality:
Downstream
Upstream
Best way to penetrate in inland territories
River Transport
• Fast way (downstream)
• Good capacities
• Cheap
• Needs energy
(upstreams)
• Slow (upstreams)
• Depends on Geography
Limitations:
• Geography
• Climatology (specially on the
Mediterranean)
• Need of building infrastructures
(leeves)
Lots of Roman cities with river
connections:
• Rome
• Londinium
• Caesaraugusta
• Hispalis

10. Network Analysis to understand the Roman Commerce
Only system that connect everyplace of the Empire
Land Transport
• Higher Security
• Access to all
Empire
• Lower capacity
• Slower
• More Expensive
Rome built more than 300.000 kms of land routes.
• These huge road network is used to define Rome as a
truly empire.
• The land transports was the only way to connect all the
cities and territories of the Roman Empire.
• Those roads were used for military, politic, economical
and propaganda functions.

11. Network Analysis to understand the Roman Commerce
The motivations for the construction of
the transport network changed over the
time.
• Support of armies and
colonies.
Networks should
cover all needs
OverTime
• Economic and Political
needs.
• Social and Religious
motivations.
The Roman Transport System

12. How to study the territorial configuration?
How to analyse the commerce?
How explain the movement of Roman goods?
How get close to the mobility of the Romans?
We know the infrastructures and the transportation systems…
Digital Recording
Quantifying the Roman Transport System
GIS
Digitalizing

13. Network Analysis to understand the Roman Commerce
Network Analysis
Transform the reality in nodes (points) and edges (lines)
Transform cities into nodes (points) and routes into edges (lines)
Origin: Graphs Theory by L. Eulen (1736)
Koningsberg
VALUES Calculations
Social Network Analysis
- Accessibility
- Cost & Time
Transport

14. Methodology: Use all available data to obtain the most accurate
reconstruction of the Roman Roads, navigable rivers and sea connections:
Quantifying the Roman Transport System
Digitalizing
Archaeological data:
– Mansiones.
– Milestones.
– Stretches of roads.
– Villae and rural settlements.
– Necropoli, Roman cemeteries
– Bridges, …
Geographic Reality:
− Mountains
− River steps
Historical & Ethnographical Data:
− Medieval - XIXth Cent.

15. Network Analysis to understand the Roman Commerce
Result: High detailed transport network.

16. Network Analysis to understand the Roman Commerce
Acessibility
Main concept:
Cities with higher connectivity
More important settlements
=
Connectivity
Political, economic and social significance

17. Degree Centrality:
Betweenness Centrality:
Closeness Centrality:
Network Analysis to understand the Roman Commerce
Calculating the Accessibility
Accessibility = Centrality:
More intuitive, simple
More connections = More important

18. Network Analysis to understand the Roman Commerce
Calculating the Accessibility
Origin in Social Network Analysis
# edge = # value
2. According to the means of transport
Sea Transport 1
River Transport 2
Land (Main Road) 3
Land (Secondary R.) 4
1. Classic (Sociology)
New method of calculation
1 sea
3,4 river
(downstream)
6,8 river (upstream)
43,4 land (wagon)
50,7 land (donkey)
Value of edges depending on the type of
transport

19. Network Analysis to understand the Roman Commerce
Calculating the Accessibility

20. Network Analysis to understand the Roman Commerce
The accessibility results shows
us the network configuration in
each territory in a specific
historical moment.
Accessibility
Different
periods
Roman Times
(s. II AD)
XVIth Century
Higher values (red/
yellow) show territories
well connected
Important cities
and territories

21. Network Analysis to understand the Roman Commerce
Accessibility - Hispania
Transport
infrastructures were
developed following the
geography, natural
resources (mines) and
military settlements.
Rome was interested in fully exploit the
coast areas and the closer locations in the
river valleys.

22. Network Analysis to understand the Roman Commerce
Accessibility - Italy
Rome built her land
routes thinking in a
political and military
connections
Rome was perfectly
connected with the
rest of the Empire

23. Network Analysis to understand the Roman Commerce
Accessibility - Britannia
Armies in Britannia
Optimize the
metropolis-colony
connections.
London was the centre of the
transport network.

24. HOW? Implement of constant values per
kilometre
Cost & Time
✓ the shortest.
✓ the most economical.
✓ the faster.
Best Route
Network Analysis to understand the Roman Commerce

25. Once we know the length of each trip we can use constant values.
Methodology to import values.
Introducing cost & time values
Cost of travel:
− The length of the trip
− The Costs of transports:
− The characteristics of vehicles
− The load capacities
− Roman prices
Time of travel:
− The length of the trip
− The speed of vehicles
T(time) = L(length) / Sv (speed value)
C(cost) = L(length) * Cv (cost value)
Mule driver, camel driver with maintenance......................25 modii
Water carrier working a full day with maintenance............25 modii
Network Analysis to understand the Roman Commerce

26. Based on classical sources and
archaeology:
Values
1 sea
3,4 river (downstream)
6,8 river (upstream)
43,4 land (wagon)
50,7 land (donkey)
Network Analysis to understand the Roman Commerce

27. The values of speeds and costs are entered
into the GIS as constant values for each
kilometre in route.
Introducing the Values
new tables
1
Each section has its own cost & time
Network Analysis to understand the Roman Commerce
Finally we can calculate the
transport costs & times from
one point to the rest of the
network

28. Closer view to the mobility of the transport
systems.
Time
Ancient sources = temporal patterns / not
distances
The travels were counted
in days and not in
numbers of miles
travelled.
“Go, my little book, go; accompany my Flaccus across
the wide, but propitious, waters of the deep, and with
unobstructed course, and favouring winds, reach the
towers of Hispanian Tarragona. Thence a chariot will
take you, and, carried swiftly along, you will see the
lofty Bilbilis, and your dear Salo at the fifth stage…”
Knowing the time needed to travel is a
important information to understand the
distribution of certain products, especially
those of low durability.
Network Analysis to understand the Roman Commerce

29. Time
Network Analysis to understand the Roman Commerce

30. Time
Network Analysis to understand the Roman Commerce

31. It is the analysis of the movement of
goods
from its transportation cost.
Costs
The goods were
moved until their price
was prohibitive for
commercialization
Observe cost patterns and
influential areas of
distribution
Network Analysis to understand the Roman Commerce
Objective: Not replicate one single travel cost

32. Network Analysis to understand the Roman Commerce
Costs
Firsts analysis in NE - Hispanic

33. Accessibility - Hispania
The territories more accessible were always near
the coast or in areas with river connections.
Inside peninsula was heavily
insulated. This fits with the
archaeological data that is
documented in inland sites.
Network Analysis to understand the Roman Commerce

34. Network Analysis to understand the Roman Commerce

35. Accessibility - Italy
From Arezzo, the natural way to
export was the Tyrrhenian
Sea coast.
Many coastal territories
were easily accessible.
There were important
commercial ports
Network Analysis to understand the Roman Commerce

36. Accessibility - Britannia
Except for points near the coast, many of
hinterland were isolated. This situation is
especially prominent in the northern
territories.
London represented a good
redistribution point of goods
both export and import
Network Analysis to understand the Roman Commerce

37. The Roman Empire was based on a highly organised economical and
political communication network.
Initially, the routes especially by land, were designed according to
military and political criteria to link territories related to Rome.
The organisation of territories was made taking into account the
advantages of geography, building cities along the coast and in easily
accessible river valleys.
The model of communication in Italy was very different from Hispania
and Britannia.
The Italian model was configured in a long time, and did not respond
especially to an economical criteria.
Hispania and Britannia were seen as models of land exploitation.
Conclusions
The Roman Empire
Network Analysis to understand the Roman Commerce

38. The study of the Roman transport network is very necessary to
understand the roman economy and history.
The transportation network in Roman Times was indispensable to
keep together the territories with such heterogeneous cultural
background.
The political integration required integration in terms of economy and
communication.
The transport network was a key factor in the success of the Roman
Empire.
Conclusions
The Roman Empire
Network Analysis to understand the Roman Commerce

39. It is an unfinished project.
But it can shows some interesting results.
It provides new data to the study of economics and history
of Rome.
The Network Analysis provides us new information on
past transport conditions to better understand past
economies.
A more complete study of the whole network, province by
province, is required to understand all the Roman
transport system.
GIS is an exceptional tool for modelling transport and
accessibility
Conclusions
Project
Wider territories
More detailed
Network Analysis to understand the Roman Commerce