Britain’s Roman roads are distinctive in several aspects. Firstly, they formed an interconnected network predominantly centred around London. Secondly, their construction was concentrated within a relatively short period, from 43 AD to 81 AD.
Intriguingly, this timespan is roughly equivalent to the period over which the current UK motorway network was built. As depicted in Figure 1, this network extended as far north as modern-day Perth, with some roads even built north of Hadrian’s Wall.
A notable characteristic of British Roman roads was the use of the ‘agger’, an embankment typically ranging from 300mm to 1.5m in height, forming the foundation for the roads. The agger was constructed using material excavated from ditches running alongside the road.
Contents
Aggar
Britain’s Roman roads are distinguished in several ways. Firstly, they formed a cohesive network, predominantly radiating from London, and secondly, they were constructed within a relatively short timeframe, between 43 AD and 81 AD. Interestingly, this period is roughly equivalent to the time taken to construct the current UK motorway network. This network stretched as far north as modern-day Perth, with some roads even extending beyond Hadrian’s Wall.
A distinctive feature of these British Roman roads was the use of the ‘agger’, an embankment ranging in height from 300mm to 1.5m, which formed the base of most roads. This agger was built using material taken from ditches dug parallel to and beside the road.
Read More: Roman Roads of Britain, The Ancient Highways
The purpose of the agger has been the subject of speculation; some believe it served an engineering role, aiding in water drainage from the road surface, while others suggest it was for security reasons. Given the initial hostility of the Britons following the Roman invasion, the agger might have provided strategic advantages, offering Roman travellers not only an elevated view but also a defensive position against potential attacks.
It’s important to remember that two thousand years ago, Britain was largely forested, and these roads were constructed through areas cleared of trees, often extending up to 30m wide, despite the roads themselves usually being less than 10m wide. This extensive clearing was likely done to improve security and perhaps to make the roads more navigable.
Straight Roman Roads
The renowned straightness of Roman roads is often noted but is less remarkable than it might initially seem. The straight line, being the shortest distance between two points, naturally required the least effort in construction. Roman surveyors used instruments capable of extending any two points into a long, straight line. Additionally, with their background in sea navigation, it was logical for Roman surveyors to favour straight, direct routes for land communication.
However, the Romans were not rigidly bound to constructing straight roads and would frequently create detours to circumnavigate natural barriers like valleys and hills. It was common for roads to deviate at hilltops, where extending a straight line would have been more challenging.
Read More: Roman Forts Still Litter Our Countryside
In Northern Britain, where the terrain is more mountainous, deviations from straight routes were more common than in the flatter southern regions. The width of Roman roads varied, with major routes typically around 10m wide, other principal roads about 8m wide, and most minor roads around 5m wide. In urban areas, streets were often no wider than 3m, as seen in many of the narrow streets of Pompeii.
Ditches
After clearing a path through the woodland, edge ditches were excavated to delineate the road’s boundary. The material from these deeper ditches alongside the road was then utilised to construct the agger.
Typically, the material from the agger ditches was laid directly onto the existing ground level, with no effort made to remove the topmost loose material. When the agger reached about one metre above ground level, large, roughly hewn foundation stones, as they arrived from the quarry, were placed.
Over these foundation stones, a layer of coarse crushed rock or gravel was added and compacted. Longer edge stones were positioned at the sides to contain this layer. Generally, two layers of crushed rock or gravel were used; the top layer consisted of smaller-sized material and was occasionally cemented.
Read More: Gladiator Battles: The Roman Amphitheatres of Britain
The final road surface was then constructed using smaller cobbles, which were precisely cut at the site to ensure a snug fit. The laying of these surface stones incorporated principles akin to modern-day paving technology. The integrity of the surface depended on interlock, meaning that no individual stone could move independently from its neighbours under traffic.
This interlocking effect resulted from the high precision achieved in stone cutting. The scarcity of archaeological remains from these road surfaces can be attributed to the precision of the stone cutting, which made the stones highly valuable as construction materials in later periods.
Britain’s Roman roads Scant Evidence
There is scant evidence about how traffic was regulated on these Roman roads, yet considering that Roman carts were typically less than 2 metres wide, it seems plausible that the main roads could have supported three lanes.
The question of whether there was a specific rule dictating which side of the road to travel on remains a matter of speculation. However, it seems probable that travellers would have predominantly used the centre of the road, only moving aside to overtake someone coming from the opposite direction.
Alongside the large ditches from which material for the agger was extracted, smaller ditches were also constructed on both sides of the road, parallel to it. These narrower ditches, usually about 1 metre wide and 300mm deep, were spaced either 27 metres or 20 metres apart.
Motorway Fences
They likely demarcated the boundary of the road zone, similar to the function of motorway fences today. The structure of the road thus consisted of the agger running down the middle of the cleared zone, flanked by large ditches – at times up to 3 metres wide and over a metre deep – on each side, followed by an area on each side of the agger approximately equal in width to the agger itself.
Read More: What Happened to Britain’s Roman Roads?
In total, four parallel ditches were excavated: the two smaller boundary ditches at the outer edges of the cleared space. There’s limited evidence regarding traffic management on Roman roads, but given that Roman carts were typically less than 2 metres wide, it’s plausible that the main roads could have supported up to three lanes.
The existence of any specific road rules, particularly concerning which side to travel on, is still a subject of speculation. However, it seems likely that travellers would have generally used the centre of the road, moving aside only to let someone travelling in the opposite direction pass.
Britain’s Roman Roads Boundary Ditches
Beyond the large ditches from which material for the agger was sourced, smaller ditches ran parallel to each side of the road. These were typically about 1 metre wide and 300mm deep, spaced apart by either 27 metres or 20 metres.
These smaller ditches likely marked the boundary of the road zone, similar to modern motorway fences. Thus, the road included the agger in the centre of the cleared area, flanked by large ditches, sometimes up to 3 metres wide and over a metre deep, on either side.
Then, there was a space on each side of the agger, approximately as wide as the agger itself. In total, four parallel ditches were constructed – the two smaller ones marking the boundaries of the clearing and the two larger ones beside the road, the excavated materials from which were used to build the agger.
Read More: How Did the Romans Drain the Fens & Somerset Levels?
Following the end of Roman governance in Britain in 410 AD, Roman roads gradually fell into disuse, offering a wealth of information about construction materials more so than their counterparts on the continent. These continental roads often remained in use and, as a result, underwent periodic reconstruction.
The Anglo-Saxons
After 410 AD, the British Roman lifestyle began to decline as the Saxons and the Picts initiated their incursions. By 450 AD, Roman influence in Britain had diminished, and the Roman road system started to deteriorate. Wooden bridges deteriorated, and strong winds frequently caused fallen trees to block the roads, effectively turning them into disconnected short segments.
The Saxon economy, centred around local marketplaces, diminished the need for long-distance travel. The Roman aggers found new use under the Saxons as boundaries for farmland. The roads that continued to be used faced increased traffic during the Middle Ages.
When turnpike roads were constructed in the 16th and 17th centuries, materials from the Roman aggers were often repurposed for these new constructions. In instances where new roads aligned with the old Roman roads, the agger was sometimes spread out to serve as the foundation for the new roadway.
Read More: A Trip Along Watling Street, The Longest Roman Road in Britain
Due to neglect and plundering, only limited sections of high-quality Roman roads remain in the UK today. Much of our current understanding of these roads comes from recent construction projects that have uncovered sections of Roman roads, sometimes documented for historical records.
Britain’s Roman Road Network Lasted
Notably, the Roman road network lasted for 350 years, a remarkable example of a major civil engineering project fulfilling its intended purpose with minimal changes over several centuries.
This longevity underscores the importance of understanding how these roads were constructed and the materials used. By comparing ancient Roman road-building techniques with contemporary road-building standards, we can gain insights into the future of road construction.
Interestingly, recent advancements in paving systems mirror those made by the Romans. In the early days of the Republic, roads were primarily gravel-surfaced, but by the time of Britain’s conquest, major roads were typically paved.
Read More: The Forgotten Roman Roads
The precision of Roman paving is noteworthy; one Roman standard required that the gaps between paving stones be so narrow that a Roman soldier’s knife could not fit through them. This implies joint spacings of less than 3mm, a detail highly relevant to current European highway paving specifications.//
Britain’s Roman Road System
The Romans first set foot in Britain in 55 BC and returned the following year. On both occasions, Julius Caesar was unable to establish Roman control, although he did reach St. Albans in 55 BC before withdrawing back to continental Europe.
During this period, Britain was home to various tribes, largely speaking a common language. The four dominant tribes were the Catuvellauni in the Southeast, the Silures in South Wales, the Brigantes centred in the Vale of York, and the Caledonians in the Grampian Hills and Eastern Scotland.
Notably, three significant pre-Roman roads – Harroway, Icknield Way, and Jurassic Way – emanated from Stonehenge. In contrast to their approach in other conquered regions where they used and sometimes enhanced existing roads, in Britain the Romans developed an entirely new road system.
Read More: Corpse Roads, Coffin Roads, a Medieval Legacy
After Emperor Claudius’ successful invasion of Britain in 43 AD, road construction initially started in the Southeast and the South Midlands, as the Romans extended their reach from Rome. Following their crossing of the Thames at London, the first major town captured was Colchester, the capital of the Catuvellauni, which then became the administrative centre of Britannia, Rome’s newest colony.
The rest of Britain was subsequently brought under Roman control by legions operating from Colchester, advancing both northward and westward. For instance, the Fourteenth Legion progressed along what would later be known as Watling Street, and the Ninth Legion moved northward, facilitating the construction of Ermine Street.
Defeat of Boudica
By 50 AD, a significant road network had been established in Southern England. However, the hilly terrain of Northern England and the Welsh mountains presented considerable challenges, both from an engineering perspective and due to the local Britons’ resistance to Roman rule. Conflict persisted in Wales and the North throughout the 50s.
In 61 AD, Queen Boudica, often referred to as Boadicea, led the Iceni tribe of East Anglia in rebellion against the Romans. Initially, Boudica’s forces decimated the Ninth Legion, but they were eventually overcome by reinforcements from the Fourteenth and Twentieth Legions.
Read More: Wayside Crosses, What Exactly Are They?
This conflict resulted in the destruction of St. Albans, Colchester, and London. The Ninth Legion’s honour was restored in the 70s when they regrouped at Lincoln and successfully campaigned against the Brigantes, capturing York.
Following the defeat of Boudica and the subjugation of the Brigantes in Yorkshire, Roman road construction resumed in Northern England. Julius Agricola was the first to extend Roman road building into Scotland, reaching as far north as Strathmore.
He advanced Roman control in Northern England, utilizing the Ninth Legion in the east and the Twentieth in the west. These legions employed local labour to construct roads, including three key cross-country routes: Stainmore Pass between Catterick and Carlisle, Stanegate from Newcastle to Carlisle, and a road along the River Tweed.
The Roman Road ‘Ladder’ Strategy
This ‘ladder’ strategy of using two main roads as vertical elements and cross-country roads as horizontal rungs was a tactic previously successful in Italy and later employed in North Africa.
Read More: The Medieval Market Cross, What are They?
Stanegate served as an access route for constructing Hadrian’s Wall, which was not a border of the Roman Empire but a linear fortification built through a remote and challenging part of the Empire. Due to the difficult nature of the British tribes, Roman Britain experienced a significantly greater military presence than any other Roman colony.
The inaugural main road constructed by the Romans was Watling Street, stretching from Canterbury to London, following their initial landing at the ports in East Kent. Southampton and Poole, designated as military harbours, led to the early construction of roads along the south coast.
These roads were subsequently extended to reach Cirencester and Bath in the west, and further to Dorchester and Exeter, with branches heading north towards the Bristol Channel. By 50 AD, roads had been built up to Gloucester, where a fort was also established.
Read More: Corpse Roads, Coffin Roads, a Medieval Legacy
After Watling Street connected to London, further roads were developed from London to the west, northwest as a continuation of Watling Street, northwards (Ermine Street), and northeast. Significant tribal capitals at St. Albans (Verulamium) and Colchester (Camulodunum) were linked by roads from London, likely intended to showcase Roman supremacy to the local populations.
Roman Navy
East Anglia emerged as a pivotal region for road building, with a network extending as far north as The Wash, with Ermine Street serving as a key arterial route to the Humber and further north. Ermine Street was the first major road built in Eastern England, with additional roads intersecting it being constructed later as Roman control spread through the area.
For instance, one route connected Ermine Street to a minor port near Caister in Norfolk, and Lincoln was linked to The Wash, a significant protected haven for the Roman navy.
Watling Street, extending northwest from St. Albans through Towcester to Leicester, was built in distinct segments as the Romans gradually expanded their territory, with additional branches being constructed later. Fosse Way, noted for its remarkable straightness, diagonally traverses from Lincoln through Newark, Leicester, Cirencester, and Bath, terminating in Exmouth.
Roman Fort
Originally established in the Midlands around 47 AD, Fosse Way served as a connecting road marking the boundary between the fertile agricultural lowlands of Britain and the northern highlands. This is evidenced by numerous roads approaching Fosse Way from the southeast and intersecting it at right angles, indicating its role as a frontier.
Read More: Ridgeways, our Prehistoric Road System Before Roman Roads
As Roman expansion continued into England’s highlands, Ryknild Street was developed through Alcester, Birmingham, Derby, Chesterfield, culminating at the Roman Fort of Templeborough in Rotherham.
This road is believed to have marked the temporary extent of Roman control up to around 70 AD, with the Romans having occupied land to the east of this road but not yet to the west.
The Northern Frontier
By 73 AD, the northern frontier was extended to a line from the Humber through Doncaster and Manchester to Chester. In 78 AD, Julius Agricola conquered North Wales, ensuring that by that year, all of Britain south of a line from the Humber to the Mersey was under Roman rule.
The remaining Roman conquest of Britain and the construction of roads north of this line occurred over the next three to four years. Dere Street served as the main road along the east coast, while a second key northern route ran closer to the west coast through Lancashire.
The development of cross-country northern routes came later, notably the road that paralleled Hadrian’s Wall, which wasn’t constructed until the wall itself was built between 122 and 126 AD. Dere Street extended further northwards towards Edinburgh, connecting with roads leading to Strathmore and branching out to the east coast ports.
Roman Road Surveyors
The Romans realized the relative ease of transporting goods directly north by sea compared to the more hazardous overland journey through Britain. The rapid construction of the Roman road network is particularly noteworthy, especially considering the resistance from local tribes.
The Romans appear to have employed the conquered populace as labourers for road building, overseen by Roman soldiers and based on plans laid out by Roman surveyors. The ‘coloniae’ system, initially developed in Italy, was implemented in Britain, fostering prosperity in the subdued regions.
Read More: Corpse Roads, Coffin Roads, a Medieval Legacy
This led to a period of stability that lasted for around 350 years of Roman occupation, with this stability being largely reliant on the communication network provided by the Roman roads.
All the functions of the roads previously mentioned took place in Britain, resulting in the roads significantly contributing to the country’s wealth. Settlements rapidly emerged along these routes.
Notably, the Roman forts along Hadrian’s Wall quickly became the nucleus of surrounding townships, as the local population began to meet the supply needs of the Roman military. It is likely that the growth of this trade facilitated the end of hostilities and fostered the development of a relatively strong economy in Britain.
