Engineering Rome

An Assessment of the Sustainability of Roman Urban Design

By Bhagat Subedi

Photos are by the author unless otherwise stated

As a new age of human development and technology dawns upon us, the everchanging and imminent challenge of sustainable development threatens our culture and urban design. Almost 55% of the world’s population resides in urban areas currently, and by 2050, that figure will jump to 68%, per projections (UN, 2018). Such a drastic shift in human behavior has not occurred since Ancient Times. This rapid and presumably uncontrolled growth calls for a new framework and approach to urban design. This advancement must balance economic growth with environmental and resource prioritization. The challenge lies in adequately providing housing, energy, infrastructure, and necessities for the growing population. 

Figure 1: Map of Central Rome (Britannica)

The City of Rome presents an interesting case on this front. Specifically, its historically-sustainable architecture positions it as a leader in the new age of urban design. This paper analyzes and assesses the sustainability of the urban design of modern-day Rome. It also describes current regulations and policies in the city and their effects on sustainability. As a recent visitor to Rome, I provide supplementary observations on Rome’s urban design and development. Finally, this paper suggests possible changes that can be implemented to optimize sustainability in the Eternal City.

Historical Urban Design in Rome

Rome has always been a large city, even by modern standards. Until the Industrial Revolution, there were no cities in Europe of a similar scale. It posed unique predicaments, such as the simultaneous balance of historically closely-packed neighborhoods with increased urban sprawl. The sheer size of the city also required a vast level of organization. During the height of the Roman Republic and Empire, the city employed commissions for provisions on building maintenance, floods, water supply, and fires. Interestingly, the Romans did not observe a need for commissions on public transport, education, or housing (Robinson, 1992).

Figure 2. The remnants of the Forum, the ancient center place for day-to-day life (Live Science, 2022)

Most building regulations in Ancient Rome limited the height and space left around buildings and application materials. Interestingly, limitations were also placed on wall thickness which comprised verticality in the city’s development. This effect can be seen in the modern layout of Rome, as it sprawls much more than it builds up (see Figure 3). The exorbitant size of the city poses difficulties in arranging transportation systems, organization, congestion, and waste management, just to name a few.

Figure 3. Rome as seen from the Vatican

When visiting Rome, I immediately noticed the vast network of roads overlaying the city. The arterials were obviously modern-age, and were constructed to carry automobile traffic, inevitably reducing the walkability wherever they were operating. The old roads, however, were all extremely narrow, comfortably accompanying one car at a time, and led into expansive piazzas and open areas (see Figures 4 and 5).  

The Romans were neither the first nor the only ones to construct extensive roadways- Egypt, Persia, and India all did it before them. The Romans differed because they created a vast roadway system to the extent the world had never seen before. It weaved through all its territories and connected with all ports and sea routes in the sprawling empire. Most of this network, often constructed from stone-overlain Pozzolan Concrete, was also built for public access, which was rare. Because of this, modern-day Rome is one of the most walkable cities amidst an age of car-centric urban design (see below).  

Figure 4. The Open Roads in Front of the Spanish Steps
Figure 5. Piazza del Popolo

This roadway system was the very foundation for Rome’s expansion and spread. Raw materials, merchants, art, cultural currents, crafts, and resources spread throughout the empire on these routes. It brought together fashion, culture, people, legends, stories, religions, inventions, artistic influence, philosophical theories, and knowledge.

Figure 6. Ancient Roman Road in Pompei

The Case of Roma

The three most assessed and studied urban forms in urban planning are the compact, the polycentric, and the sprawled. For clarification, the polycentric urban form is one where the location of activities concentrates around dense urban centers. Most ancient cities followed this model. The Roman urban form is quite peculiar in this case. Because of its historical urban development, Rome can classify as a compact, polycentric, or sprawled urban form. Each form presents new obstacles on the road to sustainability. 

The compact form often causes severe congestion in transport networks and increases land prices (Breheny, 2009). Furthermore, exposure to noise and air pollution in urban environments leads to detrimental health impacts. Polycentric models are a much-debated idea, as it is unclear if they effectively reduce automobile trips and emissions. Finally, sprawled urban forms conclusively induce car-oriented lifestyles and higher management costs through waste control and energy use (Coppola et al., 2014). Rome features one of the highest car-ownership figures in Europe, as 85% of people own a car or vehicle (Gore-Coty, 2017). 

The extreme effects of sprawl have been felt as recently as 100 years ago, specifically in the Roman Campagna. The Roman Campagna is a low-lying plain surrounding Rome. The region is bounded by the Tolfa mountains in the northwest, the Sabini mountains in the northeast, the Alban hills in the southeast, and the Tyrrhenian Sea in the Southwest (Britannica). In ancient times this 800-square mile area was of much cultural and residential importance. However, it was abandoned in the middle ages due to malaria and insufficient water supplies. Interestingly, the pastoral beauty of the region suddenly attracted flocks of painters and tourists in the 18th and 19th centuries. The Campagna became the most painted landscape in Europe at one point (see below). The region was then reclaimed in the 19th century for its farming applications. The uncontrolled building development and expansion have destroyed much of the natural landscape in the Campagna. This is one of just many cases of sprawl wreaking havoc on natural areas, specifically in Rome.

Figure 7. Roman Campagna Painting “Morning Light” by William Stanley Haseltine, 1871

The concerning elephant-in-the-room when discussing Rome is the issue with pollution and air quality in the city. According to a study conducted by the Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA), mortality risk in the city is anticipated to rise 8% by 2050 due to a combination of rising temperatures caused by greenhouse gas emissions and pollutants in the air, such as PM10 (Michetti et al., 2022). According to the study, in the coming decades, the City of Rome could reach a mortality rate of 591 deaths per year, about 8% higher than previous decades, during the summer months, due to higher temperatures and unsafe concentrations of tropospheric ozone. It is estimated that 22% of summer deaths would be directly attributed to air pollution. The study concludes by highlighting the urgent need for climate regulations, as a temperature increase of+1.5C by 2100, as opposed to the current goal of +2C, would reduce deaths by a factor of eight in Rome alone.

Assessing Modern Regulations and Developments

Traffic-Restricted Zones

One of the largest traffic-reduction systems implemented in Rome today is the Traffic-Restricted Zone, also known as the “Zono a Traffico Limitato” (ZTL) in Italy. ZTL’s restrict influx traffic so that only authorized vehicles can enter certain zones. In Rome specifically, only Rome-residental vehicles are granted authorization to these zones. ZTL’s are employed to reduce the intrusion of automobiles in city centers and subsequently reduce the air and noise pollution in these areas. Secondary effects include increased bicycle and pedestrian mobility, improved pedestrian safety, improved air quality, and reduced congestion.

In 1989, the ZTL was implemented into the Italian Highway Code, which specified who had the authority to enforce them, the fine for violations, and general guidance for implementation. That same year, Rome implemented its first ZTL, as shown below. Specifically in Rome, there was a priority to protect historical areas such as the Forum and Colleseum, which were being degraded by the presence of automobiles. In 2015, the ZTL had expanded to 1.6 square miles in seven distinct zones, each with their own hours and conditions (DeRobertis & Tira, 2016). The boundaries of the ZTL’s also changed, from signs, which were difficult to enforce, to police-manned gates, to license-recognition cameras and software, which are used to this day.

Figure 8. Original Rome ZTL (orange) and later expansion (purple) (DeRobertis & Tira, 2016)

ZTL’s are not traditionally quantitatively assessed for their effectiveness, as they are almost always assumed to reduce traffic, pollution, and congestion. However, in 2014, Rome evaluated the effectiveness of ZTL’s based on several factors, and concluded that they resulted in 5.0% decrease in car trips, 3.6% increase in public transport trips, and a 1.5% increase in pedestrian and cycling trips (City of Rome, 2014). A prior study conducted by the City of Rome found similar results, as well as a reduction in air pollution and increased travel speeds for buses (City of Rome, 2004). ZTL’s seem to be an effective way to reduce congestion, air and noise pollution, and degradation, while promoting more sustainable modes of transportation. Logically, the next step will be to further expand these zones with consideration to traffic trends and data.

The Struggle between Archaelogical and Developmental Priority

The particular challenge of development and reform in Rome lies within the historical groundwork of the city. First, Rome is vast in size, population, and diversity. I spent a month in Rome, and even then, I had not scratched the surface of the metropolis. For reference, I reside in Seattle, WA. Rome is nearly six times larger in area and population than my native town (Istat, 2018)- maintaining 496 square miles of a sprawled ancient city, with countless historical neighborhoods, landmarks, and groups of people is a daunting process. Mainly, drastic construction projects are painstakingly time-intensive, mainly because of the excavation process. Nearly all excavation in Rome inevitably leads to archaeological discoveries, thus halting the project. The most glaring example is the painfully long Metro C Line project (see below), which started in 2006, and is already 20 years behind schedule (PBS, 2019). The C Line seeks to run from Eastern Rome (Monte Comprati) to the Colosseum. This common predicament freezes nearly all vast construction projects, whether transportation, foundation, utility-based, commercial, etc. Furthermore, the city is already as compact as feasible, making it nearly impossible for projects such as bike lane expansions. For these reasons, transportation network improvements are far and in between.

Figure 9. Proposed Metro C Line Traffic Network (Wikipedia)
Figure 10. Metro Line C Active Construction (September 2022)

Accessibility, or there lack of, in the Eternal City

While on my visit to Rome, the glaring walkability and sustainability issue I noticed was the lack of accessibility, or in this case, “wheelability”. Most roads in the city are old, degraded, and cobblestone-lain, making it difficult for a large percentage of the population to traverse. For example, notice the wildly uneven and inaccessible cobblestone typically seen in Rome’s streets below in Figure 11. Certainly, sustainability in a city must consider “wheelability” and the ease of access & transportation for bikers, the elderly, people with disabilities, young children, and so on.

Figure 11. A walk through Roma (Muench, 2022)

Similarly, accessibility for these same groups of people is often negligent at the city’s most busy and popular locations. For example, Trevi Fountain, as seen in Figure 12, is difficult to view for anyone with disabilities or who is wheel-dependent. While wheelchair accommodations are present, according to several tour guides, it is commonly stated that accommodation is difficult due to crowding. This is also the case for many other attractions, like the Colosseum and the Spanish Steps (see Figure 4). Years of neglect make these areas inaccessible and frankly, undesirable for those with disabilities. Under current legislation dating back to 1986, Italian municipalities are required to remove all architectural obstructions. Despite this, less than 5% of municipalities have done so (Euro News, 2022).

Figure 12. Trevi Fountain

Summary and Strategies for Future Sustainable Urban Design

In the grander scope of the world, Rome is one of the most sustainable and walkable urban environments. However, as we have explored, there is still much work to be done. The inherent groundwork and historical presence of the city make it extremely difficult to conduct major construction and renovation projects. The city quite literally encompasses nearly 3000 years of history through its urban design. The largest issues facing the future of Rome are the loss of natural resources, loss of natural areas due to sprawl, air pollution, congestion, overcrowding, and climate change.

Rome currently boasts one of the highest automobile-ownership rates in Europe, making it even more challenging to control degradation in the city. Traffic-Restricted Zones (ZTL’s) are used to combat this problem in historical or busy areas, to minor success. The city is also riddled with accessibility issues for people with disabilities, the elderly, bikers, and wheelchair-riders.

The future for Roman urban design, on the other hand, has the opportunity to revitalize and transform the city into a truly sustainable one. albeit through painstaking and meticulous law-making and engineering. Potential ideas include natural resources and environmental regulations, expansion of ZTL’s, electric-fueled public transport, new public transport vehicles and stations, limiting consumption of building materials for infrastructure, and exploration of renewable energy sources.

It is also critical that verticality is optimized in the coming decades. Not only does this provide an ulterior method for expansion, but it helps to reduce temperatures throughout the city streets and piazza’s.


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