Publish at March 15 2023 Updated March 15 2023

Public lighting and urban mutations [Thesis].

The saga of light and the smart city

"Time brings everything to light".            Thales.

Victor Bayard's thesis considers the articulation of digital networks to public lighting networks on the territory of the city of Paris. It can be read as a veritable historical saga of light, night, and the organization of networks in a given social and political context.

As is often the case in theses, we find the roots of established facts or commonplaces, which invites us to examine their relevance and informs us about their scientific value.

So, when we work with land planners, which has been my case in Paris, we always find the question of public lighting as a safety solution.

The functions of public lighting

This is indeed one of the eight functions of public lighting, as established in 1981 by Abraham Moles, and which are still somehow operative :

  • The general function.
  • Of markup.
  • Psychomotor.
  • Ambience.
  • Safety.
  • Enhancement.
  • Visual promotion.
  • Show.

"At night, all cats are gray"

In the work meetings I've been able to attend, women are often taken to task on the issue of lighting and safety. It's often about asking us to validate the connection between a brightly lit city and a gendered, personal sense of safety. In my case it's the opposite. When I am a shadow between two candelabras, the Meuse and the hillsides, I become a mere human again, walking freely at whatever time I please.

"This safety character of public lighting is subject to debate with regard to its real impact on the safety of individuals, its existence in the processes justifying lighting is nevertheless proven."

See on this subject in particular the article by Sophie Mosser, Lighting and safety in the city : the state of knowledge.

Lighting for power

The idea of lighting, however, has been well associated from its earliest implementations with a security and power enterprise. In 1318, it was decided by royal ordinance that a candle be lit near the door of the court palace in Châtelet. This ordinance endowed the city with its first public lighting.

The widespread lighting corresponds to an enhancement of power and security control : in 1408, during the passage of the prince-bishop of Liege (then in a troubled political situation) in the French capital, a large part of the Parisian territory was lit. The economic power is also illuminated : in 1720, lanterns were hung in commercial streets.

These "technical infrastructures [are] determined by the social segmentation of their location.


The origin of the brown color code of Parisian street furniture is also found in this thesis. It dates back to the Second World War, when it was a matter of covering the copper of the candelabras, so as not to arouse the covetousness of the German occupiers.

The night. What are the reasons that drive "human organizations to lighting aimed at chasing the darkness"? An action performed at night reverses the natural course of events and thus has the potential for disaster.

Lighting at night then appears as a desire to reduce "philosophical indeterminacy and amoral", and a means of lengthening production time by stretching the diurnal rhythm. It is a constructed common need that has moved from being an assumed need to being a public service.

"Public lighting transforms the relationship to the night and to each other."

The networks and the "seamless fabric"

The history of the lighting networks shows its articulation with the other networks of the city : the roadway, the water networks, the sewerage networks, the electricity networks, etc. Historically, the zones and techniques have been set up for economic reasons, territorial status. Technical choices alone do not exist and the current network reality is a reflection of this history and these multiple decisions.

The dialogue positioning between urban ideals and physical infrastructure is continuous over the entire history of urban lighting.

Also, "the network keeps trace of non-technical choices, which is a massive argument in favor of the seamless fabric theory.

The "seamless fabric" is a theoretical model proposed by Thomas Hughes. It is to say that technique and society are not separate, "innovation processes emerge from this seamless fabric". Technique is seen as a "modality of association, neither absolutely central nor completely marginal".

"The thinking [developed in this thesis] is constructed, however, in critique of technological positivism and in placing the technical artifact in an ambivalent social relationship to socially-forming social interactions."

From the'age of the Moon to that of thea LED

What are the techniques of light production in relation to their technico-urban evolution? For dating, AEC means before the Common Era and EC Common Era (periods equivalent to Jesus Christ, the EC formulation takes them out of a specific cultural referent). These are :

  • The Lunar Age (100,000 AEC - 17,000 AEC) | Absence of street lighting in urban areas.

  • The Solid Age (17,000 AEC - 17th century EC) | (Fires, candles)Dispersed punctuations, successive punctuations.

  • The Liquid Age (17th - 19th century): first city-wide street lighting in Amsterdam in 1800. The lighting consists of oil lanterns. The security function begins to emerge there, the halo of light is larger | Sprinkled punctuations, successive punctuations, static system in proto-network.
    "Public lighting devices are structured [...] at the same time as the police are organized and the architecture and urbanism are streamlined incipient."
  • The gas age (19th - 20th century): gas lighting (principle invented in France and applications developed in England) fulfills the functions of atmosphere and spectacle and determines new living spaces. Urban morphology is in dialogue with the lighting system | Dynamic retistic system.

  • The electric age (19th - 21st century): electric lighting fulfills all the functions of light as defined above by Abraham Moles | Dynamic retistic system and open system.

The smart city

After interviews of the smart city actors, the researcher was able to consider the terms smart city, Smart City, or digital city, as a illusio in the bourdieusian sense.

That is, "a sociological object that allows different actors to pursue a common but unclear goal, while respecting the rules of the game and yet not being fooled by that unclearness."

From an operational perspective, "the street lighting network is now in charge of changing the city through digital technologies". The smart city covers devices of:

  • Telemanagement, remote control of Parisian street lighting.

  • Presence detection, with dimming of the light flow according to the presence of users (e.g. sensors on the banks of the Seine).

  • Physical support, connections with the drinking water network with misters in the lighting masts, vegetal corollas (freshness during the day and lighting at night).

  • Electricity distribution, especially for electric vehicles.

  • Extinction or intelligence by absence, reduction of lights in moonlight, early evening and late evening light plans.

Action research

The last part of the thesis presents the action research around the DataCity Paris program. The city of Paris delegates the organization of the smart city innovation process to a company. Partner companies are invited to pool resources to develop an innovative project. Start-ups are then selected around challenges determined by the partners.

"We find, in the current arrangements, the same echoes as when gas was giving way to electricity. The municipality, anxious to evolve the network, delegates innovation to an outside company while retaining heritage ownership as well as leeway over the terms of the contract."

To conclude (and this is an invitation to read the saga)

"This is the substance of our thinking and the fruit of our research, the ability to affirm that this very specific infrastructure that is the Parisian public lighting network and by extrapolation urban infrastructures in general, are neither fundamentally technical objects, nor purely social objects but that their trajectories and their modalities of existence are due to a permanent socio-technical dialogue."

"[...] it is not systematically necessary to produce a social counterpart to a technical study and vice versa. On the other hand, it seems salutary to us to understand some of the unthinking that arises from the sometimes arbitrary separation of technique and society in the study of urban infrastructure.

Illustration: Mat Napo from Unsplash.

To read:

Victor Bayard, Participation of the public lighting network in the processes of urban mutations, Paris Est, 2022.

Thesis available for consultation at:

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