Eugène Hénard

Royal Institute of British Architects, Town Planning Conference London, 10-15 October 1910, Transactions (London: The Royal Institute of British Architects, 1911):345-367.

Hénard (1849-1923) was the son of an architectural professor at the Ecole des Beaux-Arts in Paris where the younger Hénard earned his diploma in 1880. Two years later he began a lifetime career at the Paris office of public works. Although he designed a few buildings, including one each at the Paris expositions of 1889 and 1900, he spent much of his time studying the problems of traffic circulation in Paris and proposing solutions for the problems created by the few adequate radial thoroughfares. He also developed a series of proposals for additional parks in the city and for housing to be built along a ring road that would replace the outmoded fortifications of Paris.

He is perhaps best remembered for his diagrams of major European cities that emphasized their radial and ring road patterns. Some of these appear in early American planning reports, notably Daniel Burnham's plans for San Francisco and Chicago published during the first decade of the century. Hénard went well beyond these analytical studies to plan for the further development of Paris, and Burnham also used this design for one of the illustrations in his Chicago plan. The paper that Hénard prepared for the London conference on town planning in 1910 reveals another Hénard--a futurist enamoured by technology and the possibility of near-universal use of private aircraft.

My purpose is to inquire into the influence which the progress of modern science and industry may exercise upon the planning, and particularly upon the aspect, of the Cities of the Future.

It is not without a certain feeling of hesitation that I approach the question: my previous works on Paris have been concerned with subjects which were more clearly defined and which rested upon experimental data. To-day it is my duty to speculate upon mere hypotheses, which, though more or less justifiable, have no established foundation, a circumstance which leads necessarily to hazardous, and sometimes entirely erroneous, conclusions. Even in the most methodical inductions, the exact line of demarcation between the probable and the imaginary is very difficult to draw: nevertheless, I shall endeavour to keep my arguments within reasonable limits; although I dare not affirm that on certain points I may not, unwittingly, be carried away by so seductive a theme. I shall make a special effort to describe the considerations which must determine the form of both our houses and of our streets, as these constitute. the primary elements out of which a city is built up.

Whatever form its future expansion may take, there will always remain, in every large urban community, a centre of intense activity wherein the buildings will always be placed close together, as they are in our cities of the present day. It is a portion of such a centre that we are about to examine.

In the first place, let us consider the defects presented by the streets and houses of to-day. Our first illustration [fig. 1] shows the plan and section of a street in Paris of average importance. It does not differ, except in details of secondary importance, from any street in any other European city.

On one side I have given a drawing of a house dating from the last century, and opposite to it I have placed one of modern construction.

I shall not stop to criticise the former; the arrangements are inconvenient, and the sanitary provisions deplorable. I have reproduced it here solely for the purpose of exhibiting the contrast between it and an up-to-date dwelling-house, and to emphasise the great progress that has been made. Yet even the latter leaves very much to be desired. True, the modern house is furnished with lift, water, gas, electricity, telephone, bathrooms, and a complete system of drainage; but at the same time we find that it includes ridiculous chimneystacks which discharge volumes of unwholesome smoke over the town. The removal of ashes and of every sort of refuse is carried out in a most barbarian fashion by means of filthy bins, which are deposited every night along the pavements and in the morning are emptied by the dust-carts. As to the actual cleansing of the dwellings, it is of a still more rudimentary character. The process consists of opening the casements, sweeping the floors, and then beating and shaking the mats out of the windows, so that all the dust, and all the germs, are liberally scattered through the atmosphere which is being inhaled by the passers-by.

Of these units, the house and the street, the latter has received the smaller number of those improvements which might have been effected at once. The modern street is the ultimate form of the old country lane, formerly a track-way in the natural soil, subsequently paved and bordered with footpaths.

Underneath the roadway, in the soil itself, a sewer was constructed, its original function being to carry off the rain and waste waters; but later on it was used for a variety of other purposes for which it was never intended. The first of these was the laying of mains for pure and river waters. Then tubes for pneumatically conveyed messages were added, with pipes for compressed air. Finally this sewer, or passage way, was employed for the telephone and telegraph wires, a system which grew daily more extensive and more complicated Such a conduit, already too much congested, was incapable of receiving the cables for the supply of electric light, and it became necessary to form other conduits beneath the footways to receive the wires, these conduits being placed deeper in the soil where otherwise they would be in close proximity to the gas mains. All these pipes and tubes are located above or beside one another, without order or method. When they have to be repaired, each system, whether it belongs to a private company or to one of the departments of the Administration, has to be dealt with separately, without any co-operative plan, and as occasion arises. It is because of this that, for the last ten years (I am speaking of Paris) the city has been in a constant state of upheaval, and vehicular and pedestrian traffic has become more and more difficult.

These works have all been attended with the most unfortunate results with regard to the street itself. The continual disturbance of the soil has had a detrimental effect upon its compactness, and it therefore becomes necessary to lay down a temporary pavement and to wait several weeks until the soil has settled sufficiently to permit the relaying of the permanent paving--unless, in the meantime, a new branch of the Metropolitan Railway necessitates a new upheaval from top to bottom.

The most serious drawback in this system is that it renders it very difficult, not to say impossible, for any industrial concern to introduce any new element conducive to the health and comfort of the inhabitants: and yet we may already easily foresee what some of these elements are likely to be. It is pretty certain, for instance, that vacuum cleaning will become general, and that a system of pneumatic pipes will soon be required for the extraction and destruction of dust, to the incalculable benefit of the public health. These conduits, which must necessarily be very extensive, cannot be placed in the sewers.

The conveyance of letters by pneumatic tubes, larger but otherwise similar to those now used for despatching messages, will also become necessary, from the standpoint of both economy and speedy transmission.

The services to which refrigeration is put are multiplying, and there is nothing absurd in prophesying the necessity for a network of pipes for liquid air. Coal is a fuel suitable for factories only, for it is both cumbersome and dirty. We can therefore assume that, in the future, petrol will be supplied from house to house through pipes, thus conveying everywhere, and without dirt, a more convenient fuel.

Oxygen combined with petroleum would supply an intense heat, without smoke, for steam heating bakers' ovens, &c.

We may also imagine other special mains for the distribution of sea-water and pure air, conveyed either from an islet near the coast or from the top of a mountain. As such air may only have to be supplied to congested districts, or to special inhalation-rooms, my view may appear somewhat overdrawn; but, nevertheless, I wish to mention it by way of illustration and to show the possible development of installations of this kind which further scientific discoveries may call into existence.

In order to render such progress possible the streets would have to be constantly and periodically interfered with, at a cost that would be prohibitive to the companies undertaking the work.

If we wish to find a remedy for such a state of things we must approach the problem in all its bearings, and ascertain what would be the best plan to adopt in laying out a new city, or at any rate a new quarter, which is to be constructed in accordance with a general scheme. We shall see later on how it would be possible to apply our conclusions to the transformation of cities already in existence.

All the evil arises from the old traditional idea that "the bottom of the road must be on a level with the ground in its original condition." But there is nothing to justify such an erroneous view. As a matter of fact, if we were to establish as a first principle the idea that "the pavement and carriage-way must be artificially constructed at a sufficient height to allow thereunder a space capable of containing all the installations needed for the service of the road," the difficulties I have just pointed out would disappear altogether. This, of course, implies an additional floor underground for the neighbouring houses, inasmuch as the ground floor would thus be raised to the level of the street.

The illustration [fig. 2], shows the plan and section of a road constructed in accordance with this new conception. This view brings out clearly the advantages thus obtained. In the first place the pavement and the carriage-way would be constructed once for all like a bridge roadway, and ought never to be interfered with in any way except for the purpose of upkeep and repairs. The paving, either of wood or any other elastic material, would cover a monolithic platform of armoured-concrete. This platform, constructed at a height of 5 metres above the ground proper, would rest laterally upon two walls of masonry, parallel with the walls of the buildings fronting the road, from which they would be separated by a small space. Between the lateral walls the platform would be supported by several rows of pillars, with spaces between them of about 4 or; metres.

Immediately below the bridge roadway would be suspended the whole system of pipes required for the purposes we have just enumerated--viz. vacuum cleaning, supply of compressed air, river water, sterilized pure water, petrol and liquid air; conveyance of letters; supply of pure air, &c.; together with all the network of electric cables (telegraph, telephone, light, power, high-frequency currents, &c.

Underneath the said systems, which would all be easily accessible and controllable, a space of 2.25 metres in height would be left entirely free and extending down to the ground-level. Four lines of railway would then be laid, one metre apart, upon which would run trains of small trucks for the removal of all rubbish and refuse, as and when required, for the conveyance of all heavy and cumbersome materials, and to clear the rubbish from building or repairing yards.

The two central lines would serve for long-distance transports, whilst the two lateral lines would be used for making up the trains; they would be connected by turn-tables to the private lines leading into the houses. Each opening through which the trucks would enter the cellars would be closed by two independent doors or iron gratings in such manner that any communication between the house and the service road would be impossible without the simultaneous permission of both the owner's agent and the representative of the administrative authorities.

This underground street would be lit permanently by incandescent lamps and glass plates on a level with the pavement. Natural ventilation, assisted by electric fans, would be ensured by high chimneys located at given intervals in the party-walls between the houses.

Each frontage would, at the base-line, be separated from the next by a regulation recess of 2 metres by 1, within which would be located the ventilation flue. This arrangement would greatly improve the architectural aspect of the frontages, which would thus be sharply divided from one another.

Below the natural level of the service road would be laid, as now, the sewer, but its dimensions could be reduced, inasmuch as it would be exclusively used for the carrying of the water: drainage by gravitation could perhaps be replaced by large watertight mains to receive the waste water, which might either be forced out or sucked up without regard to the level of the ground.

Finally, in the centre of the service road a large fireproof main would be laid underground for the conveyance of smoke, assuming that the old-fashioned method of heating with wood or- coal were still in use in a few houses, although it is to be hoped that smoke producing chimneys will then be prohibited and replaced by oxygen stoves, permitting complete combustion.

In any case, this main could be retained for exhausting the gases emitted by kitchen stoves.

To sum up: this arrangement really means that the present street would be made into two streets: one above in the open air, solely intended for the passage of light vehicular and pedestrian traffic, and the other located below, on a level with the ground and underneath the former, which would serve as a conduit for all the pipe systems, the removal of house refuse, and the transport of heavy materials and goods.

We may mention the traffic tunnels in Chicago between the railway stations and from private depots as being somewhat of this nature: but these subways are attended with the twofold drawback of being located at too great a depth and of being much narrower than the street. A flat platform occupying the whole width of the street is far preferable, notwithstanding its many points of support, to a vaulted subway, because it utilises all the space available.

Supposing even that the requirements of new installations should call for more room, or that the construction of a new line of transport should become necessary, it would be possible to dig deeper to obtain the space required, underpinning the points of support; and any number of subterranean floors could be provided without in any way touching, congesting, or interfering with the traffic of the upper roadway.

By the expansion of such a plan we are led to conceive of a city in which all the streets with heavy traffic would have--according to the frequency of the traffic--three or four superimposed platforms. The first platform would be for pedestrians and carriages, the second for the tramways, the third for the various mains and pipes required for the removal of refuse, and the fourth for the transport of goods, &c. We should thus have a many-storied street, as we have a many storied house; and the general problem of traffic could be solved, however heavy it might be [fig. 3]. It is probable, however, that the duplicate streets I have just described would suffice, at least for a very long time, under the present conditions of urban life.

The adoption of such a plan would be easy in a new town. At the end of the system of roads first constructed, in order to establish a direct communication with the natural level of the land, gradients would be constructed with a rise of 5 per cent., supported by iron frames capable of being taken to pieces and removed to a greater distance when the expansion of the town rendered it necessary.

With regard to the earth excavated from the foundations of houses and other buildings, instead of being conveyed at a great expense outside the town to encumber the surrounding country with rubbish heaps, this would be utilised for raising the ground-level in those parts of the town where underground streets would not be required, and in laying out parks, gardens, or public squares, which it might be desired afterwards to form. In fact it is the relative proportion between the potential quantities of excavation and filling-in which would determine the height above the ground-level to be adopted for the artificial roadway.

The application of such a system to existing towns would be more difficult. The problem in this case would be the removal of large masses of earth for the purpose of excavating the lower streets, for there could be no question whatever of removing our art treasures or of interfering with our historic monuments and the time-honoured aspect of our ancient cities. Yet this is not impossible in itself. It is merely a question of money, and the amount can be calculated. Based upon a gross estimate, including the removal of earth up to 5 metres in depth, the construction of the platform and of the sewers of the lower street, the cost works out at 140 fr. per square metre (exclusive of the various mains and electric cables, the cost of which would have to be borne by the lessee companies).

The area of the public roads in Paris (roadways and pavements) being about 1,500 hectares, the total cost would come to two thousand one hundred millions of francs (£84,000,000). On the assumption that the execution of the work would be spread over a period of 100 years, the annual cost would amount to 21,000,000 francs (£840,000), which would not be exorbitant in an annual budget of 350,000,000 francs (£14,000,000), But the whole heart of Paris, i.e. one-third of its total surface could be transformed in thirty-five years at a cost of 700,000,000 francs (£28,000,000)

In any case, the point to be remembered in this examination is that every new road opened in an old town should in view of what the future may bring. be constructed on the principle of a double roadway.

Let us now consider the buildings fronting these streets. The adoption of the new industrial devices, previously described, would make it possible to ameliorate the conditions of modern life and to add to the health and comfort of the inhabitants. I shall not dwell upon the improvements already effected and applied in some modern houses; they are shown in the illustration [fig. 2 p 349]. By these means, side by side with lifts for people we shall find an elevator going down to the cellars for heavy weights, and movable boxes for the conveyance of letters and parcels to all floors; we shall find the bath and douche rooms accompanied by hydro-therapeutic sea-water chambers; while together with a complete system of drainage for waste water we shall also have a system of vacuum cleaning for light dust, and the special discharge-hoppers in each flat for the removal of refuse, which will descend and accumulate directly in the small trucks in the underground street.

Light and energy will be conveyed by electricity. Petrol and oxygen will supply heat. Liquid air will be supplied to refrigerators in every larder for the preservation of eatables. In addition to heat radiators we shall also have cold radiators, which will enable us readily to maintain in each house, in all seasons, such temperature as may be determined upon. Finally, the power given us of varying, as desired, the temperature, density, and quality of the air inhaled as well as the ambient electric waves, would enable us to provide in each flat one or more health chambers, closed by tight-fitting double windows and doors, in which the householder, exhausted by the stress of city life would always find an atmosphere and surroundings suited to his own health or to that of his family, with all those hygienic requirements which he is compelled each year to seek much further afield, and which, even then, he can only enjoy for a limited period. Do not let us forget that a cubic metre of air drawn from a much-frequented street--say, for instance, the Rue de Rivoli--contains six thousand germs, while a cubic metre of pure air on the open sea or in the mountains contains but two or three. As to the chimneys with their clouds of unhealthy smoke, they would be completely done away with.

Glass verandahs of various shapes, but connected in accordance with a definite system, would extend over the full width of the footpaths, and would shelter pedestrians from the rain.

The normal height of the buildings would be exactly equal to the width of the street, so that the angle of incidence of the light falling upon the frontages would not be less than 45. Each proprietor, however, would have the right to construct a tower or a raised belvedere in such part of the front of his house as he may choose, subject to the width of such structure not exceeding one-quarter or one-third of the total width of the frontage.

This right would be granted for the double purpose of allowing greater variety in the architectural treatment of the elevations and to facilitate the installation of wireless telegraphy.

The system adopted at the present day for roofing our city dwellings is open to very great objections. It is based upon an old idea which, though once sufficiently reasonable, is now no longer capable of justification. It is one of the most striking instances of the illogical conclusions to which a deep-rooted habit may lead, that such a system should continue in use side by side with new methods of construction which ought long ago to have caused it to be discarded. We build up our walls with excellent materials--such as freestone, sandstone, brick, and similar substances--and we use cements of the highest quality to bind them together; with the result that our vertical work is so strong that it defies the destructive agents contained in the atmosphere and has a durability which is practically unlimited. This structure we proceed to cover with a roof made of flimsy and perishable materials--wood, slate, thin sheets of zinc, and suchlike--with an average life which does not exceed forty years, and entails repairs that, at one and the same time, are constant, unceasing, and costly. The only buildings of the ancients, such as Agrippa's Pantheon, which have preserved their coverings down to our own days are those which were provided with roofs constructed of great blocks of masonry and of concrete. Light and inexpensive roofs laid at a greater or less slope are admirably adapted for factories and for houses situated in the open country, where the buildings are scattered and the land values low: but in populous cities the flat roof is becoming more and more imperative. It has the twofold advantage of being exceedingly durable while at the same time it brings an area equal to the area of the whole house into useful service.- With all the varied advantages which the employment of armoured cement offers, the covering-in of our houses with a level platform has become a simple matter, and this platform could be planted with small flower gardens or adorned with verdure clad trellises.

But a still more important function to be performed by these terraces is that in the near future they will be used as landing stages for aeroplanes. We have not as yet arrived at that point because up to the present the aviator has not gained sufficient mastery over his machine: but as man has at length succeeded in imitating the flight of the bird it is by no means improbable that he will eventually succeed in imitating the flight of the insect. In "The War in the Air," Wells has imagined a small, handy machine, easily controlled and guided, built somewhat on the principle of the bee. I do not think I could adduce any higher authority on the subject, and without hesitation I accept this very attractive forecast. We may, I think, imagine some form of light aeroplane, equipped with horizontal helices in addition to the vertical propeller, and capable of remaining stationary in the air, hovering over a given point even as the bee first hovers above the flower on which it is about to settle.

When this result has been achieved the aspect of our cities will be changed; for every terrace will become a stopping-place for these aerial automobiles. We shall be able to alight upon terrace after terrace and take wing once more at will. This possibility will bring with it the necessity for a very large lift in every house, of sufficient capacity to raise the flying machine when ready for its journey and to convey it back to the garage on its return. These lifts would be similarly employed for carrying motor-driven vehicles to and from their garages. The raising of the courtyard, resulting from the raising of the street-level, would allow sufficient space underground for all the necessary garages. All these different arrangements are shown in the illustration [fig. 2, p. 349].

At this point we are brought face to face with a very grave problem which, while resulting from the movements of aeroplanes over our cities, affects the safety of the inhabitants. It is obvious that if a motor weighing some hundreds of pounds were to fall from a height of two or three hundred metres on to the roof of a house the consequences would be disastrous: if the accident occurred over a museum it is to be feared that the irretrievable destruction of valuable objects would be the result. It may be hoped, however, that before long flying machines will be fitted with automatic parachutes, minimising the danger; and, if the truth be told, the risk to passers-by would hardly be greater than that to which they are now exposed by passing motor-cars, while in the case of buildings the risk would not be greater than the exciting perils of fire, lightning, or gas explosions. In any case, even when the risk is reduced to the minimum it will still continue to be a risk; and it will be greater in proportion to the weight of the flying machine itself. We shall, therefore, be. compelled to divide these machines into two categories, the lighter aeroplanes of the bee-type and the heavier aeroplanes of the bird-type, with which latter would be classed dirigible balloons: and unless we wish to go back to prehistoric days when troglodytic man lived in caves and in shelters cut out of the sides of cliffs; unless our terraces are to be protected by the same armour-plating as that in which our ships of war are encased--we shall certainly be compelled to create an aerial police force and to draw up stringent regulations which shall control the movements of all flying machines.

Perhaps it may be found necessary, even in the open country, to mark out the great high-roads of the air by means of air-buoys which would take the form of captive balloons. As regards the cities, they will probably have to be subdivided into three sections. The first, consisting of the heart of the city, would include the principal buildings, historic monuments, museums, theatres, &c. No flying machine of any kind whatsoever would be allowed to fly or to "plane" above this section of the city. The second section would consist of all such portions of the city as are built over with houses and other erections of a modern type, with terrace roofs of sufficient strength to bear without injury the fall of a light aeroplane. Over this section only aeroplanes of the bee-type would he allowed to fly. The third section, accessible to all machines would contain the landing stages for large aeroplanes of the bird-type and for all heavy machines.

One of the facts brought into prominence by the trial flights made in the eastern part of France during August of this year was that there was a great lack of landmarks such as might assist the aviator in keeping to a desired course, especially during misty weather: and it was found that the steeples of the churches and cathedrals were more valuable than anything else in helping him to keep in the desired direction. Here we have a very valuable indication of what should be done. It will soon become imperative for every important community to erect landmarks in the form of lofty towers or soaring steeples of unmistakable character; and these at night would have to be furnished at their summit with beacon lights.

The small towns might remain content with their ancient belfries; cities of average size would be obliged to erect towers of a hundred to a hundred and fifty metres in height: as to the great capital cities, such as London or Paris, Berlin or New York, towers of three hundred metres in height would not be sufficient, and their summits would have to attain an altitude of at least five hundred metres. These colossal erections would serve at the same time as stations for wireless telegraphy; and it is scarcely too bold a thing to predict that, by means of these great landmarks of the terrestrial globe, communications could be exchanged instantaneously between all the countries of the world.

The necessity for establishing these lofty landmarks opens up splendid dreams of the aesthetic appearance that would be imparted to the great Cities of the Future. In them our successors will find a wealth of artistic possibilities when the time comes for them to erect their towers, which they will adorn with decorative sculpture, with modelled terra-cotta, and with ornaments of bronze and gold.

Having set out the hypothetical data, let us now endeavour to form a general idea of the great Cities of the Future. The illustration here given [fig. 4] is but a hasty and incomplete sketch, but your own imagination will enable each one of you to fill in the picture according to your individual conception of the matter.

From out the centre of the city's heart there will arise the colossal orientation tower, soaring to a height of five hundred metres, and crowned by a powerful beacon light. At the base of the tower the historical portion of the city will nestle, with its monuments of bygone days, its old houses, and all its artistic and traditional treasures.

Around this there will be a girdle of great towers--each one from two hundred and fifty to three hundred metres in height--to warn off aviators from the forbidden area. These erections, each of a very different form and readily to be distinguished the one from the other, might be eight in number and placed at the cardinal points of the compass. Beyond them would come an annular zone of flat-roofed houses, this zone measuring from two to three kilometres in width: and above it aeroplanes of the bee-type would be permitted to float from terrace to terrace. At the circumference of this area a second girdle, consisting of tall standards or metallic poles of a hundred and fifty to two hundred metres in height, will mark the limits of the city, and will serve to warn off the greater airships. These standards, with their crow's-nest summits, will serve as observation stations, whence an unceasing look-out will be maintained by members of the aerial police force; each of whom, mounted on his light aeroplane, will be ready when occasion arises to prevent heavy machines from flying over the city, Beyond the ring of standards will be situated the great Landing stages which will constitute the termini of all the aerial high-roads. Still further afield there will be the enormous power stations required for the public service.

The city as a whole will be traversed by wide roads radiating from the centre, and partly occupied by elevated platforms kept continually in motion, so that by this means rapid intercommunication between the several zones will be assured. These platforms will be terminated by revolving turn-tables, erected over the point of intersection of the principal streets. Lastly, the city will be planted with large parks and flower gardens, forming centres wherein rest, health, and beauty may each-be pursued.

To bring these dreams within the range of-practical possibilities would require the expenditure of enormous sums, and it is for this reason that the carrying out of such a project must be relegated to some date within the far-distant future.

Nevertheless, the far-reaching revolution brought about in our ideas by aviation opens up such wonderful possibilities that we may indulge the hope that all these things will come to pass. The conquest of the air will herald the reign of universal peace and wealth. The Cities of To-morrow will be more readily susceptible to transformation and adornment than the Cities of Yesterday: they will be built with superb towers which will attract these giant birds from every point of the horizon: and before long, perhaps, our great capital cities will raise their beacons to a higher and yet higher altitude, competing with the very clouds themselves. 

Selected, scanned, edited, provided with headnotes, and formatted as a web document by John W. Reps, Professor Emeritus, Department of City and Regional Planning, West Sibley Hall, Cornell University, Ithaca, New York 14853, USA. Tel: (607) 255-5391, Fax: (607) 255-6681, E-mail: 
To Top of Page
To Homepage