A viaduct in Paris

December 8, 2011

This post is not about the viaduc des arts and its promenade plantée which has been the object of a previous post. While Vancouver is thinking that destroying its viaduct structures is forward thinking, and some even suggest that this tabula rasa thinking is at the root of good urbanism…Paris is building more viaducts…

The Parisian Viaduct:

Avenue pierre mendes France, in Paris: It is a viaduct! 40 meters wide and streescape structure similar to Pacific Boulevard at Davie (Vancouver BC)... (credit photo, wikipedia)

The “Avenue Pierre Mendès France” viaduct, built between 1995 and 2001 (general conception by Paul Andreu) is one of the most recent addition to the Paris grid, in the new “rive gauche” district. You will notice, that well proven urban concepts have been applied, be in the building form lining the viaduct, the rectitude of the street, or the streescape…One will eventually find the result to be more convincing that on Pacific Boulevard (Vancouver) of similar width, and that is eventually the reason why you see people in the median which has its own name:

  • promenade Jules-Isaac

Which says enough of the objective filled by this avenue. Notice also how only one lane of general traffic per direction is offered, and how the bike lane is implemented in the median (in my opinion the best solution).

Under the viaduct

No painted blue sky here! railtrack and their platform (under construction) doesn't prevent to neglect the experience under the viaduct. credit photo (1).

In this case, the required right of way has necessarily constrained the piles disposition, but it is in fact a general Parisian style piles disposition we find in most, if not all of the city metro viaducts which allow an exploitation of the underneath space in both direction (you can see, how advantageous it can be under Vancouver’s Cambie bridge South side)

Beside the viaduct (or almost)

It is the jardin Abbe Pierre, opened in 2009, which is supposed to filter StormWater before letting them running directly into the Seine river.

the Abbe Pierre garden is below the "street" level credit photo (2)

Elevated view point on park and garden has been a common feature of the “jardin à la française“, but the relatively new sunken garden trend offers some attractive features:

  • It provides a sense of intimacy, by “removing” you of the rest of the city
  • It tends to be away of the street noise propagation pathes

In the case of the abbé Pierre garden, the artificial elevation of the street provides a pretext for the sunken garden…It is a nature garden, designed to filter storm water, and feature a swamp, as well as an insectarium to support the eco-system.

The example also apply a rule of thumb.

  • If a space under a structure is not usable, close it to the public!

The Vancouver viaducts

Thought the idea to treat the viaduct as a street is not new, and find some ground at the edge of the Dunsmuir and Georgia viaduct, as well as Granville Bridge: Paris could have still one thing or two to teach to Vancouver, especially when come to talk about viaducts on a bigger scale…

Lot of proposal have found inspiration in the promenade plantée (or the New York High Line) including the winning entry 71, in the recent Vancouver viaduct competition, but curiously enough, the unfortunate entry 109 was one of the only one, to consider the viaduct streetwise [3]:

In those Dunsmuir viaduct views, the viaduct is treated as a "street/promenade" stitched with premises, and still open enough to provide vantage points (the skytrain track provides also some challenge, but which can be addressed relatively well


[1] http://www.capremib.com

[2] http://paris.foxoo.com

[3] entry 7titled “make it a street” mentioned the idea but more by raising the rest of the grid to the viaduct level

The Viaducts Competition

December 5, 2011

This post refers to the Vancouver viaduct competition occurred in November 2011

Death to the viaducts is the jury sentence. The winner of both the jury and People choice, stealing the spotlights, is the entry 71:

The best we can do according to the jury and Public which have given a plebiscite to entry 71

The Jury, adverses to any viaduct views, choose some other entries which if not eliminating the viaduct like 71, or building a crypt to its remnants (nice attention from entry 113), was either burrying them-and all the local street network-under a huge tumulus segregating the historic precinct of False Creek (entry 111), or hidding it away in an canvas like composition, seen from an improbable point from the sky (entry 72), or not showing at all what could be done with them or their land (entry 138) – N.B. the goal of the competition was to “visualize the viaducts or the land they occupied” … The only rewarded entry showing a viaduct is the entry 72:

The Jury has been thrilled by how the space below the viaduct has been made more engaging by entry 72. Beside the Banksy's Graffiti, notice also how this entry seeks to negate the viaducts structure by a kind of Magritte style treatment of it

An unsuccesful entry

Entry 109 , focusing more at removing the barrier effect, than the viaduct themselves- the real physical barrier being obviously the Skytrain guideway-reflects my previously stated position on the viaducts.


a bird view of the site as proposed by entry 109

Entry 109 put the traffic (“blood” of the city) front and center, and emphasis on the following values:

  • Reconnect Chinatown to the rest of the urban Fabric
  • Currently Chinatown is cut from the rest of the city, West by the Andy Livingstone park, and South by the bridges (as well as Thornton park and the Skytrain viaduct…it is simply too much of urban discontinuity to invite people to Chinatown), the entry suggests building lined streets along Keefer and more importantly Main. That motivates the removal of the Main overpass.

  • Open Gastown and Chinatown to the False Creek shore
  • The entry introduces a canal in the Carral street axis to that purpose (then people can go straight toward the shore, passing below the skytrain guideway, along the Canal). other North/South streets are extended up to pacific Boulevard.

  • And more generally, keep the seawall open to the city by locating the development on the edge of the site
  • rather than along the shore

  • …and respect the View cone policy
  • In the case of the viaducts area, the view cone policy mainly protects perspectives from South East False Creek which also can help to prevent a disastrous “toilet bowl” effect on the False creek basin

  • Develop Georgia street as a “ceremonial” street ending on the false creek basin in the Science world axis.
  • That certainly motivates the removal of the Georgia viaduct, if you want Georgia street to be an urban boulevard with traffic going down to Pacific Street what is advisable to preserve its urban feel

  • Provide a pleasant urban street feeling basically everywhere
  • That motivates a realignment of the Expo boulevard, to enable it to be lined by building on its south side rather than to be defined by the Skytrain guideway, avoiding the problem seen on Lougheed Boulevard in Burnaby or Number 3 road in Richmond.

  • Don’t compromise East West connection

There is no clear motivation to remove the Dunsmuir viaduct. From an urban viewpoint it basically adds nothing, since you are still left with the Skytrain guideway barrier, and eventually have even a negative outcome, since you end up to have at best a very clumsy landing of Dunsmuir somwehere either on Expo or Pacific boulevard, (which also end-up to relocate the viaduct structure more than removing it)…or worst, a dead end Dunsmuir street accompanied by a lost of a gentle grade access to downtown. At the end you have to consider the positive side of a viaduct asset: it can be seen as a balcony on the “urban theatre” as described in the entry 109…and a treatment of this asset under this light is suggested in this entry.

Unfortunately, the values expressed by entry 109 were not shared by the jury which had another motivation in mind.

A provocative idea I should have eventually submitted: "it is not the viaducts we should bury !" The picture speaks enough of an efficient use of landscape freeing prime real estate at Mountain View.

A Viaduct too far

April 12, 2011

It was a forum on the viaduct removal on April 7th at SFU downtown. You will find on pricetag a list of links on it including one to the good report of the night by Stephen Rees. We gonna mostly refer to it to review some arguments mostly developped by Larry Beasley, but also Bing thom

The viaducts impede real estate development

Growth will have to be accommodated here to relieve pressure on Chinatown and the downtown eastside

there is several flaws with this argumentation; also used, as an answer to Ned Jacobs, to explain the lack of affordable housing in Vancouver:

  • Do you believe that Coal harbour and Yaletown development has relieved pressure on the westend?

But mostly, the argument rely on the theory of “ghost acreage”: that is, you are always looking for new land to accommodate your current need, because you claim you can’t do it within the given land you already have.

  • not only that is not sustainable in the long term, but the argument could be used as well to support the abolishment of urban containment boundary and obviously the ALR !

But really, do you believe that the viaducts impede real estate development?

Thought the viaducts create some undeniable constraints for developers, which could not like them too much- since it forces them to be a bit more creative than usual- it doesn’t prevent application like the one city for Vancouver has for 800 Griffiths Way

rendering of a development application for 800 Griffith Way. Not only the viaduct doesn't prevent development, but could allow Vancouverites to experiment different urban experience, pretty much like the dramatic arrival to Toronto thru the Gardiner expressway...as suggested by the right rendering,

the 800 Griffith way Application let suggest that the removal of viaducts could not help too much to increase the buildable area, since buildings need some access to light anyway.

Let’s replace them by a “world class” boulevard
…and have an international competition to do that….

Well, the first problem is that the removal of the viaducts transform our existing boulevards, Dunsmuir and more importantly the ceremonial Georgia street in cul de sac…

  • What is the deal with that?

That sound pretty much as robbing Peter to pay Paul

  • why we should believe we gonna have on false creek what we have failed to see materialized in other part of the city?
  • what Larry Beasley think of? Pacific boulevard in yaletown version 2.0 ?

The second problem is that, there is no lack of actual opportunities for brainstorming on “boulevard” experience toward the improvement of numerous toroughfare in town, among them, Broadway, Main, and certainly more importantly Hasting in dare needs of a treatment…

  • Why we don’t use them to showcase the field of possibilities?

The traffic issue

The modelling of traffic in case of the viaducts closure is not so encouraging…Panelists as well as some contributors from the audience have casted doubt on the traffic model…and eventually some wrong interpretation has been drawn from the Cheongyecheon freeway removal in that instance. To put some perspective on it, below a verbatim of what Dr. Kee Yeon Hwang had to say to the Translink Buzzer blog:

we had three tunnels linking the southern part of Seoul to downtown, and one was due to be shut down for some mending. Someone asked me to make a simulation to see what would happened, and I ran my model and saw some very strange things. Once we closed the tunnel, we saw some areas of the downtown traffic improved. And then construction started, and we found the simulation almost came true in reality. I saw that many links encourages more routes. Once we got rid of some roads, that might reduce people’s willingness to travel downtown by car. Cheonggyecheon stream came to the same result…[]…We came up with a very nice result that if it was demolished, traffic congestion would not be so severe

  • In Seoul, removing of the Cheonggycheon freeway has been made possible by positive outcome of traffic model, which has proved to be accurate enough.
  • In New York City, pedestrianization of Times square has been almost justified by positive outcome of traffic model, which has proved to be accurate enough.

If clearly, some lessons of the Cheonggycheon freeway removal are not well learnt in the region, there is apriori no reason to believe that traffic engineers in Vancouver; able to use the experience of the Olyimpic game, as well as the unexpected closure of Pattullo bridge are less equipped and competent than their colleagues from New York or Seoul. If the traffic model announces an unfortunate outcome consecutive to the closure of the viaducts in Vancouver:

  • Ditching the traffic model seems to be a pretty shallow answer

It is not much surprising in fact. As illustrated in my previous post , there is lot of unused road access capacity in Vancouver; hence there is apriori little reason to believe that the removal of the viaduct will translate in public transit shift if there is no change in the offer of it and much more to believe this traffic will be redirected on other boulevard like Hasting.

In addition, when you consider that the redirection of traffic to hasting and Pender will impede the effectiveness of the transit on those avenues, there is even less reason to switch to transit

  • Couldn’t be a better option to reduce traffic on, eventually by integrating a tram on it, rather than fueling more traffic on it
  • Couldn’t be a better option to beautify Hasting? Does the removal of the viaducts will not compromise it?

Hasting street badly needs an urban renewal treatment. Should it be a motor vehicle thoroughfare, or designed toward softer transportation mode: does the removal of the viaducts will allow the later choice? credit photo left CBC

The viaducts cut off Gastown, the DTES, and Chinatown from the False Creek waterfront.

  • If so what about the Skytrain one?

The problem with this argumentation is that those communities have never been connected to False creek. Georgia viaduct has existed-albeit, under a different form- since 1915, and was rather connecting communities anyway cut off water by rail yard…and before by marshes. We can certainly argue otherwise

  • why the Georgia and Dunsmuir viaduct and not the Skytrain one?
  • Removing the viaduct will severe potential connection from strathcona and Mount Pleasant to “upper” downtown (Georgia and Robson area)

We are not in the case of a viaduct cutting off a community of its “raison d’etre” or roots like often seen, as in the case of the Cheonggyecheon freeway in Seoul, or in least extend in Seattle with the Alaskan way or former Embarcadero Freeway in San Francisco…We don’t have a double stacked freeway to deal with too!

… but really, does there is no way to accommodate connection of neighborood with the waterfront?

the celebrated 'promenade des anglais' in Nice, pronged by the quai des Etats Unis, is separated of the historic city by a double 'wall' of now decommissioned elevated promenade. This 'cut-off' doesn't prevent Nice to be a 'world class' beach resort renamed for its waterfront promenade. Indeed that has allowed the historic neighborrod to preserve and develop its distinct identity. credit photo left wikipedia, right (1)

The Hogan Alley memories

The construction of the viaducts, or rather the overpass on Main street has induced the destruction of the Hogan alley, and this fact has been brought back apropos by noone else than Ned Jacobs himself, whose has suggested an Hogan Alley Planing Initiative (HAPI). We understand it could be strongly community driven with great emphasis on affordable housing. Hard to disagree with that! That said, the reading of some other blogs invite me to remind some context here:

Thought that the urban legend could let the general public believe that the viaducts has bleed a whole neighborhood, Hogan alley was in fact referring to a block delimited by Union and Prior, Gore and Main… the only block destroyed.

Hogan Alley is in fact the alley in the middle of the block delimited by Prior, Union, Gore and Main. credit Photo, City of Vancouver

  • It is hard to fathom why the current community would like lost its now green space to revive some vision based on an idealized past and distorted view of the history of the neighborhood

The locus of this community was the Fountain Chapel church which was founded by Nora Hendrix, whose happen to be the grand ma of famous guitarist Jimi Hendrix. The church still stand there. Ironically, at the time to write this post, the church is on the market, asking price is $1.450 millions , but no worry…the lot is zoned RT-3, that you can convert it in luxury lofts with soaring ceiling.

The last remnant, and may be most significant one pertinent to the Hogan alley community, is on the 'chopping block' who cares?. credit photo wikipedia

  • People are all up in arm on the supposed scare of the viaduct on Hogan alley…but the last and may be most significant remnant of a disappeared community is on the chopping block and no-one cares?

In Conclusion

As I have already expressed on the Gordon Price’s blog, in the evening, I have heard ‘removal’ of structure and other ‘negative’ words …but what positive outcome?

  • what we, as people can gain from the removal of the viaducts?

I didn’t heard a single argument justifying the removal of the viaducts since all the goals advanced can be accomodated with the viaducts. In fact the viaduct removal option seems driven only by an ideological “war on car”, justified by argument not able to hold much water. That is a problem and a question need to be answered

  • what you can’t achieve with the viaducts in place?

As long as you don’t answer in a compelling manner to this question, the removal of the viaduct will be seen as a direct and gratuitous attack to the ‘motordom’ with great chance to be lost, with as unfortunate consequence the probably stalling of more reasonable efforts at curbing the occupation of public space by the automobiles.

Eric Doherty was spot-on when noticing that while we are devising on the fate of a rather inoffensive viaducts, the whole region is besieged by road builders. Energy could be more usefully used at preventing damage than to focus on the destruction of an iconic structure

That said, Peter Judd like Larry Beasley and other panel members are right: we need a vision for the future of the viaducts land…But we need the vision first, be this vision integrate the viaducts or removing them partially or totally…

if so, it will be then time to discuss of the viaducts fate…that is the right order of the thing, not the other way around as like currently engaged


To show an example, and to capitalize on Bing Thom exhortation to citizen to get involved, here after is my modest vision

A Vision: The Skywalk over the marshes
…and among the pile dwellings

In 1898, most of the False creek flat was still inter tidal water, especially at the actual location of the viaducts. It was still a False creek spur going under Georgia viaduct until 1964, illustrated by the left picture taken circa 1939 (Collection of the city of Vancouver)

Like the Cheonggye stream was there at the origin of Seoul, the viaducts land was originally an inter tidal marsh which was still partially existing at the time of the construction first Georgia viaduct. and here are some assessment:

  • inter tidal marshes are key ecological systems, and disappearing very fast, we need to do something to counter this trend
  • The sea wall offers a very nice promenade, but it is a “wall” between water and land, preventing inter tidal life where it has naturally existed

Great extend of false creek was inter tidal marshes, and it is time to lead by example, this by restoring those keys ecological system, and the viaducts land provides the opportunity to do it.

The viaducts, part of the Vancouver history since 1915 get a renewed “raison d’etre” in addition to address the escarpment at Beatty street.

Like noted by Jan Gehl [3], human eyes vision is more developed downward than upward, and it can be a reason why people like to gain elevation to appreciate vista. The viaducts provide it and multiply vantage point on False creek.

  • beautify them and increase pedestrian space on it (remove one lane of traffic on Georgia)
  • add some mezzanines, for benches; why not some restaurant with patio accessible from the viaduct providing great view on the creek
  • Play on the vertical space by adding some connection with the ground appropriate to the human scale

The vision justified by the original landscape, combine a pedestrian friendly viaduct offering a promenade providing elevated vantage point on False Creek. The viaducts are themselves built over a restored inter tidal marsh. credit photo (2)

The marshes should be accessible to people by a system of trail bike path one of them running under the viaduct for those days we wish to be protected from weather element.

Access to Downtown thru a bridge or viaduct is part fo the vision, since it allows to reinforce the peninsula nature of Down Town. For sure it prevent the sprawling of it, but it is eventually the very reason we have an attractive and dense down town, and are able to develop secondary neighborood like Kitsilano, Mount Pleasant, Strathcona with their own identity worth to be preserved by keeping or restoring natural barriers.

The vision doesn’t prevent development, but capitalize on the “root” of the area, the existing structure, to provide a different experience to Vancouver while still true to what should be the very nature of Vancouver which is to live in symbiosis and respect of its surrounding environment.

building anchored on pilotis soar above the marshes...and the viaducts too. legend photo left (4), right (5)

The picture could not be complete without the restoration of the canal to Chinatown, ideally up to keefer street, providing a link from this community to the Waterfront, inviting to calm and relaxation.


[1]http://www.formule4.com/

[2] Arlene Gee

[3] Cities for People, Jan Gehl, 2010

[4] Toronto’s Ontario College of Art and Design, Will Alsop Architect

[5] Roland castro rendering. From Vivre le Fleuve, Atelier Castro Denissof Casi / Nexity, Dec 2010, Paris

Traffic to Downtown

April 11, 2011

Following the last week forum, I will blog on the Georgia and Dunsmuir viaduct, to eventually provide a “dissident” voice to the opinion expressed here or there, but as a preliminary, I have gathered the data below I will eventually rely on to support my opinion

Following the bridge traffic data gathering for metro Vancouver, below is a map overlaid with the traffic volume on the main accesses to Vancouver Down Town peninsula.

Traffic on main access arteries to Vancouver Downtown Peninsula (click on the map for more detail)

Some comments on it:
Traffic

  • Traffic volume distribution is hourly, and based on the latest numbers provided by City of Vancouver [1]
  • While most of the traffic Data provided by the city date of 2006, the actual capacity is considered. i.e. 2 lines West on Dunsmuir and 2 line South on Burrard
  • For reference, the skytrain inbound traffic is also provided (numbers from [3]). notice that skytrain trips are not up to scale with vehicle trips

A Note on the road Capacity.

While, at the counting location, Pender street is 4 lanes... Further East, the road capacity is severely constrained by different lane allocation choice and street artefact, we have not accounted for. credit (4)

Very certainly numerous factor like traffic light, left turn, other road artefacts… affect the road capacity which are probably more complex to compute in urban environment than in rural one. We are not a professional in that field, and want to have to rely on ball-pack numbers. the suggested road access capacity are arbitrary, and given to provide a rought idea of probable congestion level which is also probably subject of different perception according to whether we come from Toronto or Prince Rupert.

  • Red line indicate the capacity of the access, assuming a 1400 vehicle/hr capacity per lane. To allow comparison with previous study
  • The orange line assumes a may be more realistic capacity of 1000 vehicle/hr per lane in some urban context
  • Number of lanes per road assumes the lanes also used for off peak parking, this at he counting location
  • For the skytrain, the dash line provides the actual capacity of it, while the red provides the “ultimate” one [3]

Mismatch with Traffic data provided at the April 7th Viaduct forum.

At this forum, Dave Turner of Halcrow had presented some traffic data as reported by Stephen Rees. While the number presented for Dunsmuir and Georgia viaducts are in line with the one provided here. Unless things have dramatically changed since 2006, All other numbers seems incorrect. Probably Dave Turner, was wanting to speak of number of trip and not number of person, so basically all numbers need to be divided per 2:

  • Unless you include the Canada line, there is ~120,000 skytrain trip to/from Down Town [3], that is 60,000 people and not ~110,000 as reported at the forum.
  • We assume that a similar confusion has been done for the number of incoming bus riders, it is probably not 34,000 but more realistically twice less (Someone could have noticed whether Hasting buses were as busy as Broadway ones)
  • And from data traffic we present here, we can probably say the same for it

Regarding the level of congestion- Dave Turner was reporting road like Pender close to capacity- It is not what says our map: We can’t argue on it and the reader will report to the previous section for why.


[1] City of Vancouver OpenData catalogue, When several series exist for a counting station, he most recent available on April 8th, 20111 is used…. That is usually 2006

[2] Traffic capacity of Urban roads, Design manual for roads and bridges, Feb 1999.

[3] TransLink’s Rapid Transit Model, PTV America Inc Report to Translink, Feb 2007

[4] Picture from City of Vancouver

Viaduct des arts, Paris

Viaduct des arts, Paris

Rail viaducts have being a fixture in numerous cities since the introduction of the railway. They can be considered as an urban blight and objectively often disrupt the urban fabric, but here we present some examples showing that it can be different. Surprisingly enough, it seems that it is a reconsideration of the purpose of disused viaduct in the city [2] which has lead to rethink of its urban integration. Typically this consist to bring, under the viaduct, urban activities contributing to the street life: That means not considering the Viaduct as part of the street itself, but as a building lining up the public space.

Vienna, Austria
Viaduct in “median”


A viaduct in Vienna, once a barrier in the middle of an artery, now is a building lining streets on its both sides. Note how the shops lining the street capitalize on the once a median separation (credit photo: Architekten Tillner)

Buenos Aires, Argentina
A Viaduct lining up a park

In Buenos Aires, the viaduct function, is enhanced by street life contributing activities. Again here the barrier nature of the viaduct is fully assumed, separating a park of its urban environment, and eventually reinforced, with this viaduct arch reconsidered as a “passage”, clearly indicating the “human scale” nature of the expected traffic and enforcing the “oasis” feeling of the park (credit photo Polycentric Linear City)

London, UK

Wotton Street, The structure on the right is a viaduct!


Only around 50% of the londonian Tube is underground. this and the numerous railway network left the British capitale heavily sliced by Viaduct “cut”. Lately tremendous effort has been taken to address the issue, as witnessed by the project “Light at the End of the Tunnel” in the context of the “crossriver partner ship program”

Paris, France
Beside the much acclaimed viaduct des arts (a former railway viaduct), Paris is also well furnished in metro viaduct. They offer to us an opportunities to showcase some idea eventually not working that “well” when you treat the space under viaduct as public space.

The Viaduct of Bercy in Paris, while offering an appealing look doesn’t work that well as a bike path host: the cyclist has basically no visibility, and the “enclosed” nature of the viaduct prevent natural washing of the pavement (credit photo: zagreus)


The space below Paris viaduct is rarely appropriated by the public, one reason could be due to the fact that the steel girder structure is pretty noisy on train passage. The fact that the space is in the median line of boulevard is not helping to draw public naturally. bike path could make a better use, but viaduct piles are as many hazard limiting the visibility of the cyclist (one will note that the Richmond viaduct turn out to be more appropriate to such an use) (credit photo, Duncjam and moonmeister)

One will find some other example on the web [3], but the one exhibited here tend to demonstrate that the integration of a viaduct in the urban fabric is something perfectly doable, backing the effort done on the Richmond viaduct.


[1] Light at the end of the tunnel: Transforming railway viaducts in central London

[2] from the viaduct des arts in Paris to the HighLine in New York, there are numerous of disused viaduct going thru a renaissance life, with usually the patform being transformed in a green public space ( a list of some projects)

[3] Noticeabily The reader will find other similar example for Berlin at the HumanTransit blog, and more generally could like to take a look at a dedicated thread on skyscrapercity forum