Increasing urban permeability brings great benefits to the town or city.  Yet I wonder too if some places don’t owe their own special character to the very fact that they are not highly permeated – places where a sense of enclosure is the very essence of the place? Would monastery cloisters, for example, which exist as refuges from the hubbub of urban life, have any meaning if they were mere incidents on the route to somewhere else.

Some great new walkable link routes have been created in Dublin and Dun Laoghaire and have greatly increased the permeability of their urban blocks for pedestrians – Blooms Lane, the Millennium Bridge, Haigh Terrace, Cows Lane… But is more permeability always appropriate?

Generally, we’d deploy an arsenal of persuasive reasons to convince stakeholders as to why it’s the right approach:

– An increased choice of routes is made available to pedestrians
– Better, more pleasant routes are made available to pedestrians if the routes are well designed
– Shorter routes are made available and so more convenient walks are offered to users
– Inaccessible backlands or brownfield sites become available for development
– Under-appreciated squares or streets can be revealed to pedestrians
– New vistas can be opened up by the careful alignment of new walkable links
– Linkage can be strengthened or indeed created between isolated areas, thereby increasing overall activity in both areas
– Walking is encouraged over driving as more places are accessible on foot
– Pedestrian consumers can be channelled into a retail or cultural zone they might have otherwise avoided

But is permeability the right response everywhere?  Here are a couple of illustrations – one extreme, one benign – where it could plausibly be argued that maybe more would be lost than gained by increasing the permeability of certain large urban blocks.

At one extreme is the suggestion (very tentative, perhaps facetious) published in the Irish Times in 2004 to run the LUAS light rail through, rather than around, Trinity College.  This proposal would have opened up a north-south route through the college, a route not easily negotiated at present outside of rush hours.  “It would be cheap and would open up the vista and atmosphere of Trinity College to the ordinary people of Dublin”.  And yes, of course all the positive results of permeability listed above could be said to apply, especially the advantages to pedestrians in a hurry to get across the city to somewhere other than the college. But the loss of the college precinct as a place of quiet in the heart of the noisy city, as a special refuge of tranquillity within its walls would be a tragedy for Dublin citizens.  Not all dead ends are lifeless.

More benignly, a case could have been made for the Iveagh Gardens, where the western and southern entrances are relatively easily encountered, but the eastern one is at present quite hidden, behind the site of the proposed National Children’s Science Centre.  Although when first laid out they were fully open to what is now the National Concert Hall (and will be again with the NCSC), the gardens have meantime become an almost secret place, often now described as an oasis of tranquillity when compared to the bustle of adjacent St Stephen’s Green, which is highly permeable. The two adjacent parks have thus become complimentary, offering contrasting experiences. The attraction of the Iveagh Gardens at present is precisely because of its perceived lack of permeability. The loss of this sense of enclosure in the gardens could be considered the opportunity cost of the gain to the city of the new Science Centre.

This is not to argue for concealing amenities from the general public, just an argument for not always flaunting these spaces to passers-by. A great urban environment will embrace all points on a spectrum of great spaces, from popular vibrant busy ones to quiet ones which of their nature are not so obvious and therefore not so busy.  So perhaps it is worth bearing in mind when mooting an increase in permeability in a city or town that, sometimes, in some places, a little less permeability can also be a good thing.

Gerard Bourke
Senior Architect
Dun Laoghaire Rathdown County Council