Finding Lost Space

Williamson Ave dragstrip. Auckland

The “flush median” is a pernicious road design that lingers in many places around Auckland and is still being utilised in many new road designs. I can only guess that its genesis originated in the late 60’s as a way to separate cars from the most severe of collisions, the head-on. It remains today, as that pesky give-way rule did, as a sort of monument to a particular era of traffic planning.

Besides providing a buffer distance between moving vehicles the flush median’s main purpose is to let cars turn left or right whenever they want, as infrequently as it may happen, while not obstructing the almighty flow of traffic. The flush median by design reduces the friction between vehicles moving in opposite directions and raises driving comfort and ultimately speed. Other such safety-minded designs such as the introduction of wide lanes, the removal of hazardous objects (aka trees), and over-scaled intersection geometry all are a form of “passive” design, an effort to physically design safety features into the environment. With the benefit of hindsight we know that this well-intended design philosophy combined with the desire for unimpeded flow often makes streets more unsafe, since it leads to speeding and driver inattention.

The unintended consequences of modern traffic engineering has now been widely documented on blogs like Strongtowns, and general audience books like Walkable City and Traffic, where Tom Vanderbilt sums up the situation nicely:

The pursuit of a kind of absolute safety, above all other considerations of what makes places good envrionments, has not only made those streets and cities less attractive, it has, in mnay cases, made them less safe.

So back to the flush median. There are opportunities in Auckland to recapture this space for better uses that in coordination with more progressive street designs will serve a wider range of users, notably people walking and on bikes. I’ve seen example of this wasted space along parks edges, in town centres, and even remnants lingering in the cbd– all places you would never need a turning lane, let alone a street design that encourages speeding.

A little trickier perhaps, but I see a street like Williamson Ave in Grey Lynn as a good candidate for such a rethink. The street is primarily residential in context, though it does serve a  morning peak hour pulse of traffic (including buses) in a sort of “grids gone wild” way.  Does it really need a flush median from end to end? I think it would be better served by a single central stripe with a few devoted (and short) turning pockets at a couple key intersections. This would open up the street to bike facilities which would have a significant network function of bringing people into the city centre.

Looking east along Williamson Ave towards Ponsonby Road, Auckland, 1963. (Sir George Grey Special Collections, Auckland Libraries)

There’s a lot that can be done in a street cross section when you “find” an extra 2.8m.  With changing values,  different economic circumstances, and a better understanding of how cities work, there’s no better time to reconsider the simple allocation of space in our urban environment. To return to a quote used before on this site from Enrique Penalosa:

“Urban transport is a political and not a technical issue. The technical aspects are very simple. The difficult decisions relate to who is going to benefit from the models adopted.” -Enrique Peñalosa

Residential through street, Melbourne. (Google Streetview)