Archive | March, 2014

Rethinking Birmingham’s Dual Carriageways

14 Mar

Around the South and South-west of Birmingham particularly, there are a number of dual carriageways that follow a very similar layout. As I haven’t been out with a tape measure, rough estimates where the best I could manage. But here is a rough guide:

Image

As an urbanist (albeit amateur) this road represents, at a basic level, an inefficient use of space. However there are bigger issues to be found while travelling along these roads. (Dual carriageway section starts at 3:37)

As you can see in the video the left-hand lane is occupied sporadically by parked cars: not enough to close down the lane completely, but enough to make it a real pain to use. Cyclists and drivers moving at 30 mph or less (I also drive along these routes, at the speed limit) will generally find themselves forced into one of 3 options:

  1. Dodge in and out of left lane when gaps in the traffic and parked cars allow, which is both time and energy consuming.
  2. Cycle along the median line, putting up with close passes on your right and the possibility of being doored on your left (cyclists only).
  3. Take the lane and put up with the resulting impatience and aggression from following drivers.

This makes it a pretty much a damned if you do, damned if you don’t issue. Labelling and setting these roads out as dual-carriageways does not in fact provide any benefits. The random nature of the on street parking makes diminishes the predictability of the road and merely creates confusion and conflict. As well as this the dual-carriageway approach does not actually increase traffic flow, as combination of cars acting as pinch points and the eventual downgrading to one lane causes traffic to bunch up at points.

Therefore I two proposals for possible solutions to the space. The first is to narrow the grass verges and left hand lane slightly (converting it to parking bays), while at the same time moving the now dedicated parking lane to the right to make space for a protected bike lane along the inside of the parking bays.

bham-dual-carriageway-remix1

The second is to remove the left lane entirely and replace it with a  protected bike lane, while at the same time allowing parking on the section of the resident’s driveways that is parallel to the grassy verge.

bham-dual-carriageway-remix2

Both designs remove a unused traffic lane, make little or no difference to car parking (note: the majority of houses along these routes also include spacious driveways, provide protected space for vulnerable users, reduce pedestrian crossing distances and increase the traffic flow of the roads. One of the most prominent arguments that council planners have against bicycle infrastructure is the lack of space on the roads, which is quite clearly not an issue in these areas. Designing infrastructure onto roads such as these could be seen as a quick and relatively painless win, in getting decent cycle infrastructure in on the ground.