Roads simply can't cope with volume of traffic
Gridlock. That is what greeted Belfast motorists yesterday in one of the most snarled-up mornings in many months. What caused the mayhem?
Undoubtedly, the root cause was a crash on the Westlink that occurred at 4am, causing the road to be closed completely from York Street to Divis Street.
It took until 8.30am - the height of the rush hour - to remove the vehicles from the road. In the meantime the city had awoken.
York Street is the hub of Northern Ireland's road network, where our three busiest roads meet. The M2 carries almost 100,000 vehicles per day, the M3 around 90,000 and the Westlink about 80,000.
Yesterday thousands of vehicles approaching York Street from the M2 and M3 found their way blocked and were forced onto city centre streets which have nowhere near the capacity to absorb them. Result: gridlock.
Yet cars kept joining the back of the queue, which meant that traffic soon tailed back as far as Templepatrick and along the A2 towards Bangor.
Vehicles trying to reach the M3 from north and east Belfast found their way blocked, so soon the jams spread out along the arterial routes - Antrim Road, Newtownards Road and Castlereagh Road. People then, understandably, tried alternative routes and these, too, were soon snarled up.
By the time the Westlink reopened at 8.30am it was too late and large parts of the city were at a standstill.
Immensely frustrating, but what is the wider cause? Fundamentally, the problem is that in the rush hour the city's road network is running well over capacity.
TransportNI has a sophisticated traffic light control system that constantly tweaks the signals, and that improves the situation to a surprising degree. But it doesn't solve the underlying capacity problem.
One solution would be to build more roads. This was the approach that the authorities followed from the 1950s until the early 1990s.
As time wore on it became obvious that this could not be sustained without building roads so wide that it would involve demolishing large parts of the city they were meant to serve. For traffic to flow freely on the Westlink in the rush hour today would require it to be 10 lanes across.
In 1995 the Government formally abandoned this policy, and since then has focused on the more modest goals of removing key bottlenecks.
Cars are a very inefficient use of road space, so there have been increasing efforts to try to get people to switch to the train, the bus, the bicycle, or foot.
This is the aim of Belfast's derided bus lanes, to get more people into the same road space.
There is still much to be done, and not everything has been a success, but there are few alternatives.
- Wesley Johnston is author of The Belfast Urban Motorway (2014) and runs the Northern Ireland Roads website, www.wesleyjohnston.com/roads