Thursday 6 June 2013

Bristol doesn't have a congestion problem -it has a firstbus problem

In April Tom-tom published a report saying Bristol had the worst congestion in the UK mainland.

As Bristol's premiere traffic data collection and analysis organisation, we disagree.

It's bad data
Tomtom are using data from their customers who have their tomtom dashboard GPS units, their premium "linked with tomtom" service, and have them turned on.

Who still has one of those? We've moved on from dashboard GPS units unless you are minicab drivers trying to get to random destinations in a 10 year old nissan.

Modern cars have them built in -so all the premium vehicles in the city aren't providing data to tomtom. Everyone else: smartphones, giving us maps, the traffic while letting us complain about it on facebook (tip: don't do it on twitter as it's then public).

If you do have a tomtom unit, do you really turn it on in the morning? Where the jams are will be predictable: M4, M5, M32, A4 portway, A4 brislington, A370, A36, A38. See that? Roads beginning with an M or an A. There are some B-roads which are relevant too, Whiteladies road, for example.

Conclusion: only a subset of drivers provide data to tomtom -and because it is not a randomly sampled subset, can't be expanded to everyone else.

Locals know the rat-runs.

Again, we in the know use the rat-runs. A4 portway to clifton? Nope: Roman Way and up to the downs, then Pembroke Road as a 35 mph alternative to Whiteladies. M32 to cabot circus? Off at St Pauls and then -well, that's a secret, isn't it?.

We know the routes, we don't need any GPS units. Indeed, we turn them off precisely because we don't want Tomtom to sell the data on our driving speeds to the police.

This means that the people who get across the city fast aren't producing data.

It's giving rush hour numbers

London doesn't have a rush hour. It has "weekdays", where the jams begin everywhere within the M25 ring, and often on the approach. When we take the Range Rover to London, we always speed over Wiltshire, in the expectation that from Reading it will crawl. This is also why Reading residents take the Bristol trains to and from London, even standing near our seats in First Class.

In Bristol, the rush hour starts at about 08:15, and peters off by 9am, with the exception of those people on the M32 who don't know the alternatives.

This is why Tomtom complain that at peak hours journey times go up "by 31%". What they really mean is "journey times go down by 25% outside the rush hour". Which is something to be proud of.

It's missing the point that Bristol is a compact city.

It doesn't matter that the journey times -from their inadequate sample set, on the main roads only, at peak hours only, shows that the mph of cars is about 14 mph.

Yet Bristol is a fraction of the size of the city. 14 mph gets you from filton A38 to the city centre in half an hour. In comparison, 14 mph in London would get you from slough to somewhere between the A312 and Kew junctions of the M4, three roundabouts on the A312, or, if you are on the M25, nowhere at all.

Summary: it's quoting rush hour numbers collected from a bad sample-set of drivers, then exaggerating the problems by failing to take city size into account.

It's also not looking at why the big discrepancy between rush hour and rest-of-day times exists. It is due to people commuting in to the city from outside.

Why do they do that?

  • They've chosen to live a mock-rural-life in Somerset or South Gloucs, in the dorm towns of Portishead, Clevedon, Weston-s-m, Yate, Thornbury etc, and still want to get to work in the city. It was a bad decision, and if they are stuck in traffic every day, they should recognise that is the price they have to pay for moving out of the city. Rather than whine: shut up and move back.
  • There is no alternative. Portishead really needs the railway back -it would be profound, but for everyone else, especially those in Bristol and S Gloucs, the alternatives to driving are cycling and public transport. Anyone who has used FirstBus will realise that sitting in a traffic jam on the M32 can be a better alternative. The journey time is the same, the cost is less, especially if there is more than one of you in the car.
The cost of FirstBus is clear if you ever use the Severn Beach railway line. Not only is it always on time, it is fast across the city -and a fraction of the price. 

If we have a problem, then, it is the lack of a decent public transport infrastructure pushes people into driving, creating the congestion problems at peak hours -and parking problems all day long.

This is why Bristol Traffic supports the Resident Parking Zone proposals

More to follow


Rick said...

Whiteladies Road is the A4018

Matt Man said...

20mph speed limit in all of Bristol City borough near enough, so 14mph average just accounts for traffic lights.

I have lived here 6 weeks and astonished by how well traffic flows once you understand the road system.

Not sure at the M32 dig, even with road works its been flying fine at 40-50mph out of rush hour, and similar in rush hour. Which is its limit being inner city. Much faster then 20-30mph parrelel roads like gloucester or filton which which have many poorly parked cars.

Biggest congestion problem is illegally parked cars, usually taxis, blocking traffic and cycle lanes, a pain and dangerous for cyclists.

FirstBus monthly or annual tickets, especially for young people (30% disccount) is still reasonable, 3 or 4 taxi rides would cost a months bus pass.