Tuesday 23 September 2014

Unintentional Experiments

Sorry. It's been a while, but we've all been a little busy up here in Scotlandshire recently. Normal service resuming.....

Glasgow city council has been running an experiment, an experiment in traffic flow. Interestingly, I don't think Glasgow has even realised that it has been running it. In fact, it's not actually called an experiment, it's called:

Bridge Work Repairs.

Yes, there are bridge repairs ongoing on my commute to work which have resulted in a section of road where 4 lanes have been reduced to two. The roadworks are here

You can see that there are two railway bridges and it just so happens that a decision was made to repair them both at the same time, which is an unusually good idea. What didn't seem like such a good idea was that the work was to begin just after the Commonwealth Games and just as the schools were returning. Oh dear.

Anyone who recognises this road from my videos will know that it is very often choca-block with cars.

At rush hour it is not unusual to see a mile of tailback traffic leading up to this area which can when things are particularly bad (often for no obvious reason) tailback about 3 miles. So when I learned that this work was starting, and when I learned that the work would be carried out over 18 weeks, one thought came to mind.....


I predicted that I would be filtering through 3 or possibly 4 miles of traffic for 18 weeks. Joy.

After the first day of the road works when the traffic was indeed heavy I posted the following tweet:

In fact, another local Tweeter replied agreeing with me:
We were both completely wrong. We couldn't have been more wrong.

Yes, on that first day traffic was heavy. Not exceptionally heavy, but that wasn't surprising as the schools weren't back yet. However, after that, and it is still the case with the roadworks ongoing, I had never seen the traffic flow more freely. Not only did 'Carmageddon' not come to pass, but the standard tailbacks disappeared. At worst the traffic has only tailed back as far as Anniesland Cross, and even there it flows.


It's true, and I'm not the only one to notice it. My wife who regularly drives down that road (a little earlier than I cycle it) says she has never seen the traffic flow so freely. Others that I know who travel down this road say exactly the same.

So what is going on?!

How can a road lose two lanes and flow more freely?

Now I'm no traffic engineer or urban planner, but I've been making  a few observations and this is what I've noticed.

The works haven't just closed off two lanes on Crow Road, they have also closed the junction at traffic light controlled junction at Southbrae Drive (you can see it in the map above just north of the two railway bridges. There has also been a slight change in the light phases at the junction Abbey Drive/Crow Road (to the south).

The junction closure and the phase changes have effectively allowed traffic to pass through an area that usually acts as a bottleneck. Traffic rather than being stopped every so often, flowing through without serious interruption. Yes, there is an overall reduction in flow rate, when the traffic is flowing, but it is following at the slower rate for longer.

Of course, there are possibly other factors affecting the volume of traffic. It is entirely possible that drivers know the roadworks are there and are taking alternative routes, although I've not noticed or heard of any knock on congestion (even where the junction closure has forced alternate routes). It is also possible that some drivers are taking alternative forms of transport.....God forbid...perhaps even cycling! Of course if they are, then this is a benefit.

Perhaps traffic is generally quieter due to other factors. The weather perhaps (it's been quiet on very wet days as well). Maybe lots of people have moved out of the area at once, though I suspect this is a tad unlikely!

Perhaps though, and surprisingly I think this is the most likely, the closed junction and the changed traffic lights priorities demonstrate that this road could be re-engineered to reduce the number of car lanes without having devastating effects on travel times.

OK! I'll admit this is a simplistic analysis. It's a bit different converting 3 miles of dual carriageway to single carriageway, compared to just reducing a small section to single carriageway. There would be other knock on effects. What this experiment does demonstrate though is that with a bit of thought, a bit of planning and a bit of give and take, more space can be found even on the busiest of roads for.........yes you've guessed it...... cycling.


Imagine just taking one lane away from the four on this road. Imaging putting in a segregated route all the way along this route. Imagine if the traffic was managed in such a way to keep it flowing. Imagine the amount of people on this route that, seeing a safe and easy to use cycle lane, might actually decide.....hmm.....  I might just take the bike today.

On this occasion, the road closures were forced upon us. Yet, the predicted chaos never materialised. Imagine if the politicians had the vision to try it for real and to make the roads safer for alternative forms of transport at the same time. Perhaps it would start a revolution.....


  1. Yes to this. THIS is precisely where OpenGlasgow should be putting their money - they should be studying before/after traffic rates. You're a scientist :-) you understand that an experiment is useless if you don't actually do any measuring!

    I've made a similar point about the Fastlink segregated path on Broomielaw - in the absence of the buses, this has become a de facto cycle path, and yet I'm not aware of anyone actually measuring whether or not cycle traffic has increased here.

  2. Dead right Dave, traffic flow and my commute have improved tremendously since this lane closure. Who's listening though? When will a motoring organisation appear on the radio asking for a lane closure to be made permanent?

  3. Devil's advocate here. If the phasing of the lights at the junction you describe has changed in favour of drivers going north-south (or vice-versa) then surely drivers (and cyclists) exiting Abbey Drive now have a shorter phase and have to wait longer on average? And what about people who used to come out of Southbrae Drive? Are some people diverting up to Woodend Drive - rat-running?

    Certainly I would expect to see some benefit based on induced demand but I'd be surprised if that made the road noticeably quieter on its own.

    I'm not saying that the phasing change is a bad thing* but it might not be fair to present this as a situation where everybody wins? Is this just a case of "I'm all right jack"? Because unless the intervention has changed modal share - unlikely given the time-scale - all that traffic is going somewhere and quite possibly pissing somebody else off.

    *The lights on the crossroad at the end of my road make me wait for ages when turning out, but that makes my road less appealing as a rat-run, so I'm all in favour of it.

  4. just off the cuff here!
    im a cyclist and a van driver btw
    a no right turn at this junction would keep things moving southbound and cars would need to take alternative route to get to this road from Anniesland cross area past the driver test area etc or via Lincoln avenue
    but no right turns northbound at the railway staton and the lights would have cars having to come from Anniesland cross to enter them .i think?
    this leaves all left hooks waiting to happen if cycle lanes were to be added as well

    I could see a busier Anniesland cross junction at peak times

    maybey im wrong and need to check out the roads here again.