Junctions design and average speed

Bremen is my German study location, and when visiting this quite wonderful city in August last year, I was lucky enough to become part of a technical experiment. Film maker Richard Grassick was eager to trial his new equipment including a gimbal – oh yes. The gimbal was smoothing our ride, which Richard otherwise filmed using a GoPro camera. We were cycling up and down and around the city. On my last day before heading back to Newcastle, I had cycled out to the university campus in the North (I reported on the good and bad), carried on beyond the ring road before looping back southwards. On my return Richard met up with me near the campus and, together, we cycled back to the centre (via Wachmannstraße and Contrescarpe).

The footage currently comes in very handy indeed for my interviews – I have started my pilot studies just this week. For me, the start of the interviews deserved a big fat mark in my diary – a massive milestone has been passed. But the footage also got me thinking about comfort (yes, infrastructure, infrastructure, infrastructure) and convenience (such as time competitiveness with other modes) again. From the footage it was easy to extract waiting times at junctions… so here are some stats valid for this particular trip Richard and I made in August 2015

Distance cycled: 5.01 km

Time cycled: 24 min

Time waited at junctions (speed = 0): 4 mins

From that it can be calculated that

Average journey speed: 12.6 km/h

Average journey speed without waiting (max potential): 15.1 km/h

That would mean that the trip time could be cut by 16% (that’s the percentage that was spent on waiting) which would increase the average speed from 12.6 to 15.1 km/h.

From my observation and watching the footage again, some junctions were better than others: the encountered waiting time was acceptable at some junctions or simply because priority had already been given to the direction we were travelling in. Worth mentioning is one of the biggest and most complex junctions on the stretch (roundabout with a tram ‘hamburger’) called Am Stern (at the star) where the waiting time was negligible (due to no conflict with tram route) – Richard previously filmed the roundabout here if you are into tram hamburgers or simply like to get an impression of the junction design.

As for my general style of cycling? I prefer a relaxed speed, I’d say, continental style. The footage shows that for about 1.5 miles I cycled alongside a woman with a kid in her trailer. We were going at roughly the same speed. I should add, that I would perhaps take regular journeys (commutes…) faster. But after all, on that day in Bremen, I wasn’t on a particular schedule, deadline or ETA. I would maintain however that the road environment and infrastructure greatly determines the cycling style you adopt. I noticed that on links (in between junctions) I cycle much more hurriedly in the UK (no cycle infrastructure to speak of, particularly not along main roads). This is to reduce my differential speed with motor traffic as well as the time spent in motor traffic. (I am not alone in that. Several studies have shown, not surprisingly, that people do not like to mix with motor traffic, and protection and separation on main roads is key to mass cycling.)

If you could start to think about comfort and convenience for cycled journeys we would afford a similar rigour to the one we currently give to driving, through technical practices like ‘smooth flow’ modelling and junction capacity assessments. We would design for optimum speeds and minimum waiting times, reduce number of stops and we would smoothen the speed envelope. Much energy is lost for cyclists on re-starts.

But we aren’t there yet. Not even in Bremen (which is Germany’s city over 500.000 inhabitants with the highest cycle share at 25%). Designing for an overall journey experience by using parameters and data and take a much fuller account of the cycling experience along the route is a long way off still.

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3 thoughts on “Junctions design and average speed

  1. It would be interesting to have a comparison of delay for each of the transport modes along the route, are some given more priority than others? It is common for trams and trains to have highest priority, but beyond that it varies widely around the world.

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  2. On this route only the tram and buses get priority when they approach the roundabout “Stern”. And cyclists have priority over cars at the “Stern” exits. In Germany it is also common that cyclists and pedestrians have green lights with cars of the same direction at junctions with traffic lights, so of course drivers have to stop for cyclists and pedestrians when they turn left or right. (Which legally they should do in The UK as well but simply don’t.)

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  3. Would there be much value in cycle commuters documenting their wait times at junctions for the benefit of road designers?

    There’s a particular two-stage crossing on the CS3 near Westferry that I use twice daily that feels in need of a change in the light sequence. It’s common to wait for 30 seconds at a red light without seeing a single car go past, and then do it again for the second half of the road. It’s rare to wait that long without seeing another cyclist go through the red light.

    I think a tunnel would work well here since the land on the south side is already two metres lower than the north side, but they’re expensive so the CBA would have to be pretty solid to justify it. How much cost do 2,000 cyclists per day waiting an average of 120 seconds (30 seconds at each stage in both morning and evening) account for in a CBA? And does this change if their actual behaviour is to ignore the red light instead of waiting?

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