Fendon Road roadworks - effect on journey times

Fendon Road roadworks - effect on journey times  

  By: jw35 on Sept. 12, 2019, 1:49 p.m.

Earlier this week work started to rebuild the roundabout at the junction of Fendon Road, Mowbrary Road and Queen Edith's Way near Addenbrokes. This is a busy junction and the work involves road closures and temporary traffic lights. You'd expect it would cause traffic disruption, but how much?

SmartCambridge creates and stores journey time measurements based on bus movements for almost 100 road segments ('zones') in the Cambridge region. A number of these surround to road works. By graphing these we can get an idea about what delays are happening where. Here's an example, showing journey times on the cherry_hinton_road_outer_in zone (from Cherry Hinton High Street to Mowbray Road/Pern Road) in the morning peak (07:00-09:00):

cherry<em>hinton</em>road<em>outer</em>in morning journey times

Each blue dot represents a bus journey, grouped by day. The short black lines represent the average (median) of the journey times on that day. The graphs omit Saturdays and Sundays which just add noise.

Interpreting this graph is complicated by other events, such as the reopening of Mill Road Bridge and the start of school term which as shown, but it certainly looks as if this particular journey has become much slower this week.

There are however limits to this technique. Here's a graph for the babraham_road_in zone (roughly the Park&Ride junction to Wort's Causeway) in the morning peak.

babraham<em>road</em>in morning journey times

You might expect this to show significant delay this week, but instead it shows almost no journeys. Further investigation shows that the buses on this route (13, 13A and the Park&Ride) started to divert via Wort's Causeway during the morning peak last week - here's the track of yesterday's 08:22 13A service from Haverhill:

13A 08:22 departure from Haverhill

There's a complete set of graphs at https://www.cl.cam.ac.uk/~jw35/acp/forum-resources/journey_time_fendon_road_area_BUS.pdf. The graphs are arranged in three sections: one showing the morning peak (07:00-09:00), one showing the evening peak (16:00-18:00), and a final one showing hourly mean journey time during the day. We'll do our best to update them from time to time while the road works continue.

There are a couple of places where the road works seem to have clearly increased journey times, but in many cases any increase looks as if it has more to do with the start of school term that with the road works. Why hills_road_outer_out (Hills Road Bridge to Long road) is being quite so affected in the evening peak is something of a mystery.

Jon.

--
Jon Warbrick
Adaptive Cities Programme, University of Cambridge


 Last edited by: jw35 on Sept. 13, 2019, 9:24 a.m., edited 2 times in total.

Re: Fendon Road roadworks - effect on journey times  

  By: jw35 on Sept. 16, 2019, 11:50 a.m.

I've tweaked the graphs slightly to split the 'hourly mean journey time' set into two - one before and one after the start of the Fendon Road works. There are clear differences, but remember that this is close to before and after the start of school term as well so it's difficult to be sure what caused what.

I've also eliminated some spurious data that was causing some implausible average journey times to be reported.

Jon.

--
Jon Warbrick
Adaptive Cities Programme, University of Cambridge