Update, Autumn 2024:
We have now published an interactive dashboard which is designed to provide typical average daily flows by month or by site for the purposes of long-term trend monitoring. This approach to data provision will enable users to access data in a more timely fashion, as the dashboard refreshes on a daily basis.
The data in this dashboard has also been cleaned to remove 'non-neutral' and erroneous days of data from average flow calculations. Please examine the front page of the dashboard for clarity on what this means.
This dashboard is available at the following link:
Cambridgeshire & Peterborough Insight – Roads, Transport and Active Travel – Traffic Flows – Traffic Flows Dashboard (cambridgeshireinsight.org.uk)
The background:
In spring and summer 2019, a series of smart traffic sensors were installed in Cambridge to monitor the impact of the Mill Road bridge closure. These sensors were installed for approximately 18 months in order to gather data before the closure, during the time when there was no vehicle traffic coming over Mill Road Bridge and then after the bridge re-opened.
Due to the success of the sensors and the level of insight it is possible to gain, additional sensors have since been installed in more locations across the county. A traffic count sites map showing the locations of the permanent and annually monitored sites across the county, including the Vivacity sensor locations, is available on Cambridgeshire Insight.
The data
Data from the longer-term Vivacity sensors from 2019-2022 is available to download from the bottom of this page. The Vivacity sensor network grew considerably during 2022 and as a result, manual uploading of the data is no longer feasible. Consideration is currently being given to methods to streamline and/or automate Vivacity data sharing.
The data below provides traffic counts at one-hour intervals, broken down into 8 vehicle categories. Data is provided (with caveats – see bottom of page) from the installation of the sensor up to 31/12/2022.
The 8 vehicle categories are: 'Car', 'Pedestrian', 'Cyclist', 'Motorbike', 'Bus', 'OGV1', 'OGV2' and 'LGV'.
The counts are broken down into inbound (In) and outbound (Out) journeys. Please see the 'Location List' below to establish which compass directions the 'In' and 'Out' are referring to for each sensor, as it differs by location.
Some sensors record counts across multiple 'count-lines' which enables the sensor to provide more accurate counts at different points across the road, for example footways, cycle ways and the road. This is particularly useful for picking up pedestrians. Sensors with multiple count lines often present data for the road, the left-hand side footway (LHS) and the right-hand side footway (RHS) respectively. To determine the total flow, simply aggregate the centre, LHS and RHS count-lines. Please note that new countlines have been introduced over time for some sensors so care should be taken to make sure all necessary countlines are included when calculating a total flow.
In some locations sensor hardware has been replaced and the sensor number has therefore changed (e.g. the Perne Road sensor was originaly named "16" but was subsequently replaced and renamed "44"). Please refer to the 'Location List' file which details the current and previous sensor numbers at each location.
Caveats:
1. Data quality:
A Vivacity sensor performance monitoring exercise was undertaken in 2022 to determine the level of accuracy of the Vivacity sensors. The findings of this exercise are documented in a technical note. The note helps to highlight data limitations and provides guidance on how best to work with the Vivacity data. A key finding within the note is that the v1 hardware Vivacity sensors (a small group of older hardware sensors) have been found to struggle to accurately count pedestrians and cyclists. As of December 2022, the only sensors that continue to use v1 hardware are on Milton Road (s13), Coleridge Road (s3), Vinery Road (s4), Coldham's Lane (s7), Devonshire Road cycle bridge (s12) and Hills Road (s14). Full details are provided within the tehcnical note. The note also helps to highlight data limitations and provides guidance on how best to work with the Vivacity data.
2. Data gaps:
The sensors are designed to capture data 24 hours per day, 7 days per week however there are occasions when sensors go down and are not able to capture data or only capture partial data that is therefore not representative.
The Research Group make every effort to remove data believed to be misleading but this cannot be guaranteed and the user is responsible for sense checking the data and excluding anything considered erroneous prior to use. The Research Group exclude days where very low or zero flows have been recorded for the day. Within the spreadsheets, these rows will simply appear blank when downloaded – indicating that the sensor is live and active during this time, but the output is not deemed reliable enough for publication.
3. British summer time / clocks changing:
The data is provided in hourly intervals in the local time zone. When the clocks go forward at the end of March and the clocks go backwards at the end of October there are therefore missing / duplicate hours included within the data.
On 27 October 2019, 25 October 2020, and 31 October 2021, all countlines will show two separate values for 1am. This is due to clocks going back at 1am in the morning on these dates. As these days were all 25-hours long we have kept both instances in the data for full transparency.
Similarly, all countlines on 29 March 2020, 28 March 2021, and 27 March 2022 will show no values at all for 1-2am. This is due to the clocks going forward by one hour on these dates meaning they were 23-hour days.