Activation of ice warning sensors Queensferry Crossing: EIR release

Information requested

Between  the 25th of December and 2020 and the 25th of January 2021 how many a) times and b) on what dates have the ice warning sensors been activated across the Queensferry Crossing?

Response

As the information you have requested is 'environmental information' for the purposes of the Environmental Information (Scotland) Regulations 2004 (EIRs), we are required to deal with your request under those Regulations. We are applying the exemption at section 39(2) of the Freedom of Information (Scotland) Act 2002 (FOISA), so that we do not also have to deal with your request under FOISA.

This exemption is subject to the 'public interest test'. Therefore, taking account of all the circumstances of this case, we have considered if the public interest in disclosing the information outweighs the public interest in applying the exemption. We have found that, on balance, the public interest lies in favour of upholding the exemption, because there is no public interest in dealing with the same request under two different regimes. This is essentially a technical point and has no material effect on the outcome of your request.

Under the terms of the exception at regulation 10(4)(a) of the EIRs (information not held), Transport Scotland is not required to provide information which it does not have. We do not have the information you have requested because alerts come from the weather forecasts (low, medium, high and severe) not the ice and climate sensors. These sensors provide live data which can then be compared with the forecast.

This exception is subject to the 'public interest test'. Therefore, taking account of all the circumstances of this case, we have considered if the public interest in disclosing the information outweighs the public interest in applying the exception. We have found that, on balance, the public interest lies in favour of upholding the exception. While we recognise that there may be some public interest in information about ice sensors, clearly we cannot provide information which we do not hold, however the following information may be of help.

To manage the risk of ice accretion on the Queensferry Crossing our Operating Company receives forecasts of the climate parameters conducive to ice accretion, which are updated at multiple times throughout the day. The forecast parameters are monitored, and a risk of ice accretion level is calculated. The system informs the Operating Company of periods of elevated risk and patrols are scheduled during these times. Patrols of the bridge and additional monitoring are undertaken during forecast severe and high risk periods.

The patrols monitor the bridge during this time and if ice is observed accreting on the bridge the bridge is closed.

The array of sensors on the bridge record the climate parameters conducive to ice accretion. This includes present weather, precipitation levels, temperature, humidity, dew point temperature, and wind information. This information provides a real time update of the observed risk level and records a detailed account of the parameters during an event.

During the period in question, the 25 December 2020 to the 25 January 2021 inclusive, the highest risk level (severe) based on the forecast was triggered on 7 separate days:
28/12/2020
29/12/2020
05/01/2021
07/01/2021
13/01/2021
20/01/2021
21/01/2021

This period was particularly active as there was a significant number of snow and sleet events forecast for the area during this time.

About FOI
The Scottish Government is committed to publishing all information released in response to Freedom of Information requests. View all FOI responses at http://www.gov.scot/foi-responses.