Road bridge numbers and maintenance: EIR release

Information requested

I am asking, under the Freedom of Information Act, the following set of questions:

Defining a “road bridge” as a structure with a span of 1.5m or more providing public highway passage for motor vehicles over an obstacle such as a watercourse, railway, road or valley, please provide the following information for all road bridges for which you own as highway authority, including those which are jointly owned with another authority, but for which you are the lead authority:

1. How many road bridges are you responsible for maintaining?  

2. For the last financial year (2018/19) how many Principal Inspections have taken place

3. For the last financial year (2018/19) how many General Inspections have taken place?

4. For the last financial year (2018/19) how many Structural reviews and/or BD21 assessments have been conducted?

5. How many sub-standard (in terms of capacity) and/or weight restricted bridges do you have?

6. Of these, how many do you intend to return to full load carrying capacity in the next 5 years?

7. How many bridges would you return to full load carrying capacity if you had no resource restrictions?

8. (i) How many of your bridges require post tensioned special inspections (PSTIs)?

(ii) How many of those have had PSTIs within the last 18 years?

(iii) Of those that have not had a PTSI, how many require/are due one?

(iv) How much funding would you anticipate is required to remove the backlog of PTSIs for those bridges identified in Q8(iii)?

9. In monetary terms, what is the current Depreciation (i.e. difference between your GRC and DRC as declared for your WGA return for 2018/19)? 

10. Have you calculated your back log (or workbank) for bridges? What is the calculated value of your backlog of road bridges, or your best estimate if a calculated value is not available?

11. (i) What is the annual revenue works budget for maintaining your bridge stock?

(ii) What is the annual capital works budget for maintaining your bridge stock?

(iii) What total budget would you estimate is required to maintain the bridge stock at its current level (standstill budget)?

12. (i) How many BD97 Stage 1 Scour Assessments did you undertake in 2018/19?

(ii) How many BD97 Stage 2 Scour Assessments did you undertake in 2018/19?

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.

There is information already in the public domain on the Transport Scotland website at https://www.transport.gov.scot/transport-network/roads/bridges-and-structures/#. This section of our website answers some of your questions. However, please find the following information in response to the questions you have posed.

1. For the requested definition, we are responsible for maintaining 2,589 ‘road bridges’.This definition encompasses some culverts with span greater than or equal to 5m as well as bridges which we define as having a span greater than or equal to 2.0m.

2. For the last financial year (2018/19) the following number of Principal Inspections have been undertaken: 287.

3. For the last financial year (2018/19) the following number of General Inspections have been undertaken: 976.

4. For the last financial year (2017/18) we have undertaken 5 Structural Reviews to BD101 and 8 assessments to BD21.

5. There are 29 sub-standard ‘road bridges’ assessed as having a structural element with a load carrying capacity less than 40/44 tonnes, current national weight limit.  There are no signed weight restrictions or traffic restrictions applied to any sub-standard Scottish trunk road structures.  These are operated and managed without restrictions and have bespoke monitoring regimes that are reviewed annually to take account of any deterioration or change.  Traffic volumes and mix are monitored to ensure loadings set down in the assessment codes are not exceeded.  None of the trunk road sub-standard bridges exhibit any distress or have any deterioration or load patterns that require restrictions to be applied.  Whilst it is safe to do so they will be operated normally.  However, this is subject to ongoing and annual review and could change.

6. 14 ‘road bridges’ are programmed to have sub-standard elements upgraded. However, programme and progress depends on budget allocation and competing priorities.

7. In our view, with no resource restrictions we would aim to return all bridges with sub-standard elements to full capacity, as budget allocation and competing priorities permit. Those with weak verges will continue to be monitored and vehicular access to the verges permanently restricted where required.

8. (i) 17 bridges require post tensioned special inspections (PTSIs).

(ii) A full programme of PTSI was undertaken in the 1990’s at 85 bridges. 13 bridges have had PTSI’s undertake since 1998. Reviews are undertaken, in line with BD54/15, during Principal Inspections at least every 6 years or sooner where required.

(iii) 17 structures are programmed to have PTSIs.

(iv) Approx. £341,000 is required to carry out our programme of PTSIs.

9. The cumulative bridges depreciation, as reported in our annual accounts at 31 March 2019 was £2,220,996,573.  As previously noted, Transport Scotland uses the Road Authorities Asset Valuation System (RAAVS) model for recording all structures, the same model as used across the rest of the UK by Highways England, the Welsh Government and the Department for Infrastructure in Northern Ireland.

10. The adjusted value of the Scottish Trunk Road Structures Workbank is £1.07Bn at 2018/19 prices.  This figure includes all prioritised essential works including; planned maintenance, strengthening, improvement and replacement to all structure types.

11. (i) The annual revenue works budget for maintaining our bridge stock was £1.63m. 

(ii) The annual capital works budget for maintaining our bridge stock was £66.8m.

(iii) The total budget required to maintain our bridge stock at its current level is approximately £80m (2018/19 including lump sums).

12. (i) 688 BD97 Stage 1 Scour Assessments were undertaken in 2018/19.

(ii) 104 BD97 Stage 2 Scour Assessments were undertaken in 2018/19.

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