Risk Based Inspections (Overview)

London Bridges Engineering Group (www.LoBEG.com) has developed a good practice guide for Risk-based Inspection of Highway Structures. BridgeStaion Risk-based inspection (RBI) module implements the recommendations of this Good Practice Guide. This article provides an overview of the RBI GPG and how to use the RBI module on BridgeStation to develop a risk-based inspection programme.

It is highly recommended that the above GPG should be reviewed before using BridgeStation RBI Module. BridgeStation automates all calculations and proposes inspection intervals for PI and GI. So understanding how risk analysis is carried out is important for reviewing BridgeStation outputs and overriding them according to local knowledge, if necessary.

It is highly recommended that this module should be used by a competent structure engineer. 

As explained in the GPG, an overview of the process for determining the risk-based inspection interval and the inspection programme is shown below. Steps 1- 5 are automated on BridgeStation and data required for completing the analysis are highlighted in the Data gap reports.

The BridgeStation data gap report highlights the list of data fields required to complete the analysis. Data gap reports can be accessed via the report menu as shown in the image below. 

The "Basic Data" and the "Risk-based prioritisation" tabs show the list of fields required to complete the risk-based analysis.

The first step for developing a risk-based analysis is to review the risk score and proposed risk-based intervals for each structure. BridgeStation automatically analyses the risk and calculates the "proposed Risk-based Inspection Interval". This analysis can be accessed through the inspection menu item as shown below.

A summary dashboard highlights the stock level analysis. Analysis rates structures risk into five categories (Very Low, Low, Moderate, High and Very High). 

The first chart shows structures that are at very high risk and should be inspected at lower intervals than the time-based regime (ie 6 year PI and 2-year GI). The second chart highlights the structures with low (or very low) risk categories that can be inspected less frequently. The user can click on the "View Details" link below each chart to review the list of structures in the respective category. 

As shown in the above image, click on the "Review Risk Scores and RBI Interval" Button to view analysis for each structure.  A partial view of the analysis grid is shown below. Scroll to the right to review the RBI inspection interval for each structure.

Details of analysis/calculations can be found by clicking on the "details calc" link ("Detail Calc" Column).

To export data on a spreadsheet, click on the "export data" button.

There may be exceptions to this process based on local knowledge or policy adopted by the local council. ie you may want certain structures to be inspected at specific intervals irrespective of the analysis. Or you prefer some structures to be inspected together for operational purposes. 

To add custom/user-defined risk analysis (ie risk interval and rationale), click on the edit button as shown below to specify user-defined inspection intervals for PI and GI. BridgeStation will automatically pick the user-defined interval while developing an inspection programme using the planning tool.

Once intervals are reviewed you can then use the inspection planning tool to develop an inspection programme. Below is a quick overview of the steps involved.

To help users with identifying the best programme, an inspection planning tool develops multiple inspection scheduling scenarios for comparison purposes. For example, you can use the planning tool to develop Time based inspection programme. After reviewing each scenario/programme, the user can select one of the scenarios/programmes as a final scenario/programme and update the actual/live inspection schedule. 

The inspection planning tool can be accessed via the inspection menu as shown below. 

This leads to the inspection scenarios list as shown below.

Click on the "Develop New Scheduling Scenario" button to create a new inspection planning scenario, as shown below

The planning tool automatically creates 4 scenarios, as explained below

An example output of the inspection schedule scenario is shown below.

5.4 Review inspection programme 

Click on the View link on the first column to review/export/modify a detailed inspection programme

To make manual adjustments/modifications right-click on the relevant inspection cell as shown below. 

Once the inspection programme is finalised/reviewed, click on the button "Add to/Set As Current/Final Inspection Programme", as highlighted in the image below, to set it as a final inspection programme. This function replaces the existing (future planned) inspection schedule with the selected programme. Please note that the current year's inspection programme will not be affected ie only the future/planned inspections are updated. 

The updated inspection schedule can be viewed using the "Inspections >> Current inspection schedule" menu item as shown below.

Risk-based inspection analysis is "dynamic analysis" and is driven by the condition of the structure and need. As new inspection data comes every year, it is important that the inspection programme is updated every year. So steps outlined in section 5 should be performed every year. 

BridgeStation risk-based analysis module automates the individual structure risk analysis using the process outlined in the LoBEG RBI Good practice guide. It also allows users to specify custom/user-defined intervals. It also helps compare the difference between time-based and risk-based inspection programmes. 

If the authority would like to implement its own analysis methodology on BridgeStation, Please contact BridgeStation support at ([email protected]) and we will help you out. The module can be configured to handle multiple analysis methods.