Investigation into Network Rail's risk modelling, embedded risk and uncertainty on PR23

The ORR has recently begun its 2023 periodic review of Network Rail covering the five years from April 2024 to March 2029. A central element of every periodic review is a cost assessment whereby ORR determines the appropriate level of expenditure required to deliver the outputs set by funders.

The System Cost & Efficiency team is part of the Capital Investment, Enhancements, Engineering and Asset Management team in ORR and is focussed on achieving an efficient cost assessment as part of the PR23 process.

Network Rail delivered round 4.5 of its plan to ORR in Mar 22. This was the final top-down plan and Network Rail has now moved to round 5.0, the first stage of bottom-up planning. ORR will not receive this plan, but wishes to gain confidence that risk and uncertainty is adequately considered as part of Network Rail plans and therefore wishes to commission a study into the methodology used within Network Rail to develop its P(50) plan.

Currently an Independent Reporter piece of work is being conducted into the use of unit rates within Network Rail, an overview is shown below. The output from the Independent Reporter, when combined with the outputs described in section 2.3 will provide ORR with a holistic view of risk inherent within Network Rail planning processes.

Independent reporter: How are unit cost rates calculated and used

Background: Unit rates, when combined with the volumes of work to be undertaken, provide the key costing information for the renewals plan. Local and national rates often exist, their selection criteria is not always documented in Network Rail's Initial Business Plan (IBP) and their limitations / applicability need to be understood.

Why is this an issue: Unit rates are a key cost driver. Appropriate selection is imperative, national rates should be the composite average, as such, local rates, when combined should average out at the national rate. Should a more advantageous rate be selected for planning purposes additional (excessive) risk provision would be embedded in estimates.

Plan to address: Independent Reporter commissioned

What does "good" look like as an outcome for ORR: Clear understanding of the statistical significance of local / national unit rates and their applicability / selection criteria. An understanding of the adherence to these criteria, allows a quantitative view of embedded risk.

Additional information: The tender exercise is being managed via the ORR Procurement portal (BRAVO). All tender clarification questions must be raised via the portal.