Mendip Quarries — Period 2 2026-27 (26 April – 23 May) report
Mendip Quarries handled 391 monitored inbound services and 384 monitored outbound services in Period 2 2026-27. Inbound arrivals read 80% within 15 minutes of schedule against a national freight benchmark of 90%; outbound services read 85% within 15 minutes. The +1 percentage-point move on Period 1 2026-27 inbound and the flat outbound sit within plausible sampling variation at these denominators; the ranges around each reading overlap. PRELIMINARY at T+2; FINAL re-publication at T+35 after Network Rail's batch correction.
- Edition
- v1.0 (industry review edition)
- Last updated
- 25 May 2026
- Next update
- Period 3 2026-27 — late June 2026
Headline facts and figures
Services monitored (inbound)
391
queried gauge_intelligence_v2 at 2026-05-25; 14 a day across the six Mendip tiplocs; Period 2 2026-27 (26 Apr – 23 May 2026); NROD-derived arrivals data; baseline 547 services in Period 1 2026-27
Within 15 minutes (inbound)
80%
queried gauge_intelligence_v2 at 2026-05-25; 313 of 391 completed inbound services arriving within 15 minutes of schedule (range 76–84% given the sample size); baseline 79% [76–82%] over 547 completed services in Period 1 2026-27 — ranges overlap; national freight benchmark 90% over 11,130 services in Period 2 2026-27
Services monitored (outbound)
384
queried gauge_intelligence_v2 at 2026-05-25; 14 a day across the six Mendip tiplocs; Period 2 2026-27 (26 Apr – 23 May 2026); NROD-derived departures data; baseline 542 services in Period 1 2026-27
Within 15 minutes (outbound)
85%
queried gauge_intelligence_v2 at 2026-05-25; 326 of 384 completed outbound services departing within 15 minutes of schedule (range 81–88% given the sample size); baseline 85% [82–88%] over 542 completed services in Period 1 2026-27 — ranges overlap; national freight benchmark 90% over 11,130 services in Period 2 2026-27
Context
ORR publishes aggregates only; this page publishes site-attributed supply-chain data with inbound and outbound directions reported separately. Material to bulk-flow planning, quarry siding allocation, and corridor performance reviews.
What you can do with it
- Track inbound arrivals and outbound departure reliability at a single supply-chain site.
- Compare operator-by-operator reliability on services to and from a quarry cluster.
- Cite the methodology in aggregates planning and corridor reviews.
Who can use it
Quarry operators · Aggregates planners · Rail journalists
Across Period 2 2026-27, roughly inbound trains a day arrived at Mendip Quarries more than 15 minutes late and roughly outbound trains a day departed more than 15 minutes late, across 390 completed inbound arrivals and 379 completed outbound departures over the 28-day period. Inbound within-15-minutes arrivals read — against 79% in Period 1 2026-27, a +1 percentage-point move; outbound read — against 85%, flat. The ranges around each reading overlap, so neither move clears the threshold for a defensible step change on this sample size. Monitored journeys fell from 547 inbound and 542 outbound in the baseline to 390 and 379 respectively, consistent with the May Day bank holiday weekend; counting journeys by site does not separate timetable change, traffic mix, or absent operators from underlying demand, and this report does not attribute the movement to a specific cause. Figures aggregate every monitored journey at the six Mendip tiplocs in Network Rail's NROD/TRUST feed. Cancellations are reported separately below.
Inbound — services arriving at Mendip Quarries
Operators at Mendip inbound
Freightliner Intermodal ran the most mendip inbound services in Period 2 2026-27 (206 of 390 completed arrivals). The full per-operator reliability comparison is deferred while the v1.0 industry review edition corrections inbox remains open.
Publishing a per-operator on-time comparison for the busiest freight operators at a single destination before the launch-cohort corrections cycle closes would treat provisional attribution as settled. The table returns at v2.0 general availability. The league-table methodology documents the comparison framework; the release cadence page sets out the four exit criteria for v2.0.
Source: Gauge Intelligence NROD-derived journey data, Period 2 2026-27. Single-destination headline figures (completed arrivals, aggregate within-15-minute rate, cancellations) continue to appear in the panels above; the per-operator breakdown is the panel deferred here.
What the 15-minute threshold hides
Half of Period 2 2026-27 services arrived early — the median was 1 min ahead of timetable. The long tail the A2F binary misses: 5% of services ran +47 min or more late, and 1% arrived over +117 min late. The 15-minute A2F threshold sits at the 80th percentile — 20% of services exceeded it.
Median arrival delay is 1 minutes later than Period 1 2026-27 (median was -2 min then, -1 min now).
| Percentile | Arrival delay |
|---|---|
| 50th percentile (median) — A2F threshold sits at the 80th percentile | -1 min |
| 75th percentile — A2F threshold sits at the 80th percentile | +12 min |
| 85th percentile | +22 min |
| 90th percentile | +32 min |
| 95th percentile | +47 min |
| 99th percentile | +117 min |
390 services with confirmed terminal arrival in Period 2 2026-27. A2F is binary at 15 minutes — this distribution surfaces what the headline figure does not show. National 99th percentile across all freight operators: 95 min.
Baseline (Period 1 2026-27): median -2 min, p99 +126 min. Period-on-period median shift +1 min.
ORR's Freight rail usage and performance release publishes by Network Rail region and route, not by operator. This page publishes by operator and corridor.
Cancellation rate
No scheduled paths or activated journeys recorded for Period 2 2026-27.
Outbound — services departing from Mendip Quarries
Operators at Mendip outbound
Freightliner Intermodal ran the most mendip outbound services in Period 2 2026-27 (233 of 379 completed arrivals). The full per-operator reliability comparison is deferred while the v1.0 industry review edition corrections inbox remains open.
Publishing a per-operator on-time comparison for the busiest freight operators at a single destination before the launch-cohort corrections cycle closes would treat provisional attribution as settled. The table returns at v2.0 general availability. The league-table methodology documents the comparison framework; the release cadence page sets out the four exit criteria for v2.0.
Source: Gauge Intelligence NROD-derived journey data, Period 2 2026-27. Single-destination headline figures (completed arrivals, aggregate within-15-minute rate, cancellations) continue to appear in the panels above; the per-operator breakdown is the panel deferred here.
What the 15-minute threshold hides
Half of Period 2 2026-27 services arrived on time or better. The long tail the A2F binary misses: 5% of services ran +48 min or more late, and 1% arrived over +122 min late. The 15-minute A2F threshold sits at the 86th percentile — 15% of services exceeded it.
Median arrival delay is essentially unchanged on Period 1 2026-27 (0 min then, 0 min now).
| Percentile | Arrival delay |
|---|---|
| 50th percentile (median) — A2F threshold sits at the 86th percentile | +0 min |
| 75th percentile — A2F threshold sits at the 86th percentile | +6 min |
| 85th percentile — A2F threshold sits at the 86th percentile | +14 min |
| 90th percentile | +24 min |
| 95th percentile | +48 min |
| 99th percentile | +122 min |
379 services with confirmed terminal arrival in Period 2 2026-27. A2F is binary at 15 minutes — this distribution surfaces what the headline figure does not show. National 99th percentile across all freight operators: 95 min.
Baseline (Period 1 2026-27): median +0 min, p99 +92 min. Period-on-period median shift +0 min.
ORR's Freight rail usage and performance release publishes by Network Rail region and route, not by operator. This page publishes by operator and corridor.
Cancellation rate
No scheduled paths or activated journeys recorded for Period 2 2026-27.
What this report doesn't yet carry
Four blocks routinely carried on more mature period reports remain absent, and the gap is disclosed rather than papered over:
- Partial-pool operator league table. The supply-chain artefact track is not yet wired into the archive renderer — the partial-pool, median-polish, statistical process control (SPC), and compositional log-ratio panels do not yet emit for supply-chain sites. Inbound and outbound flows at a quarry cluster behave as two distinct populations and the partial-pool shrinkage assumption needs separate calibration for each direction. The block is suppressed pending that calibration.
- SPC process-behaviour chart. Mendip has eight weekly A2F (arrivals-to-fifteen-minutes) points per direction across Period 1 and Period 2 2026-27 combined. The signal rules require eight before a stability or anomaly claim can be made — the threshold is now met; the chart enters as a candidate from Period 3 2026-27 once the baseline survives one more period without composition change.
- Median-polish operator-by-week matrix. The row-by-column operator-by-week decomposition requires a minimum number of journeys per weekly cell for each operator present. At this baseline depth the matrix is not yet sufficiently populated to publish without degeneracy. The block is suppressed.
- Compositional delay-reason breakdown. Network Rail's Historic Delay Attribution (HDA) feed for Period 2 2026-27 has not been imported at the as-of date of this report. Raw percentage-share comparison is misleading when shares are constrained to sum to 100% — an increase in any one cause forces a decrease in another — so the block is suppressed rather than substituted with a naked share. See the delay-attribution methodology.
Each of these unlocks as baseline depth grows. The weekly SPC threshold is met from Period 3 2026-27; the operator-by-week matrix and HDA breakdown become candidates as the trailing window deepens through 2026-27.
Methodology & sources
All figures derive from Network Rail's NROD TRUST feed, processed via the Gauge Intelligence ingest pipeline. Period definitions, A2F (Arrival to Fifteen), the Wilson 90% interval, daily anomaly rules, cross-view reconciliation, and delay attribution are documented at:
Data window — period boundaries and the data-as-of cutoff
League tables — cross-view reconciliation across the four analytical views
Anomaly detection — daily A2F SPC rules
Delay attribution — DAPR cause-code breakdown
Forecasting — prediction intervals and possession-exposure estimates
Three further reads sit behind the commercial licence: a Schedule 8 net-position figure netting the FOC-to-Network-Rail differential against payments the other way; a full Delay Attribution Performance Report breakdown attributing each cause-code's contribution by sample weight; and a Schedule 4 possession-exposure read tracing how planned blockades intersect quarry-bound path allocation. None is yet substantively informative at Mendip's current baseline depth — the period count that suppresses the SPC chart above leaves each licensed read with too few points to anchor. The licensed access page sets out the methodology behind each.
Revisions
No revisions to date.
A revision restates a published figure because the upstream data changed, typically a Network Rail delay-attribution refresh. The minor tier is corrected in the next release; cells affected carry an (r) flag. The intermediate tier triggers immediate amendment with an (r) flag. The wholesale tier is flagged at the top of the page and notified directly to operators and rail journalists subscribed to revision alerts.
Corrections
No corrections to date.
A correction fixes an error in the published output: an arithmetic slip, a typo, a mis-rendered chart. Revisions are different; they restate a figure because the upstream data changed. The distinction matters because corrections never silently rewrite a published number.