Triggers & thresholds
The numeric rules that drive autumn decision-making. The dashboard evaluates the GBW and GSM-R triggers automatically from the incident log.
GBW area trigger >2 in 7 days
- More than 2 high-risk WSTCFs in 7 days in the same GBW area, attributed or likely leaf fall → special working at ALL high-risk sites in that area.
- NOC issues the Leaf Fall Alert.
- Exemptions where the area has no high-risk sites or all sites are RCM-monitored (NOC advised).
- EM GBW areas: Bedford, Derby East, Derby West, EM Lincoln North, Boston, Allington, Swinderby East, Swinderby West, Gainsborough (+ Leicester). Swinderby East TCs are numbers, West are letters.
GSM-R acknowledged broadcast 2+ ROLAs / 3h
- Trigger: 2 or more ROLAs at the same location within 3 hours.
- Cell broadcast to trains in the area using the scripted safety message.
High-risk WSTCF site definition ≥2 / 3 yrs
- 2 or more WSTCFs caused by contamination within 3 years (NR/L2/OPS/095).
- 2026 EM list: 25 track circuits on the main list plus 14 on the supplementary list (39 in total, Appendix B of the 2026 guidance).
- New for 2026: Havenhouse AT (GRS4), Burton Joyce Station YHL and Trent Lane UWC YHG (NOB1). Every site that was 'New' in 2025 is now 'Remaining'.
Low-adhesion high-risk site definition SPADs / overruns / veg
- More than 2 SPADs in 3 years, OR
- More than 4 station overruns in 3 years, OR
- Score above 26 on NR/L2/OTK/5201/F3076 (vegetation), OR
- Significant stakeholder concern.
- 14 sites for 2026 (Appendix N): 2 new — Ambergate Jn – Matlock (LN3246, AJM1) and Colwick LC (LN3625, NOB1); Kirkby in Ashfield Station has dropped off the list.
30-minute rule (TW1 §28.2) Controlled test stop
- A controlled test stop may be made when: the site has been inspected and nothing found; OR inspected and treated; OR a further 30 minutes have elapsed.
- The test must be made by a vehicle of the same class as the one that reported.
- Never approach a dead-end platform until the site has been treated.
Interflon 90-minute rule 90 min
- Driver reports low adhesion within 90 minutes of an Interflon treatment → apply TW1 §28.2 and the 30-minute rule.
- Interflon CleanRail: 1–2 minute activation, residual protection up to 25 days, never applied on points.
- Schedule: Friday nights PBS3 Mansfield, SSJ1 Chellaston, PMJ Manton, NOB1 Newark; Sunday nights NOB3 Reepham/Cherry Willingham, GRS2 Sudbrook, SPD3 West Holmes/Slaughterhouse.
Missed-site definition Wire or not
- RHTT fault, or access blocked by an infrastructure failure / unplanned possession → MISSED SITE: issue the missed-sites wire and arrange staff attendance even if later treated.
- Pre-planned WON possession → NOT a missed site: no wire; staff inspect/treat high-risk junctions instead.
Cold weather −5°C
- Below −5°C, contact the SCO before water jetting (RHTT jets at 1500 bar).
- RHTT consist: top-and-tail locos, 2 flat wagons, water + adhesion modifier.
Season extension criteria 7 criteria
- Seven criteria assessed, including: black/red adhesion days still occurring; less than 90% of leaves down; more than 12 ROLAs per line per week; adverse KPI trend.
- Extension request to the SCO before the end of November; Operations Director approval required.
Early cessation criteria Mirror
- More than 90% of leaves down;
- 12 or fewer ROLAs per line per week;
- No autumn KPIs in the preceding week.
- Mirrors the extension criteria; Operations Director approval required.
TGA inspection cadence 7 / 14 days
- 25 TGA sites for 2026 (Newstead on the RAC added, Trowell Jn removed); commissioned in September by MOM teams, operational by 1 October.
- Inspect 7 days after commissioning, then every 14 days.
- Faults reported to Autumn Control (defective TGAs listed on wires and the log).
Track-section boundary transition (clause 3.13) <1 s
- A blip under 1 second while either abutting TC remains occupied is not a WSF — the interlocking is assumed not to have reacted; classify Negligible.
- Treat it as a possible early indication of a WSF: assess and action (proactive treatment, slow RHTT pass).
Level crossings — AHB overlay & ABCL/AOCL No Reg 3.5 / L2
- AHB crossings on overlay DC track circuits whose interlocking runs on axle counters / absolute block: an RCM alarm does not need Reg 3.5 — the sequence is backed up by strike-in treadles. Do a crossing sequence check after any RADAR alarm; signallers monitor 'Barriers working' and Centrix 'Barriers failed' alarms.
- ABCL / AOCL crossings with TCs inside the crossing: a failure is a Low-risk Level 2 fault but special working is still required; FMS raised Low, wheelset exam within 30 minutes, CCIL created.
Railhead contamination levels L2 / L3
- Level 2: running band barely visible, patchy black — treat unless no possibility of a blockage.
- Level 3: thick continuous black, no running band visible — treatment essential.
Adhesion index scale (MetDesk, 0–10) 0–10
- 0–2 Good · 3 Wet railhead / damp · 4–5 Moderate · 6–8 Poor · 9–10 Very poor.
- Forecast issued daily by 03:00 (to 06:00 next day) with a 2–5 day outlook; black forecast → EWAT convened; red/black → Reg 3.5 reinstated at relevant sites.