Owner's Ex4 method for irregular lines — read trips at core points over the whole day, find the repeating interval, split destination variants onto longer offset intervals
On 20 Oct 2026, on the Havířov/Karviná/Orlová sheet, the owner said: "Look at how I did in the save game Ex4 - there is also a very irregular service, but I defined it in core points, created a repeating interval and it suddenly made sense." In the save, Ex4/1 runs every 240, and Ex4/2 and Ex4/3 every 480, one line per destination. Each is timetabled only at core points (the termini, Bohumín, Břeclav).
Scope: regional lines and small-town networks (Havířov, Karviná, Orlová); not Ostrava, Prague, Olomouc (see regional-vs-local-rules).
Why: a fit made only on the afternoon band, by terminus pair, makes irregular lines look random. Read at core points over the whole day, they usually repeat. The Orlová 501/504 turned out to be one hourly bus: Lazy :06, Dětmarovice, železniční stanice :18.
How to apply:
Take each trip's time at the core points it passes, not its start or end.
Read the whole operating day.
Choose the repeating interval.
Give each destination variant its own Simutrans line on a longer interval (240/480), offset so the lines don't coincide. The owner also accepts merging a sparse line into another as one of its legs, for example 503 as 504's path variant.
Time only the core points, and name the trips that don't fit.
Buses differ from trains (owner, 20 Oct): time the terminal and work back from the knot. Terminal departure = knot time − running time; the knot gets no timetable. 501B leaves Koukolná :09 to pass the station :18; 406 leaves Pašůvka :26 / :56.
No daily lines (owner, 20 Oct): "8 hrs should be the very maximal interval (still not preferred) … we can bend the reality a bit." Never use 1440 or 720. Bend sparse trips onto a repeating slot of at most 480: the interval they already have (shift lines every 480; 420's trips 160 apart), a circuit on the shortest period that holds a one-bus sequence (418 every 240), or fold them into the line they belong to (513 on 514).
The full step-by-step method for any model is pipeline/bus-schedule-method.md. Reference: pipeline/havirov-karvina-orlova/README.md, section "Core points". Related: hand-review-schedules-rule, every-stop-covered-rule, simutrans-fork-schedule-spec.