Second build · the worked example

Can I get off the island, and can my car.

There is no bridge. Every crossing is a boat, and your car may not fit on today's. The second twin answers both on one page. Every number names its file. Every blank gives a date. The crossing is one worked example of the method.

Copernicus Sentinel-2, 13 July 2026 · sources

The front page

Eight panels, twenty-eight values.

The second build's front page. Eight panels of rows. Each value tagged KNOWN or MODELLED, each blank dated, the TransLink line at the foot. — Captured 2 September 2026. Island clock 00:00, Friday 21 August 2026. Nothing altered.

A digital twin is a working model of a real place that says where each number came from. Each row: a label, a value, a chip, a file on disk.

Sailing times come from SeaLink's timetables and the Gold Cats Flyer sign, supplied 19 August 2026. Bus times come from TransLink's island feed. Every blank says why it is blank.

panels

tools/panels/front.json

values, each pointing at a file

docs/STATE-OF-PLAY.md, 20 August 2026

services, 2 operators, 2 jetties

data/crossings.json

sailings in the pack, all sealed

docs/STATE-OF-PLAY.md

Panel by panel

What each panel answers

A pack is a data file the twin reads. Crossings pack: two operators' timetables and the departure sign. Bus pack: TransLink's island feed. Tide pack: no tide table, and it says so.

Known

Quandamooka Country

The acknowledgement of Country comes up as the page loads, out of the lore pack. No menu hides it. A rule checks the wording word for word.

ModelledKnown

Getting off the island right now

Three rows. The island minute, MODELLED, off the twin's clock. Then on foot, and with a car. Each answers yes, not yet with the first time, or no with the last. Crossings pack.

Known

Leaving on foot

The next boat off and the last boat off today. SeaLink goes from Junner Street, the Gold Cats Flyer from One Mile. On foot you have two ways off. A car has one. Crossings pack.

KnownNot known

Getting your car off

The next vehicle sailing and the last one today, or tomorrow morning if it has gone. Room for your car is a dated blank: nobody knows yet whether you book or queue. Crossings pack.

Known

The hours a car cannot leave

Four rows off four times. The morning gap before the first vehicle sailing, the evening gap after the last, the whole day, and where this minute sits. Crossings pack.

Known

The two jetties and the buses

For each jetty: the next boat off, the bus that meets it, boats in and out today. On the captured Friday, 48 at Junner Street and 28 at One Mile, never added. Bus week 19 to 25 August 2026, a school term. Crossings and bus packs.

Known

Each service on its own

One row per service, built from the pack, so a fourth turns up the day it lands. SeaLink's vehicle barge and passenger ferry from Junner Street, the Gold Cats Flyer from One Mile. Lose one and the note says "it takes one end off it." Crossings pack.

Not known

What the twin does not know

Six rows, five blank on purpose. Water level at the jetties (tide pack, MODELLED). Public holidays. Extra vehicle sailings. School holiday changes. Walk-on crossing time. The sixth asks whether the red-printed Gold Cats Flyer times change today's answer.

The chips

Known, modelled and dated blanks

A record can make four kinds of claim: known, modelled, proposed and contributed. Two turn up here.

Known Read off a timetable, a sign or a feed. The next boat and the last vehicle sailing are KNOWN.

Modelled The twin worked it out. The minute at the top comes off its own clock.

Not known When the twin is not sure, it prints "contested or unknown" with a date and no number. The date is when it last looked. Timetable blanks show 19 August 2026. The water level shows 21 August 2026, the island day on the clock.

A checker runs over the page. On 20 August 2026 it passed 10 rules over 8 panels and 28 values, two minutes into the island day.

The two-crossings rule

Cars and people are never added

The crossings pack states its own rule: "you can almost always get off the island; you cannot always get your car off." Every service and sailing is tagged vehicles or passengers, never both. No field adds cars to passengers. A vehicle sailing takes people too, and the pack refuses the sum.

Known

Five hours a day

The walk-on day runs 05:15 to 20:45, seven days a week. The vehicle day runs 07:00 to 17:30. That leaves 1 hour 45 minutes in the morning and 3 hours 15 minutes at night. Five hours a day when a person can leave and a car cannot.

A floor

The vehicle timetable is a floor

SeaLink calls its vehicle timetable a base and adds sailings as required. Those extras show only on its booking page. The pack has the ten printed departures each way. A count from this build is a floor, so the extra-sailings row is a dated blank.

Each vessel record keeps cars and deck passengers as two named fields with no total. Three faults tested the rule: a summed figure, a count with no source, and a boat declared to take both.

The foot of the page

The licence line at the foot

GTFS is a file format for published timetables. TransLink publishes one for the island's buses, two routes and 44 stops. Its stops include Junner St Ferry Terminal (Dunwich) and Yabby St at One Mile Ferry Terminal. The feed is CC BY 4.0: free to reuse if you credit the source and say you changed it. The page prints it at the foot, out of the bus pack:

"Contains public sector information licensed under Creative Commons Attribution 4.0. Source: Department of Transport and Main Roads, Translink Division, General Transit Feed Specification (GTFS) data, published at data.qld.gov.au. Retrieved 19 August 2026. Changes were made: figures here are counted, joined across files and filtered to this island, and are not the publisher's own published figures."

TransLink names a stop, the operators name a jetty, and the two share no id. A second line says why stop 870029 is Junner Street and 870027 One Mile. Nobody has measured the walk from stop to boat. A bus one minute before a sailing is printed as one minute before.

No boat is tracked

The timetable and the island clock

The first panel says: "no boat here is being tracked." Behind every time is an operator with a web page and a sign at a jetty. A row changes when a person reads one again and posts it. The 19 August 2026 timetable is sealed, and a changed time stops the build.

The island clock ticks once a minute, and the page names the minute its answers are for. It checks itself every frame. If the minute or the next departure disagrees with the timetable, the page says so on itself.

A live boat position would beat a printed timetable. TransLink publishes a live bus feed and nobody has wired it up. Neither boat operator publishes one.

Open it: the live page and the repository. Inside the second build covers the record, the ladder and the gate. Open them yourself has the one command for your machine.