FasTrack Length Calculator

Inputs

The target length: whole inches plus a fraction in eighths, from 1 3/8 in (the shortest section made) to 100 in. FasTrack is an imperial system and its published lengths land on 1/8-inch steps, so this calculator works in exact eighths and shows no metric.

Method

The seven straight-section lengths are facts from the LCCA's “FasTrack Table of Lengths” by Bill Schmeelk³. Combinations on this page are computed independently by this calculator.

All arithmetic runs in integer eighths. A dynamic programme first finds the minimum number of sections for every reachable length up to 800 eighths (100 in), the 30 in section included:

A solvable target is then expanded into every distinct combination that uses that minimum count, taking sections largest-first so each combination appears once, in the order shown. Up to 8 combinations are drawn; past that a line reports how many more exist. An unsolvable target — only possible below 5 3/4 in — reports the nearest solvable lengths below and above, then the removal helper: for each section size, if removing one from track already laid makes the gap solvable, it says what to fill the new gap with (at most 3 rows). That remove-one-section technique is credited to the LCCA article³; the fills are this calculator's own.

Rounding

Nothing rounds. Every length is an exact integer count of eighths of an inch, and results display as reduced fractions written with a solidus (12 3/4 in), never decimals.

Limitations

• Assembled track has joint tolerances — check the final fit on the board before you fix anything down.
• This calculator deals in straight sections only; curves are a different problem.
• This is a planning aid, not an engineering or safety certification.

Worked example

FT-1: a target of 12 3/4 in is 102 eighths. The table gives min[102] = 3 sections, and the expansion finds exactly one three-section combination: 1 × 10 in + 2 × 1 3/8 in (80 + 11 + 11 = 102 eighths). This is the reading shown in the result panel until you solve your own.

Sources

The LCCA article³ is credited for the seven section lengths and the remove-one-section technique, and for the statement that every length above 5 5/8 in is achievable — which this calculator's tests verify independently across the whole range it solves. Its tables and chart are not reproduced here. The full reference is in the ledger below and on the sources page.