# Travel as Production — version history

## Version 1.1 — 11 July 2026

- Corrects terminology, boundary cases, proof conditions, cost definitions, and recent-literature positioning.
- Numerical exercises are now termed as illustrative.

Main clarifications:

- $T(a)$ is waiting time; queue stock requires a separate definition.
- Productive early arrival shifts a fixed-duration arrival window earlier: the early shoulder grows and the late shoulder contracts.
- The smooth-scheduling equality case is weakly FIFO and singular; below the threshold the displayed candidate is infeasible, and a replacement equilibrium is not characterised.
- The duration-dependent waiting-cost comparison now states its strict-ordering and baseline conditions.
- Traveller generalised cost, the model's queue-plus-schedule account, toll transfers, and unmodelled full welfare are distinguished.
- The literature discussion now places the contribution against recent activity-based bottleneck and in-vehicle time-use models.

## Version 1.0 — 26 June 2026

Initial public working-paper version, also posted to SSRN and issued as NTU Economic Growth Centre Working Paper 2026/03.