Linear Scheduling Methods (LSM)

What linear scheduling is

It goes by several names — time-location chart, line of balance (LOB), linear scheduling, or location-based scheduling. They share one core idea: when work repeats along a line or through identical units, the most revealing axis isn't just time — it's where each crew is, when.

The time-location chart

The chart has time on one axis and location (chainage, station, floor, unit) on the other. Each crew's activity is a line travelling across both. Its slope is its production rate — steeper means faster (more location covered per unit time).

Reading slopes, gaps, and crossings

1. Slope = production rate — steeper line = faster crew (more location per unit time). Parallel lines = crews moving at the same pace, keeping a constant buffer.
2. The gap = the buffer — the vertical (location) or horizontal (time) distance between two activity lines is the working buffer between crews. You want to keep it positive and comfortable.
3. Converging lines = trouble — if a following crew is faster than the one ahead, the lines converge — the buffer shrinks to zero and the crews collide. Fix it by re-pacing, resequencing, or adding a buffer.
4. Flat spots = stoppages — a horizontal segment means time passing with no location gained — an interruption. A vertical jump means location with no time — usually a discontinuity to investigate.

LSM and CPM together

Linear scheduling doesn't replace CPM — it complements it. CPM excels at complex, non-repetitive networks with rich logic; LSM excels at showing flow and location on repetitive work. Many linear projects use both: a CPM for the overall logic and milestones, and a time-location view for the repetitive production crews.

Ten things to remember

1. Linear scheduling plots time vs. location — built for linear/repetitive work.
2. Also called time-location chart, line of balance, location-based scheduling.
3. Use it for roads, rail, pipelines, tunnels, transmission lines, repetitive floors.
4. Slope = production rate — steeper is faster; parallel lines hold a constant buffer.
5. The gap between lines is the buffer — keep it positive and comfortable.
6. Converging lines = crew conflict — re-pace, resequence, or add a buffer.
7. Flat spots = stoppages — time passing with no location gained.
8. The goal is continuous, balanced flow — steady rates, protected buffers, no start-stop.
9. LSM complements CPM, not replaces it — many linear projects use both.
10. Linear schedules still have a controlling path — criticality applies through flow.