Construction scheduling and trade interfaces · Lesson 3 of 4

Construction scheduling and trade interfaces: methods and worked application

A seven-step method, then a parapet flashing worked through the forward and backward pass, one resubmittal, constraint screening, inspection holds and the AFS delivery day.

You will be able to: Build a documented interface schedule for a flashing scope, with owners, hand-off conditions, a forward and backward pass, constraints and inspection holds, recording every assumption and unit.

12 min · 12 slides · 7 questions

All lessons in this module

Slide 1 of 12

The method in seven steps

This module’s own method, drawn from the GAO guide and the Last Planner summary.

1 List the interfaces.
2 Name an owner for each layer.
3 Write each hand-off condition so it is observable.
4 Add the paper and shop chain as activities.
5 Link, run both passes, read the float.
6 Screen each task for constraints.
7 Put inspection holds in the weekly plan.

Sources

GAO-16-89G Schedule Assessment Guide: Best Practices for Project Schedules (December 2015) - U.S. Government Accountability Office
Last Planner System: Just the Essentials (copyright 2005, 2011) - Lean Project Consulting, Inc. (Last Planner is a registered trademark of the Lean Construction Institute)

Glossary

Forward pass: The calculation that finds each activity’s early start and early finish by adding durations through the network from the first day.
Backward pass: The calculation that finds each activity’s late start and late finish by subtracting durations, working back from the project end date. Float is the difference between early and late dates.
Make-ready plan: In the Last Planner method, a six-week look-ahead in which tasks are screened for constraints so that work is ready before it is assigned.
Weekly work plan: In the Last Planner method, the plan for the coming week, which should hold only work that is ready to be performed and includes inspection tasks required before the next crew begins.
Conditions of satisfaction: In the Last Planner method, a statement of exactly what will be in place and observable when a work item is complete, for example which specific walls will be finished.
Constraint log: In the Last Planner method, the record of open constraints. Each entry carries the need date and the promised date, and its status runs from negotiation to promised, in progress and complete.