The schedule said go, and the work package looked ready on paper. Then the piping crew arrived and found the steel supports underneath still unfinished. On capital projects, out-of-sequence work like this leaves crews standing idle, forces rework and drives up labor costs.
ONBuild, O3's workface planning software for construction execution, helps prevent out-of-sequence work by using 3D model data to put Installation Work Packages (IWPs) in the order the work can be built. O3's latest release adds What If scenarios to ONBuild's IWP sequencing, so teams can test staffing changes before anyone commits a crew.
On many projects, teams review the model by hand to find the predecessor work each package needs before it can go to the field: which foundations support which steel, and which steel carries which pipe supports. With thousands of components across multiple disciplines on a large project, tracking those dependencies manually is slow and error-prone.
Staffing decisions in the weekly lookahead meeting run into the same manual work. When the finish date slips, someone asks whether adding crews would recover the lost time. Answering that question by hand means reworking durations and pushing new dates through the package sequence. Teams then need to check whether the extra crews would find work ready to start or end up waiting on the same constrained packages as everyone else. Running those numbers in a spreadsheet takes a lot of time, so the decision is often made on instinct. When the instinct is wrong, projects pay for crews that have no work ready.
O3 reads the model to understand where components need to be installed before each other (such as Pipe sitting on pipe supports sitting on steel sitting on foundations sitting on piling) to make sure any planned sequence is truly constructible.
When teams create or review an IWP, they see the predecessor work that must be complete before the package can start. If a steel erection IWP depends on a foundation that's only 60% done, O3 flags the package. Construction managers and superintendents can then trust that the packages reaching the field are ready to build. Fewer crews sit idle, rework drops and more hours at the workface are productive.
The sequencer levels crew capacity and holds work for open constraints and material arrivals. Teams review and adjust the proposed sequence on the Gantt, and the plan stays unchanged until a team applies a run. The sequence draws on current model and constraint data, so the team can rerun it whenever site conditions change instead of updating a P6 schedule or spreadsheet by hand.
The Sequence IWPs view lays the proposed IWP order out on the Gantt, grouped by construction work area, construction work package and discipline, for teams to review before saving.
With this release, teams access the IWP sequence optimizer and add one or more scenarios. Each scenario can test:
A scenario can apply to every IWP in the lookahead or only to one discipline or purpose. O3 runs each scenario against a baseline, labeled Current Optimized Sequence, so every result is compared with the plan the team is already working to. Each scenario shows what is at stake: more or less budget, more or less hours and the impact to schedule. If a scenario changes nothing, for example extra crews for a discipline that has no crews, O3 shows a warning instead of a misleading result.
The Summary tab scores four key measures against the plan and against the baseline: projected finish, peak headcount, crew utilization and projected manhours. A score radar and weekly headcount charts by discipline or purpose show where each scenario adds people. An outliers list points to the packages that behave differently from the rest.
A written narrative explains the run in plain language, including why some changes would not help. Suggestion chips point to changes that have been tested to pull in the finish date.
The Scenarios tab lays every run side by side in a scenario matrix, marks the best run and gives every run its own Apply button. The What Shifted tab compares the previous and new dates for each IWP and lists the moved packages first, so teams can see exactly which work changed. Capacity delays are counted in working days and charged to the crew pool that actually blocked each IWP, so the report shows where the real bottleneck sits.
Teams can answer the extra-crew question during the lookahead meeting instead of afterward. A team can show that a second piping crew finishes the area a week earlier, or that the second crew would wait on the same scaffolding constraint as the first. The team then decides on evidence instead of instinct.
Construction managers can weigh crew requests against the work available in the sequence. Peak headcount and crew utilization show whether an extra crew has steady work or only fills a gap for a few days. That difference matters when labor is scarce and mobilizing a crew carries real cost.
For project controls teams, projected manhours and the finish date sit side by side, so the labor needed to recover schedule is visible before anyone approves a plan. Exporting the results creates a PDF management report that project managers can share with leadership or with the Owner when a recovery plan needs sign-off.
Object Relations, IWP Sequencing and What If scenarios extend the planning tools teams already use in O3, including automated IWP creation for stick-build projects and piping. The IWP lookahead shows planned and remaining hours by day, the O3 Sequencer proposes the installation order and weekly work plans commit crews to specific IWPs. Scenarios add a step between the proposed sequence and the committed plan, where the team tests staffing and productivity changes before locking anything in. Once crews finish the work, every package flows into ONComplete, O3's systems completions and turnover solution.
Teams spend less time on manual dependency checks and more time on coordination and constraint removal. Field crews meet fewer surprises at their work areas, superintendents can trust the packages in their queue, and project leadership gets a report on the finish date and projected manhours for each recovery option. Experienced teams still make the call, with better information in front of them.
To see how IWP sequencing and What If scenarios could support optimizing execution on your next project, request a personalized demo.