> For the complete documentation index, see [llms.txt](https://changelog.visilean.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://changelog.visilean.com/changelog/release-3.0-2026/baseline-dates-selection-in-bim.md). # Baseline Dates Selection in BIM Construction projects rarely run against a single baseline. By the time a project reaches mid-stage, there may be an original contract baseline, a post-variation-order revision, and a recovery schedule baseline each capturing a different point-in-time snapshot of the programme. Until now, activating Planned vs. Actual mode in the 3D BIM Viewer locked you into a single, hard-coded planned state with no way to choose which baseline drove the "Planned" side of the comparison. The 4D BIM Viewer offered only two fixed options Planned and Actual dates with no baseline awareness at all. #### Why This Matters Comparing actuals against the wrong baseline produces misleading deviation data. On a project with approved variation orders or a re-baselined schedule, showing progress against the original contract baseline when the team is working to a recovery programme makes the deviation numbers meaningless or worse, actively misleading. Incorrect baselines feed into flawed progress claims, erroneous delay analysis, and decisions made on data that doesn't reflect the contractual or operational reality. Planning engineers and project managers need to interrogate deviations against a specific baseline, not whichever one the system happens to default to. #### What's New? * **Baseline dropdown in 3D BIM P vs A mode:** In the Planned vs. Actual mode, a dropdown appears on the Planned side listing all named baselines saved against the project (e.g. "Baseline 1 - Original Contract (01 Jan 2024)", "Baseline 2 - VO-3 Revision (15 Apr 2024)"). Select a baseline and the Planned side re-renders immediately to reflect that baseline's model state as per schedule data. * **Baseline option in 4D BIM date selector:** The existing date selector previously limited to "Planned" and "Actual" now includes a Baselines group listing all saved project baselines. Selecting one drives the 4D timeline animation from that baseline's start and end dates. * **Single-select, session-scoped:** One baseline at a time, clearly labelled on screen, so there's no ambiguity about what the visualisation is showing. #### How It Helps A *Planning Engineer* preparing for a monthly progress review activates P vs A mode in the 3D BIM Viewer and selects the post-variation-order baseline from the dropdown. The Planned side now reflects the revised programme not the original contract dates so the deviation visualisation accurately shows where work is ahead or behind against the schedule the team is actually working to. The baseline label on screen confirms exactly which snapshot is being compared, and the engineer walks into the review with data that matches the contractual position. A *Project Manager* conducting a delay analysis selects the original contract baseline in the 3D BIM Viewer to quantify total drift from the initial programme, then switches to the recovery baseline to assess whether the recovery plan is being achieved. Both comparisons take seconds no export, no separate tool, no manual overlay. The visual evidence goes straight into the delay report. A *BIM Coordinator* setting up a 4D simulation for a client presentation selects the approved baseline in the 4D date selector. The timeline animation now shows the planned construction sequence as the client's contract defines it, with actuals overlaid. The client sees exactly how site progress compares to the agreed programme, milestone by milestone, in a format that needs no explanation. --- # Agent Instructions This documentation is published with GitBook. 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