Another key milestone has been reach this in the ongoing refurbishment of Big Thunder Mountain Railroad at Magic Kingdom, as ride envelope testing got underway this week. Crews placed a ride envelope testing vehicle onto the track, along with a bright yellow test chassis, to begin evaluating clearance and safety tolerances along the newly installed sections of track.
Photos by @DCBaker
What Is Ride Envelope Testing?
Ride envelope testing is a critical step in the refurbishment process of any major attraction. The test vehicle—seen in the photo below—features rigid fins extending outward from its frame. These simulate the maximum reach of riders, ensuring that no part of the surrounding environment, rockwork, props, or structures falls within unsafe proximity to the ride path.
This process allows engineers to verify that all new track sections meet required clearance standards before further construction and theming are completed.
Yellow Test Chassis Spotted on the Track
In addition to the ride envelope vehicle, a yellow steel test chassis was also positioned on the track. These chassis units are typically used to assess weight loads, track alignment, and ride dynamics. Its presence today suggests that the retracked portions of Big Thunder are now entering the testing and verification phase of the refurbishment.
Refurbishment Progress So Far
Since the attraction closed on January 6, 2025, significant work has been completed, including:
- Full removal and replacement of track sections
- Installation of a new lift hill
- Ongoing work in the queue area, currently covered in construction tarps
- Set installation work filed by both Icarus Exhibits and Mecca Productions
- Multiple permits and Notices of Commencement extending into April 2026
The start of ride envelope testing is a clear sign that construction has reached a point where system validation and safety testing can begin. While this doesn’t indicate an imminent reopening, it does confirm that major structural work is nearing completion on key sections of the ride. Disney has said the ride will reopen in 2026, but has not given a more precise timeline.
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