Houston Transtar camera captured flames erupting into the air just after 5 a.m. on Monday.
The fires were near the Chimney Rock entrance ramp onto US-59. One ramp lane was closed.
The fires were in the cabs of two excavators, but no workers were present at the time.
The excavators are valued at $500,000 and are destroyed after being burned.
Investigators are working to find out how the fires started.
ABC13 reporter Jeff Ehling is on the scene.
This is a developing story. Stay with Eyewitness News for updates.
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