NASA's crawler-transporter is a tracked machine the size of a baseball infield. It carries rockets from the Vehicle Assembly Building at Kennedy Space Center to the launch pad.

It was built in 1965 to move the Saturn V along that route.

When they were built, these were the largest tracked machines ever made.

The excavator Bagger 288 later surpassed them.

The weight record stayed put.

On March 29, 2023, Guinness World Records named CT-2 the heaviest self-powered vehicle.

Its listed weight is about 6.65 million pounds (3,016 metric tonnes).

Loaded, it moves at 1 mph (1.6 km/h) at most.

One trip takes about five hours.

Why not faster?

The rocket has to stay vertical.

A laser system guides the crawler. A leveling system keeps the platform level to within about 1 foot (30 centimeters) at the top of the Saturn V, while the machine climbs a 5% grade. Locomotive engines and large electric generators drive it.

After upgrades, it stands ready for the next generation of rockets.

It crawls because the cargo is a rocket.
That is why it is the heaviest machine that moves itself.