The Transport Module is a type of transportation when the Technodrome was farther away from New York.
The Transport Modules are the vehicles used by Krang, Shredder, Bebop and Rocksteady to move from the Technodrome to New York when the Technodrome is located on the Earth. Although they are best known in their underground drill form, their physical make-up actually changed as the Technodrome moved, such as adding a propeller and fins to the body when the Technodrome was underwater.
With the Technodrome located in the Earth's core during most of season 3, the first of the more famous type of transport modules are used. It looks similar to a space shuttle without wings and with a drill in the front. Even Bebop and Rocksteady are able to pilot these transport modules.
Season 5 (1991)
After energizing the Technodrome with a giant electromagnet, Shredder and Krang were able to bring it back to Earth from Dimension X, but alterations by Donatello caused the Technodrome to land in the middle of the Arctic. With the Technodrome located in the North Pole during most of season 5, the transport modules from season 3 are used once again, this time to drill under the North American continent and towards New York City.
Later, Krang utilizes a laser from outer space to melt the Technodrome free of the ice, and the Turtles are powerless to stop it. Fortunately, Bebop and Rocksteady cause the controls of the laser to malfunction, resulting in the Technodrome ending up at the bottom of the Arctic Ocean. Once again, these transport modules are used to travel from underwater and into the city.
Season 6 & 7 (1992-1993)
After Krang and Shredder steal an anti-gravity device and make the Technodrome capable of flight, the Turtles disabled it, resulting in the Technodrome being trapped at the bottom of the ocean once again, this time near New York Harbor. With the Technodrome located under the Arctic Ocean during season 6 and season 7, the amphibious modules - retooled underwater types of transport modules - are used to get to the city faster than before.