Groundbridge

A scaled-down iteration of space bridge technology, a GroundBridge allows transport to coordinates on a single planet, or even into the planet's orbit. Considerably easier to maintain and less costly in energon to operate, it is the primary means of coordinating Autobot forces on planet Earth. Most tellingly, GroundBridge technology requires no receiving terminal at the destination in order to function.

Ficiton
When Cliffjumper called for backup, Autobot reinforcements converged on his location via GroundBridge. When Cliffjumper's life signs were later detected by the computers in the Autobot base, the team likewise departed via GroundBridge to investigate. Ratchet was left behind to mind the Autobots' human guests, and explained to them that the team did not have the means to maintain a full space bridge, nor the energon to power such. As a result, they relied heavily on GroundBridge technology to dispatch the team to deal with alerts. Travel through the GroundBridge had the tendency to induce nausea in humans. Ratchet was able to get it to stretch as far as orbit when the Autobots needed to attack the Decepticon space bridge. The GroundBridge control system was severely damaged during the Scraplet infestation, leaving Optimus Prime and Arcee marooned in the Arctic until the Autobots at base got it fixed. The Scraplets were sent through the bridge to the Arctic where they froze. Scrapheap The GroundBridge was still giving them trouble when Wheeljack arrived. This turned out to be just as well, since it was the Decepticon Makeshift posing as Wheeljack in an attempt to access the GroundBridge.

Moving the unstable D.N.G.S. by GroundBridge might have resulted in mass devastation, at least according to Optimus Prime. Using the GroundBridge on a moving target such as a train was also extremely dangerous, potentially causing mass displacement trauma, twisted limbs, or metal burn, however having the target's precise coordinates helped. Ratchet was forced to move the two older children onto a moving train to prevent MECH capturing the D.N.G.S. device. MECH terminated the Autobots' computer, forcing Prime to save the children as they could not be transported back.

Without the Autobots' knowledge, the Decepticons constructed a GroundBridge of their own. When Starscream used the Decepticon GroundBridge at the same time as the kids were using the Autobot one to return to base, the two bridges interfered with each other, resulting in the three kids being transported into a strange other dimension, along with an undead Skyquake. They were able to get enough of a cellphone signal to send a text message to the Autobots, and Ratchet replicated the original feedback loop, creating a GroundBridge portal through which they returned to reality.

When Jack was grounded, Arcee was able to use the GroundBridge to sneak into his garage so his mother wouldn't notice his motorcycle was missing.

Bumblebee snatched the Spark Extractor off Megatron while the latter was strolling through the GroundBridge tunnel back to the Nemesis.

Optimus used the Forge of Solus Prime to turn the Autobot GroundBridge into a space bridge. Regeneration After Megatron mounted an attack on the Autobot base, the Autobots abandoned base through the GroundBridge. Optimus stayed behind and used the Star Saber to destroy the GroundBridge controls to prevent the Decepticons following them. Moments later, the Nemesis opened fire, obliterating the base and the GroundBridge with it.