June 25, 2015 6:23 AM EDT

1 The bot extrudes cords of molten steel in a pattern and waits for them to cool before moving ahead–like a train making its own tracks

2 Along the way, software continuously monitors for engineering errors and instructs the bot to correct course if necessary

3 When the 24-ft. (7 m) bridge is done (it’s expected to take two months), it will support foot traffic and feature intricate designs

This appears in the July 06, 2015 issue of TIME.

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