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He called it Bio-Fusion, the technique of manipulating genetic material to splice with mechanical attachments.
~ Owen Routh on Bio-Fusion

Bio-Fusion is the process of merging organic materials with mechanical implants.


Originally starting off as an experimental attempt to revive Thomas back from the dead, Bio-Fusion was used multiple times on multiple people to fuse them with various trains as a way of tourism for Sodor. But these Bio-Fusion experiments didn't have as much work put into them as Thomas did. Therefore a lot of the bio-fused engines had various problems, with most of them either becoming too sick to work or dying during their operation or on their first test run as a result. After Thomas had found out he was never Bio-Fused, a government enquiry was launched involving the events on Sodor, with Bio-Fusion being banned the following year. However, China still uses Bio-Fusion as a compulsory punishment for political criminals. Bio-Fusion was also banned in Europe, though the trains were still required to run.

However, despite the ban, the government continued Bio-Fusion through HiT Logistics until 2015.