Board Thread:Questions and Answers/@comment-27839092-20160221063709/@comment-24.130.239.182-20160221111900

Wilma and Johann only have steam engines. Bobby originally accepts only Steam and Diesel, but you can send him electric trains after his contract #13. Similarly, rest of the contractors have restrictions on what trains they accept, while some of them allow you to let them send a higher technology train after a certain contract. Take a look at all the contractors to see about individual contractors and their contracts.