around the same time, tra began ordering the first of several series of dmus, starting with the dr2800 series from tokyu car, a derivative of the american budd company's proven rail diesel car design, introducing the new service to non-electrified lines. these were followed up with the dr2900 series, built with a modified exterior but to the same essential by nippon sharyo. a subsequent order incorporated enough differences to warrant a separate designation, and these were labelled the dr3000 class despite being of the same design. the final series of dmus for this service would be the dr3100 series, ordered in the early 2000s as a way to minimize development costs for the concurrent dr1000 series of commuter dmus, with which they shared many characteristics, both in appearance and machinery. with the entire length of tra's main lines electrified, there have been no subsequent orders for dmus.