System management defended the move claiming cost savings from using diesel-powered buses, the high cost of electrifying new routes and the lack of any new trolley coaches on the market. Under fire from the public, the commission ordered an independent study. That study contradicted the claims of management, concluding that trolleybuses perform better than diesel powered buses on Seattle's hills and that operating costs were comparable (except for overhead wire maintenance).

By 1970, the Seattle Transit System was facing mounting financial