in the early 950s Portbell was undergoing a large growth of the suburbs and MNR was looking to expand its commuter electric service to the quickly growing suburbia so construction of a new bridge to the peninsula was constructed it carried 4 highway lanes and two rail tracks electrified at 3kV DC and to serve this line Mushroom National built 60 M7 power cars and 170 trailing cars they used mostly stainless steel construction, with restitive traction control
