network. Design The stock was a compromise between the needs of longer-distance "outer suburban" passengers on the outer reaches of the line and short-distance "urban" passengers over the heavily used Circle and Hammersmith & City lines. For this reason, the trailer cars have three sets of doors per car. A distinctive feature was the use of transverse seating only, uncommon on the Underground. This is because it was designed for journeys which might last over an hour. Most of the seating was of the high-capacity transverse 3 + 2 arrangement. Four tip-up seats were provided at the rear of the driving motor. Despite each 8-car train seating 448 passengers, the stock provided fewer seats than the locomotive-hauled and T stock trains that they replaced, but more seats than the S Stock which started to replace them on 31 July 2010. The stock had luggage racks and umbrella hooks, the only Underground stock to have these features, despite their presence on most contemporary British Rail stock. The A stock were the last subsurface trains built with headlights positioned on the left side of the cab giving them an asymmetrical appearance. They also had three tail lights positioned underneath the cab, although one was removed during refurbishment. A60 and A62 stocks were nearly identical in appearance. The most significant differences were the border around the destination window on A62 motor cars and the make of compressor under the trailer cars: A60 stock used the Westinghouse DHC 5A, A62 cars the Reavell TBC 38Z. At , they were the Underground's widest trains. The stock was refurbished between 1994 and 1997 by Adtranz (now Bombardier) in Derby. Car end windows were installed, the seating was reupholstered, and the livery was updated. At the time of refurbishment, the Metropolitan line had a low priority for receiving new trains. Operation Each unit consisted of four cars: two powered driving motors at each end and two non-powered trailers in between. Each unit was further divided into two semi-permanently-coupled sets, a driving motor and trailer. In service, trains consisted of one or two four-car units coupled together. To avoid hauling under-utilised carriages, eight-car trains were divided into their component four-car units at the end of the peak hours, with one unit often stabled. At the start of the peak hours, this unit would be coupled to another single unit to create a longer train. Although this practice was