Wachtwagens 513 & 507
Up to 4 'Extra' trams were kept to wait to be called up for additional services in the event of delays of services terminating at Amsterdam central station. The triple axle trams in the photo had only recently acquired the large destination boxes. A month later this serie of trams were renumbered from 491-550 to 891-950. Also note the lonely Mercedes taxi at the rank.
© Henk Graalman