 Serial production of the T1000 started in 1964 by Strømmens Værksted , NEBB and AEG . Until 1978 , 162 cars were delivered to Oslo Sporveier . These were manufactured in four series , designated T1 through T4 , with minor changes to specifications . During the late 1970s , the western suburban lines which were part of the tramway needed new rolling stock . Oslo Sporveier was at the time considering connecting the metro with these lines , and between 1978 and 1981 , 33 new T1300 cars were built . The only difference from the T1000 was that they had a pantograph that allowed them to operate on the tramways . They also retained the necessary technical appliances to run on the metro . The new T1300 were designated T5 and T6 . From 1985 to 1989 , 16 T4s were rebuilt to T1300 and designated T7 and T8 . 
