The Pennsylvania Railroad's class T1 duplex-drive 4-4-4-4 steam locomotives, introduced in 1942 (2 prototypes) and 1945-1946 (50 production), were the last steam locomotives built for the PRR and arguably its most controversial. They were ambitious, technologically sophisticated, powerful, fast and distinctively streamlined by Raymond Loewy. However, they were also prone to wheelslip both when starting and at speed, complicated to maintain and expensive to run. The PRR decided in 1948 to place diesel locomotives on all express passenger trains, leaving unanswered questions as to whether the T1's flaws were solvable, especially taking into account that the two prototypes did not have the problems inherent to the production units. An article appearing in a 2008 issue of the Pennsylvania Rail