To the Commission: On October 13, 1939, there v; a s a side collision between a freight trgin and a Passenger train on the Pennsylvania Rail road at Philadelphia, Pa.., which, resulted in the injury of five dining-car employees. Location and Method of Operation This accident occurred within the limits of Zoo interlock ing, at the junction of that part of the Philadelphia Terminal Division, hereinafter referred to a s the main line, which ex tends between Paoli and Holmesourg Junction, Pa.., a

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... stance of 28.2 miles, and the West Philadelphia Elevated Branch, herein after referred to a.s the branch, which extends between Brill and Zoo, a distance of 4.5 miles. Both are double-1IT.ck lines and are equipped with overhead catenary systems. Trains on the main line are operated by timetable, train orders and an auto matic block and cab-signal system, while those on the branch are operated by timetable, train orders and an auto. iatic block system. The accident occurred at the fouling point of the junction switch, which is at a point approximately 200 feet east of Zoo interlocking tower. Approaching this point from the west on the main line, there are, successively, a tangent more than 2 miles long, a 6° curve to the left 1,470 feet in length, and a tangent extending 30 feet to the point of accident and 385 feet beyond; the grade for east-bound trains is descending 0.9 per cent a distance of more than 2 miles, 1.5 percent descending for 825 feet, and 1.76 percent ascending for 375 feet to the point of accident. Approaching on the branch line, there is a tangent 2,100 feet in length, which is followed by a compound curve to the right consisting m succession of 550 feet of 6°30' curvature 400 feet of 4° curvature, and 365 feet of 8°30 l curvature, which extends to the point of accident and 45 feet beyond; the grade for west-bound trains is successively 0.7 perccne ascending for 900 feet, 0.4 percent of 500 feet, and 0.2 percent descending 891 feet to the point of accident. The interlocking machine at Zoo is of the electro-pneumatic "type and consists of 142 working levers; it is equipped with approach or time locking on all routes and advance locking for all switches. Time releases are of the clockwork type. All movements through the plant are controlled by signal indications. A model board, which indicates track occupancy, direction of traffic, and position of signals, is provided.