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- 7 - Method of Operation

This accident happened on ICG Chicago Division track which had been electrified to accommodate suburban trains. Train operations were controlled by automatic—block signals, timetable, and special instructions. Train orders were not used in suburban service. Special instructions were generally issued as bulletin orders (for matters directly involving train operations) or bulletin notices (for matters involving other transportation matters).

The automatic-block signal system, which was installed from 1926 through 1929, consisted of signal lights which displayed red, yellow, and green aspects. The signals were suspended from overhead structures that spanned the tracks and were installed on tracks 3 and 4 to accommodate northbound traffic only. The red aspect of Signal 3-3.10 (at 27th Street) and Signal 3-3.60 (at 31st Street) indicated restricted proceed and did not indicate stop.

Suburban train movements were directed by the ICG load supervisor. Use of the tracks through the accident site was controlled by the operator at 67th Street Interlocking. Because train 416 stopped at most stations, it was always routed on track 3. The routing of train 720 depended on conflicts with other trains. Normally, 720 was routed on track 3, although it was not scheduled to stop between 67th Street and Roosevelt Road.

The maximum authorized speed for trains using tracks 3 and 4 through the accident site was 65 m.p.h. A 25-m.p.h. authorized speed applied to train operation north of 23d Street.

On weekday mornings between 7:30 and 8, 18 trains passed through the 27th Street station on tracks 3 and 4. Six of these trains were scheduled to pass 27th Street between 7:30 and 7:38. (The schedules for trains 416, 720, and 718 are contained in Appendix A.)

Train 416 was the only train that stopped at the 27th Street station between 7:30 and 8 a.m. Although the stop was listed in the timetable as a flag stop at 7:31, 416 actually stopped every morning to discharge workers of the nearby Michael Reese Hospital.