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- 15 - Other Information

One witness who was seated along the left side of the first car of the Lake-Dan Ryan train stated that she saw the entire rear car of the Ravenswood train while the Lake-Dan Ryan train was standing in the Randolph Street Station and as it moved out of the station.

ANALYSIS

Safety Board investigations of a number of collisions on intercity railroads have indicated that a primary problem of human failure develops where stop and proceed signals are used and a train is allowed to enter an occupied signal block. A passenger train should not be allowed to move into an occupied signal block except under the most stringent controls, and then only in cases of an operational emergency. The ATC should preclude a motorman's inadvertent or arbitrary movement of a train into an occupied signal block. Even though the CTA is operating virtually on an absolute block system, the operating rules still permit the motorman to move a train into an occupied block.

The rules require that the motorman obtain permission from central control before he can move his train into an occupied block. The motorman's compliance with this rule does not insure against an accident because in most instances the motorman is the only crewmember onboard the train who knows what is happening. To enhance safety and to provide more positive assurance that a motorman will not arbitrarily operate past a stop signal, an electronic or mechanically operated system should be provided that requires a conscious effort before the train can be moved past the signal or into an occupied block.

Signal indications that are similar or that could result in ambiguous interpretation should not be used. The use of a red and yellow cab signal light in conjunction with the yellow speedometer arc light to present aspects with different indications could be confusing. A motorman can only determine which indication will govern his movement by correlating the cab signal indication with the speedometer are light. It is possible that a motorman under stress might misinterpret these indications. Elimination of confusing signal aspects is essential in a rapid transit or commuter line operation because of the close headway of traffic. This same situation exists where motormen are allowed to proceed on a flashing red cab signal by authority of posted instructions which do not require permission of central control. Even though there are facilities at those points that temporarily require this operation, it requires two operational techniques for the same signal indication over different lines.

The motorman of the Lake-Dan Ryan train noticed the lighted rear marker lights on the Ravenswood train. In recognition of the train's presence, he maintained a station-to-station interval between the trains.