在批林批孔运动推动下,西直门电务段以“鞍钢宪法”为指针,为了提高首都道口的安全,组成了三结合实验小组,研究试验了阀式轨道电路和小型组匣式道口自动通知、自动信号,于1973年11月安装在京包线双清路道口使用。此种道口自动通知,自动信号采用阀式轨道电路,由阀式轨道电路,室内控制及表示的组匣和对公路的道口闪 In the forest approved bailong campaign, Xizhimen electricity segment to “Ansteel Constitution” as a guide, in order to improve the safety of the capital crossing, formed a combination of three experimental group, the study of the valve track circuit and small group box-type crossing automatic notification , Automatic signal, in November 1973 installed in the Beijing-Beijing line double-Qing Road crossing to use. Such automatic notification of crossing, the automatic signal using valve track circuit, by the valve track circuit, indoor control and said the group box and the road level crossing flash