On tracks that London Underground share with National Rail third-rail stock (the Bakerloo and District lines both have such sections), the centre rail is connected to the running rails, allowing both types of train to operate, at a compromise voltage of 660 V. Underground trains pass from one section to the other at speed; lineside electrical connections and resistances separate the two types of supply. These routes were originally solely electrified on the four-rail system by the LNWR before National Rail trains were rewired to their standard three-rail system to simplify rolling stock use.
কেন বাকেরলু ও ডিস্ট্রিক্ট লাইনের কিছু অংশ থ্রি-রেল সিস্টেমের আওতায় আনা হল?
to simplify rolling stock use