During the period of the Russian Revolution OTL the Czech Foreign Legion in Russia effectively took control of the Trans-Siberian Railway, while using it to get to a safe port so they could return to their homeland, now the new state of Czechoslovakia. When they transferred to ships the situation vis a vis the TSR reverted to normal.
However, in this timeline they decide to remain on the TSR and run it autonomously. They recruit others to their cause, and provide a neutral military presence when required in the localities near train stations, and maintain order among the passengers. They are thus regarded in a neutral or positive light.
When Lenin and Trotsky attempt to retake the TSR, the CFL manage to hold their own.and state that the logic of 'All power to the Soviets' and the Communists' statements that they are acting in the name of the working classes means that the CFL have every right to their present position - and in due course the situation is accepted. In later times exchanges of spies utilise the TSR (rather than OTL Checkpoint Charlie).