the c830c runs without a driver, using communications-based train control (cbtc), which does not require "fixed-block track circuits" to find where the train is on the track. instead, they use "continuous two-way digital communication" between each controlled train and a control center, which may control an area of a railroad line, a complete line, or a group of lines. it has been found that cbtc systems reduce costs for running the system and allow the system to be controlled more easily.