Determining critical rail line blocks and minimum train headways for equal and unequal block lengths and various train speed scenarios

This paper presents a primary model to maximize rail line capacity by minimizing the train headway, defining block time as the time when a train first enters until it leaves the block. The analysis was conducted under a fixed-block system, which allows only a single train to remain in the block. A critical block was identified to determine the minimum safe headway as a function of the train speed, train length, number of trains, and block length. A time–distance diagram was used to analyze operations with equal and unequal block lengths. For two trains operating at the same speed on unequal blocks, the maximum block length defined the minimum headway. For two trains operating at different speeds, a hierarchical analysis was required to identify the minimum headway. Shorter block lengths and a strategic train order affected rail line capacity. The maximum capacity was achieved when two trains operated at the same speed.