Effect of Guaranteed Emergency Braking Rate and Gradient on Turnback Headway Time in Metro Lines

Modern metro lines deploy Communication-Based Train Control (CBTC), which uses moving block that allows shorter headway times. Maximum operation speed, traction package's delays and reaction times, guaranteed emergency brake rate (GEBR), track gradients, and switch locations affect the headway time. This paper focuses on the GEBR (from 0.6 to 1.1 m/s
²
) and track gradient values' (±4.0% with 0.5 steps) effect on the headway time. One hundred two combinations of both parameters are used in simulations carried out with Hi-SimuX Rail Simulation Suite, which can calculate safe braking distance as per IEEE standards. The paper quantifies the effects of the GEBR and the gradient values on the achieved headway time on a metro line that shows that GEBR, gradient, GEBR&Gradient might affect the headway respectively up to 43.83%, 43.17%, 51.5%. Also, a formula was produced defining the relationship between headway time, the GEBR, and gradient values.