A Risk Assessment Model and Safe Stopping Strategies for Fire Train Fixed-Point Stopping in Railway Tunnels

Abstract

When a train catches fire inside an extra-long tunnel, fixed-point rescue is widely used. The distance between fixed points determines whether the train can stop safely. However, in many countries, regulations dictate a maximum of 20 km, and each tunnel and train have different characteristics. Fixed points are mainly designed based on experience, which may be detrimental to precise risk control. In this paper, a risk probability calculation model for fire train fixed-point stopping in railway tunnels is developed, which takes into account train operation characteristics and tunnel engineering parameters. Based on quantitative calculations, the role of major factors is discussed, and an empirical formula for safe deceleration at different station distances is established. The study reveals that: 1) the reliability of the 20-km distance standard is contingent on train equilibrium speeds exceeding 80 km/h; 2) at a distance of 20 km, the risk probability of fixed-point stopping varies from 0.011% to 10.06%. Better train braking capacity and greater uphill slopes can reduce the risk, with the latter playing a more significant role; and 3) there is a safe deceleration that maintains the risk probability below 0.03%. This is determined primarily by longitudinal grades and train braking capacity. As the fixed-point distance increases, the required safe deceleration grows exponentially.