To determine the stability of the metrobus in unstable driving modes

Abstract

Recently in many cities of the world began to introduce so-called «metrobus» or BRT (Bus Rapid Transit) systems, which became a cheaper alternative to the metro and other rail transport, in particular trams. The aim of the work is to determine the stability indicators of the metrobus in the transitional traffic modes, in particular when performing such manoeuvres as «steering wheel jerk» and «shuffle». For this purpose, the equations of metrobus plane-parallel motion are supplemented by equations of the links of the road train in the vertical plane by halopilation (tangage, trim) and roll.The critical straight-line speed of the three-link metrobus has been determined, which was 32,06 m/s, and this speed is independent of the corners of the steering wheels of the bus and the trailer links.It has been shown that as the steering wheel angle of the bus increases, the difference in the folding angles of the bus increases, with the second folding angle significantly exceeding the first, especially considering the roll of the metrobus body. It has been established that the greatest rolls and loads of the metrobus axles are those of the last trailer, which is the limiting factor for the critical speed. The lateral accelerations of individual metrobus links and their yaw velocity when performing the manoeuvre «steering wheel jerk» and «shuffle, Sl = 24 m», show that both the bus and the second trailer link are a limiting factor when performing various manoeuvres, but the acceleration value does not exceed the permissible 0,4g, so its stability under these conditions is ensured.