Optimisation of the Running Speed of Escalators on the London Underground

Speed reduction of escalators is commonly employed worldwide and has been shown to achieve savings in energy consumption and component wear. However, although London Underground has considered speed reduction, there is not currently a strategy in place to optimise running speed based on quantitative data. This study researches current practices, relevant previous work and state-of-the-art technology to determine the scope for investigation. Energy consumption, component wear, human factors, safety and passenger journey time are all considered. A combination of primary empirical data, theoretical calculations and secondary sources are used to derive models for a chosen escalator. These are then applied to assess possible options and recommend a strategy for London Underground. It has been found that the negative impact on passenger journey time due to a pre-programmed speed reduction during off-peak hours significantly outweighs the savings, even at low passenger flow rates. Automatic stop-start is not considered feasible for a number of reasons including excessive brake operation and the need to overcome static friction. The recommended strategy is to reduce the speed to a crawl when the escalator is unloaded, accelerating to full speed when passengers are present. This reduces the energy consumption and component wear whilst minimising the negative effect on passenger journey time, and, if used in conjunction with regenerative braking, would minimise energy lost during deceleration. Methods for early detection of passenger arrival are suggested to avoid delays during the acceleration phase. An application has been developed using MATLAB that can quantify and compare the impact of different variable speed strategies and visualise predicted cost savings.