Accessible Boarding in Chicago

Liebherr-Transportation Systems has successfully completed the commissioning of new hydraulic level control systems for the new 7000 series light rail vehicles of the Chicago Transit Authority (CTA) in Chicago, built and supplied by CRRC. The levelling system was commissioned at the CRRC Qingdao site in September 2019 on a near-series prototype. Liebherr-Transportation’s development team thus made a significant contribution to the successful and on-time delivery of the vehicles to CRRC’s customer.

The first level control systems for ten carriages have already been delivered to CRRC for final assembly. The vehicles must prove their flawless function and reliability in a one-year test phase in Chicago before series delivery starts at the end of 2020.

The level control system enables accessible boarding and alighting on the new light rail system in Chicago and makes travelling easier for people with disabilities, in particular. In addition, it is also convenient when travelling with heavy luggage. The system is able to adapt the level of the vehicle floor to exactly that of the respective platform. This is no easy task for the system, considering that a full vehicle can carry a total weight of up to 36 tons on the tracks. In addition, platform heights differ from station to station. The vehicle load can also have a spreading width of up to ten tons. This loading condition has the effect of compressing the vehicle springs – designed as steel compression springs – more or less, i.e. the carriage is higher or lower. In order to precisely adjust the floor height to that of the platform, it is important not only to know the height position of the vehicle, but also to determine the different heights of the respective platforms. Position sensors are installed on the vehicle for this purpose. When the carriage arrives at the station, the sensors detect the platform height. Based on this height measurement, four hydraulic actuators are activated per carriage which, with six tons each, pull the steel springs together between the carriage body and chassis to lower the vehicle until the exit edge exactly matches the height of the platform.