Barrier-free travel

Individual travel assistance systems for passengers with special mobility needs

By 2022, the German Passenger Transportation Act (Personenbeförderungsgesetz) will require barrier-free accessibility in public transport. The common goal is to achieve the accessibility of public transport services for all groups of society, especially considering the particular needs of people with special mobility needs. The research project aim4it focuses intensely on a barrier-free travel assistance system.

About aim4it

aim4it logo

Aim4it is a project funded by the EU, where INIT is working together with partners of research institutes (DLR, FH Johanneum, Bergische Universität Wuppertal, University of Poznan), public transport operators (Wiener Linien) and industry partners (mentzDV, signtime, matrixx, Fluidtime). The project focuses on a future public transport system that will be inclusive and fair to all groups of society, especially for passengers with special mobility needs.

For a given destination, barrier-free mobility chains should be set up. Every mobility chain is accompanied by a “barrier-free” information chain.

Passengers with special mobility needs want to get all relevant information about departure times and necessary transfer procedures. This information must be kept up-to-date and understandable before, along the way, as well as after the journey. Significant information should be conveyed optically, acoustically and/or tactilely. More specifically, new travel assistance approaches for passengers with special needs, a barrier-free travel experience, as well as a feedback mechanism aimed at the continuous improvement of public transportation accessibility, will be developed.

Smartphone app for passengers with special mobility needs

With a smartphone app, the passenger with special mobility needs gets assistance in trip planning. At the beginning of his planning, he enters the start point, the destination, and his special mobility requirements into the smartphone (e.g. need for driver assistance). The smartphone app sends a request for a barrier-free trip to the Intermodal Transport Information System (ITIS). Based on the end points of the requested trip, the ITIS performs barrier-free routing.

The route reflects information from augmented digital maps (e.g. based on crowdsourcing projects such as “wheelmap”), error messages from the Intermodal Traffic Control System (ITCS), as well as error messages entered by local service staff at stations (e.g. defect of an escalator). The routing algorithm takes the mobility requirements into account and, if necessary, creates a user-specific request for connection protection (with maybe prolonged waiting times). This request is sent from the ITIS to the ITCS where the decision whether or not this request is accepted or denied is made either automatically or by the dispatcher.

The ITIS receives this decision as a response and, if the connection protection is declined, can initiate a re-routing. The barrier-free route, compiled by the ITIS as a final result, is sent to the smartphone app. There it is displayed and serves as input for barrier-free navigation along the trip chain.

Support before and during the trip

An additional feature of the app is the request for bus driver support to board the vehicle. This attribute is entered as part of the barrier-free trip request and is sent to the ITIS. From the ITIS, this request is relayed to the ITCS, where the corresponding vehicle is identified. Via the existing data link between the ITCS and the vehicle, the request for driver assistance is sent to the bus. The driver is informed via his display as a locationbased service when the vehicle approaches the respective station.

With the app, the passenger gets on-trip assistance. Whenever service irregularities (e.g. delays, cancellations, missed connections) are detected in the ITCS, this error information is forwarded to the passenger by the ITIS. For special needs passengers, this information is automatically transformed into a video stream displaying this error information in sign language. This information is made available for deaf and hearing impaired passengers on their smartphones.

In addition to just following a static pre-planned route, dynamic re-routing is an integral part of the system. Using information available in the ITIS, each barrier-free route will be monitored. Whenever a deviation is detected, re-routing will be automatically triggered and the passenger informed about alternatives. Last but not least, during the trip, the passenger can issue a stop request along with a request for driver assistance at any time. This information is sent to the vehicle with an IP-based communication link so that it can be displayed on the driver’s interface.


The main results for INIT will be the defined interfaces between the ITIS and ITCS for the requests of connection protection and driver assistance. These interfaces can also be used for pickup and drop-off requests in demand responsive transportation systems. The interfaces between smartphones and the vehicles for direct communication will be defined as well. All interfaces are based on the German VDV431 standard (TRIAS) and will be available for our customers at the conclusion of the project.


Gunnar Rehbein

Manager Technology
init SE