First published in the trade magazine: "Der Stadtverkehr" Issue 07/08 2021

Structured light for new public transport services

  • The mammoth task currently facing municipalities is to achieve the climate targets. Public transportation is an important ally in this effort. But how can more people be persuaded to switch to buses and trains? And what makes it easier to get back on the bus after the pandemic? In recent months, an established solution has taken on a new meaning: automatic passenger counting (APC) is becoming the information basis for displaying and forecasting utilization in real time.

Passengers today find load information very important and valuable. Transit agencies are now realizing that there are many more opportunities in APC data to offer new services and become more attractive to customers. But how does passenger counting actually work? Which technologies have proven themselves? What new developments are there?

While manual passenger counting involves personnel riding in the vehicle and counting the number of passengers boarding and alighting, automatic passenger counting involves sensors, usually in the vehicle doors, determining this data. The advantages of an APC system are obvious: technology-based counting is less prone to error. It achieves an accuracy of up to 99%. If all vehicles are fully equipped with counting sensors, the exact number of passengers can be determined instead of using extrapolations and statistical measurement runs. This offers further advantages, such as utilization information in real time. After an initial investment, there are hardly any costs for the ongoing operation of the systems.

Mobility data in public transport

Interface to smart mobility

Mobility data is the new gold, they say. But how valuable is APC data for transportation companies? In German-speaking countries, the count data usually serves as the basis for revenue sharing between the transport companies of a transport association. In most cases, the latter provides a network and resources to transport people. The collected ticket money and the subsidy from the municipality are then distributed to the members in the transport association based on certain parameters, such as passenger numbers and passenger kilometers performed. APC data is time-stamped and combined with other data such as timetable and stops on a line by analysis software. This forms the basis for timetable, network and operations planning as well as quality control of a transport company. The aim is to control the utilization of vehicles and transport networks, to optimize door opening times or to plan stops better and to record revenue reports and key figures.

APC data for better public transport

Not only documentation of usage, but also real-time monitoring and forecasting

In Scandinavian countries in particular, APC Using APC data for new services In German-speaking countries, too, local data from APC systems is increasingly becoming a source of knowledge for mobility providers, enabling them to tailor their services to passengers' needs.

Combined with other data such as GPS and WiFi, data from APC systems in public transport vehicles reliably map very accurate, local movement and distribution information. This makes it possible to actively shape the occupancy of vehicles, whether in the sense of social distancing in times of pandemic or capacity planning for special mobility needs such as passengers in wheelchairs or carrying a bicycle.

Automatic passenger counting (APC)

Technologies at a glance

The best-known and most widely used devices for counting passengers include infrared and time-of-flight sensors as well as stereoscopic cameras, which are usually installed above the vehicle doors and perform their services there fully automatically. Infrared sensors have the advantage that they work independently of changing light conditions and are relatively inexpensive to install. Time-of-flight sensors work on the basis of the pulse time-of-flight measurement of light. They emit a pulse of light and measure the time it takes for the light to reach an object and return to the sensor. Stereoscopic cameras use two camera images that depict the same scene. From these images, depth information is calculated that is similar to human spatial vision. So here the camera perspective is used as a tool.

The latest generation of APC sensors uses structured light technology. Here, a laser projector module generates a dot pattern that changes depending on the distance of a human or an object from the optical module of the sensor. The distortions of the dot pattern are used to create a depth image, which is then used to create the 3D profile of a person or object. These 3D profiles do not have to be anonymized afterwards, as is the case with other technologies, but they are already determined anonymously. DILAX is a specialist for APC system solutions in local and regional public transport and this year launched the DILAX SLS-1000, a structured light sensor, and applied for a patent.

Structured light

New quality and precision of passenger counting

The new sensor counts the number of people entering and exiting a vehicle. It distinguishes between adults and children and also counts objects such as bicycles and wheelchairs. Counting and object detection work reliably even in the dark or in a blur. The object data includes not only the pure number of objects, but also their height and direction of movement. The sensor trains the recognition of the objects on the basis of artificial intelligence. In addition to bicycles and wheelchairs, other object classes such as baby carriages and suitcases will soon be added.

Based on the data obtained with Structured Light technology and business intelligence software such as DILAX Citisense, public transport operators, transport associations and municipal public transport planners will be able to develop new services for passengers in the future. For example, it is conceivable to specifically display available wheelchair spaces in the current or following vehicle. In this way, the distribution of people and objects on the platform can be controlled so that all passengers can board and disembark comfortably and passenger changing times can be shortened. In addition, data from APC systems can also interact with other systems and generate high added value for customers. In interaction with sensor technology in urban areas, it is quite conceivable that other mobility services can also be controlled and booked, such as autonomous vehicles, e-scooters or bicycles. This offers customers considerably more convenience.

Author: Tom Tipolt, Head of System Solutions & Consulting, DILAX

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