Passive Data Collection Overview of Passive Data Collection Technologies

  • Date: January 5, 2023

Transit operators have a multitude of reasons to collect certain types of data, ranging from the overall management and administration of the transit system, to planning needs, to regulatory reporting and funding requirements.  The ability to collect some data using “passive” data collection systems – as opposed to those “active” methods that require the collection of data either by surveyors, bus operators or other agency/operator personnel – allows for a significant amount of data to be collected, should that be desired.

Some of the data needs that passive systems are utilized to gather are described here.  They can generally be categorized into three overarching categories: Rider Data, System Data, and Maintenance/Monitoring Data.  They include the following:

Rider Data

These are elements related to riders, such as ridership.  They may include:

Passenger Counting

Passenger boardings need to be accurately counted so that transit agencies can determine the level of use of their services, both for planning reasons as well as for regulatory reporting and funding requirements.  For example, the National Transit Database (NTD) requires that transit agencies record ridership.

In addition, some passenger counting systems that record boardings and alightings can also track the level of ridership on a vehicle, thus allowing for the potential to track crowding on board a vehicle both for planning purposes as well as in real time, which has proven useful during the COVID-19 pandemic because it allows riders to gauge the level of crowding on a vehicle.

Passive data collection systems that accurately count riders are able to provide ridership reporting data for the purposes of the National Transit Database

Market Preferences

Related to ridership tracking, some data collection systems can allow the transit operator to determine the relative popularity of certain services and times of day when services are needed (thus allowing for inferences regarding trip purpose).  This data can be useful for planning purposes.

Revenue Tracking

Depending on the fare payment systems utilized (see the New Fare Systems and Payment Technology Guidebook), some transit systems can track the sources of revenue (fares paid) by route, by customer type, by payment type and by various other factors.  Similar to some of the other data collected by passive systems, this data can be useful for planning purposes, particularly in terms of fare policy.

Potential for Passenger Origin/Destination Data

Some advanced passive data collection technology allows for the collection of rider origins and destination locations, as opposed to boarding/alighting location.  These can be useful for system planning purposes, as well as some potential regulatory reporting requirements.

The New Fare Systems and Payment Technlogy Guidebook has more detailed information on fare collection technologies and their uses

System Data

These are elements related to the performance of the transit system itself. In particular, this focuses on bus route and system performance. There are several systems that can track the actual position of a bus relative to the location where it is supposed to be and can thus develop a comprehensive dataset of on-time performance and other reliability metrics.  These systems can be used both for planning purposes as well as in real time, informing riders of the arrival status of a specific bus.

Maintenance and Monitoring Data

These elements relate to the monitoring of the vehicle fleet and (depending on the technology selected) the operators.  They may include:

Driver Safety Tracking

Some systems can track the driving characteristics of a bus operator, such as acceleration rates, sudden brake applications, et cetera, so that remedial training can be assigned.

Vehicle Health Monitoring

There are systems available that can monitor certain data points on board a bus – for example, engine temperature, fluid levels, rate of fuel and/or electric power charge consumption, or specific fault indicators – and either record or transmit the data to an operator’s maintenance staff.  This allows the staff to more closely monitor a vehicle’s performance and maintenance needs and keeps an operator’s fleet in a better state of good repair.

Over the past few years, various types of technologies have been developed to help collect these various types of data in a passive manner.  This not only includes ongoing improvements to relatively older technologies like Automated Passenger Counters (APCs) and Automatic Vehicle Location (AVL) systems, but also newer technology driven by the proliferation of mobile smartphones that allow for data to more easily gathered.

All of the various passive data collection technologies can use multiple methods to transmit the data they collect – the data can be transmitted wirelessly to a “base station” server when a vehicle is in its storage facility, or it could be uploaded to a server in real time, or the data may need to be downloaded through an actual “hardwired” physical connection.

Some of the various types of passive data collection system technologies are described here.  They include:

Automated Passenger Counters (APCs) and Automatic Vehicle Location (AVL) Systems

These devices are most typically utilized in conjunction with each other.  AVL systems utilize a global positioning system (GPS) to determine vehicle location.

APCs allow for the accurate recording of boarding and alighting data, and – when used in conjunction with AVLs – allow that on-and-off data to be matched and linked to a geographic location, most typically a bus stop or transit station.  APCs must be calibrated and verified so that they can be used for National Transit Database (NTD) reporting and allow for the replacement of “active” methods such as surveying or utilizing bus operators to record ridership.  They allow for the continuous comparison of ridership data with fare collection data, and also allow for the provision of real time information regarding the level of crowding on a vehicle.  It should be noted that it is typically easier to have a system’s entire bus fleet equipped with AVLs and APCs, as that eliminates the need to “cycle” the buses equipped with APCs and AVLs through all the bus routes (and trips) and through all the differing schedule days (such as weekdays, Saturdays, Sundays, holidays, and so on) that a system operates so that a sufficient “sample” of ridership levels is developed.  By having the entire fleet equipped with AVLs and APCs, it greatly simplifies the systemwide scheduling and vehicle assignment process.

Some types of APC and AVL systems also integrate the capability to measure other elements of transit system use using sensors, such as (for example) deployment of the wheelchair ramp or use of the bicycle rack.  While these types of additional data points may not always be required for NTD reporting, they can serve a useful planning function as they can indicate (for example) where to prioritize accessibility improvements at bus stops and sidewalks that meet the Americans with Disabilities Act (ADA) or where to locate bicycle racks along the transit system.

Taken together, APC and AVL systems provide transit systems with a large amount of data (which must still be analyzed) regarding the use of the transit system and its routes on a temporal (i.e., time-based) basis, a geographic basis and a directional basis.

There are two technologies that are most typically used by APC systems:

Door Sensor-Based Passenger Counters

These electronic devices use invisible infrared beams located at the doorways of the transit vehicle.  Depending on the number of times and the order these beams are broken, the number of riders and whether they are boarding or alighting can be determined.


Video-Based Passenger Counters

These devices use cameras and associated software programs to count riders.  While usually utilized at stations or bus tops, these can also be used on board a transit vehicle.

APC systems must be regularly calibrated and validated in order to be able to be used for National Transit Database reporting

Mobile “Smartphone” Enabled Systems

There are several ways in which mobile smartphones can be used for passive data collection.  These include:

Mobile Fare Payment

Smartphones can be used to pay fares through a variety of software types; depending on the software and the settings selected by the smartphone user, a wealth of data can then be gathered including the fare paid, where it was paid, what payment method was used, and so on.

Bus Tracking/Crowding Applications

As previously mentioned, with the use of AVL and APC systems transit agencies can provide real time tracking information to riders so that they can view estimates of bus arrival times, a specific vehicle’s location, the level of crowding estimated on board, and other factors.



Aggregated Smartphone Movements Data

Several vendors aggregate data from mobile smartphones (again, depending on the software and settings selected by the smartphone user) to provide a variety of data points, such as trip origins and destinations, travel mode shares, travel movements along corridors by direction and time of day, and so on.  This data is typically anonymized so that the induvial user’s privacy is maintained.

Smart Card-Based Travel Data

Some transit agencies use “smart cards”; these are fare payment cards that can be filled at fare vending locations or linked to credit and/or debit accounts.  The data from the use of these cards provide certain types of information including the fare paid, where it was paid, what payment method was used, and so on.

Agency Website Usage

Depending on the transit system, some agency websites can be utilized to gather data regarding various subjects, such as trip planner queries and other elements that can be useful for planning purposes.

Driver Safety Tracking Systems

As previously mentioned, some software systems can track the driving characteristics of a bus operator, such as acceleration rates, sudden brake applications, et cetera, so that remedial training can be assigned.

Vehicle Health Monitoring/Performance Tracking Systems

As previously mentioned, these systems allow for the tracking of specific elements on a vehicle so as to help improve vehicle maintenance and keep the fleet in a state of good repair.  These systems may include items such as fuel/electricity use sensors, speed sensors, and so on.

The main theoretical advantage to passive data collection systems is that – as they are not “active” – the automated data collection system frees up labor hours for tasks that cannot be easily or as effectively automated, such as customer service kiosks, bus operations, and safety and security functions.  Furthermore, because they are automated, these systems can provide a more continuous stream of reporting than systems that rely on random sampling.

These methods of collecting data can be used for a variety of purposes. As was previously mentioned, APC units can (for example) provide important information on the highest ridership routes or stops for service planning and marketing departments, especially when combined with demographic information from the Census Bureau and can assist with NTD reporting once the systems have been validated for those purposes.  Data from mobile fare payment applications can support Title VI fare equity analyses by showing the different pass usage rates on various routes.

However, as will be described in other portions of the Passive Data Collection Guidebook, while the automated and passive collection of data allows for less labor to be used in gathering the data, it does not obviate the need for skilled staff to nonetheless analyze the data, particularly given the raw level of data that passive data collection systems can produce and the need to be able to “scrub” through the data to decipher certain anomalies and produce useful information.

Data may be gathered passively – nonetheless, the analysis of any data collected must be done actively by skilled staff for all the data to be truly useful