Tracking Stair Usage

If you are thinking about implementing a stairwell intervention in your building, you may want to consider tracking the use of the stairs before, during, and after the renovation phases are complete. Direct observation, video cameras, and infrared sensors have all been used to track stair usage in past interventions and new technologies are being developed. Each method of tracking stair use has its own benefits and limitations. The method you choose may depend on the cost, practicality, and accuracy involved.

What We Did

Infrared Sensors
For the CDC "StairWELL to Better Health" intervention, infrared beam sensors were installed to collect baseline data and conduct ongoing data collection of stair traffic. These proximity sensors were placed at each of the floors' stairwell entries and recorded one passage when a person moved between a transmitter and receiver. Therefore, each trip in a stairwell involved two passages, one to enter the stairwell and one to exit. Information from the sensor is downloaded onto a computer and reports can be generated. Whereas direct observation may be able to measure whether an individual is going up or coming down a stairwell, infrared sensors only allow you to track passage through an entrance or exit. In addition, infrared beams are not able to recognize and separate individuals from groups of people who may pass through the beam at the same time. Therefore, passage counts could be underestimated in busy stairwells.

What You Can Do

Not everyone has the budget (or the need) for Infrared Sensors. We chose them because we wanted a clear idea how various phases of the project affected stairwell use. Below are two more possibilities for tracking stairwell use if you are interested in seeing how your improvements change use in your building.

Direct Observation
Direct observation is the "low –tech" method to measure stair use. It simply requires one or more people to watch and record entrance and/or exit from the stairs. Typically, observers are discreetly located at a decision point at the foot of the stairs and/or elevators. Observers count the number of people entering and leaving the stairwell or elevator and may record demographic information as well as direction of use (entering or exiting). Direct observation, however, is usually only done over short time periods (one day to one week) and in short time frames (2–5 hours). It is not a method that can get continuous tracking information over a long period of time, however it is a low-cost method that could give you an idea of the stairwell's use.

Video Cameras
Similar to direct observation, video cameras also can be used to watch and count stair traffic. A video camera or multiple cameras are placed at points of decision for stair and/or elevator use. Recorded data can then be reviewed at a later point in time. However, this may be a time-intensive task because it requires watching the hours of recordings in entirety. Privacy concerns are the biggest limitation of using video cameras to track stair usage.

In the Future: Promising Technologies

CDC researchers are exploring innovative technologies for physical activity assessment in a variety of settings.

• "SmartMat": Through a CDC Small Business Innovative Research contract, a technology development company is building and testing the "SmartMat" system for measuring physical activity within controlled areas. Prototypes of the "SmartMat" resemble a plain, industrial carpet that can be placed on the ground in various locations such as a stairwell, an outdoor sidewalk, and an outdoor trail. The mat will accurately count people and other objects (e.g., bicycles) crossing the controlled area and will allow for easy data access through direct computer download, Smartcards, or Palm PCs. Testing is currently underway to determine the feasibility of use in everyday situations.
• Automated Image Monitoring System: Researchers at the University of South Carolina Prevention Research Center have received funding from the Robert Wood Johnson Foundation to develop, field test, and refine a new, automated monitoring system that relies on camera images for tracking physical activity in varying locations including indoor stairwells, paved tracks, and natural surface trails. The sensor will include special features that allow counts of multiple modes of transportation (e.g., pedestrians, cyclists, etc.), compensate for changes in environmental conditions, and capture individuals moving in a group. The system is designed to avoid privacy concerns by tracking an individual but does not identify them.

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