About Arlington's Automatic Counters

Photo: Counter and Cyclist on Four Mile Run Trail Arlington County maintains a system of continuous automatic counters to detect and record bicycle and pedestrian volumes 24 hours a day at selected locations. Collecting better active transportation data is essential to building long-term support for walking and cycling, and for improving conditions for those who choose to walk and ride bikes. The County currently has 32 permanent installations, and six portable counters to gauge and monitor usage and demand.

The Bicycle & Pedestrian Counter Dashboard on BikeArlington.com was developed to display data from the counters, and to allow the public to consult, download, improve, and analyze it. The dashboard shows the total number of bicyclists and/or pedestrians counted at each location during the time period chosen by the dashboard user. It allows for using a number of “filtering” parameters, such as mode (bicycle and/or pedestrian), direction, and day(s) of the week. The count data from each device can be graphed within the Dashboard application, or exported to an Excel spreadsheet. The Dashboard is a work in progress, and we welcome the public’s help in improving it. The counters generate “planning level” data. That means that results are correct to much better than “order of magnitude” level, and that they are the best available. No claim is made that the data is “accurate”, “precise”, or “true”. (For a brief introduction to these concepts see Wikipedia.)

Factors That Can Affect Count Accuracy

Reliable active transportation data is still a recent innovation, and Arlington is a trend-setter in the field. We recognize that the count results are subject to a number of factors that can affect accuracy, and that some user queries might return “No Data.” The reasons for this include, but are not limited to: the particular technologies employed; the age and generation of the devices themselves; and extrinsic factors such as damage, interference by insects (!), extreme weather, and vandalism. We work diligently to limit sources of machine downtime, and systematic and random error.

Limitation Due to Type of Device

Arlington's automatic counters come in several varieties. Most of the devices installed on shared-use trails distinguish between bicycles and pedestrians, generate discrete totals for the two modes, and detect direction of travel. Other counters, such as those in on-street bike lanes, only count bicycles, and assume a single direction of travel. If your query asks for direction of travel, but the counter does not have that capability, the search will return "No Data." Similarly, if your query asks for only bicyclists or pedestrians, and the counter you select does not distinguish between the modes, the search will return "No Data." Almost all of our counting instruments come from the firm Eco-Counter.

Machine Installation Dates

Arlington's automatic counters have been installed over more than five years. If the time period of your query includes dates before a particular counter was installed, any results will not include bicycle or pedestrian activity prior to installation.

Machine Downtime

Counters occasionally go offline for a variety of reasons, including routine maintenance, insect infestation, or damage. If a counter was offline for any reason during the selected time period, the results of your query cannot include bicyclists and pedestrians who passed the counter location during the downtime. Over time, we hope to develop normalized data “patches” to fill such gaps, and will flag them.

Installed Counters, Installation Dates, Models

Trail Counters

  • Custis Rosslyn, October 2009, EcoMulti, bicycles and pedestrians, no direction detection

  • * Four Mile Run, March 2011, PyroBox, bicycles and pedestrians counted without distinction

  • * Four Mile Run, April 2011, MetroCount MC 5720 piezo, bicycles only

  • W&OD East Falls Church, December 2010, EcoCombo, bicycles and pedestrians, with direction detection

  • W&OD Bon Air Park, December 2010, EcoCombo, bicycles and pedestrians, with direction detection

  • Custis Bon Air Park, December 2010, EcoCombo, bicycles and pedestrians, with direction detection

  • Key Bridge West, August 2011, EcoCombo (urban post), bicycles and pedestrians, with direction detection

  • Key Bridge East, August 2011, EcoCombo (urban post), bicycles and pedestrians, with direction detection

  • Mt Vernon Trail Airport South, September 2011, EcoCombo, bicycles and pedestrians, with direction detection

  • Crystal City Connector, September 2011, EcoCombo, bicycles and pedestrians, with direction detection

  • Theodore Roosevelt Island Bridge (at concrete bridge to Rosslyn), September 2011, EcoCombo, bicycles and pedestrians, with direction detection

  • W&OD Columbia Pike, October 2011, EcoCombo, bicycles and pedestrians, with direction detection

  • Bluemont Connector, December 2012, EcoCombo, bicycles and pedestrians, with direction detection, four pavement loops

  • Ballston Connector, December 2012, EcoCombo, bicycles and pedestrians, with direction detection, four pavement loops

  • W&OD Bon Air West, December 2012, EcoCombo, bicycles and pedestrians, with direction detection, four pavement loops

  • South Joyce Street, Southbound, December 2012, EcoCombo (urban post), bicycles and pedestrians, with direction detection, four pavement loops

  • South Joyce Street, Northbound, December 2012, EcoCombo (urban post), bicycles and pedestrians, with direction detection, four pavement loops

  • 14th Street Bridge, November 2014, EcoCombo, bicycles and pedestrians, with direction detection, four pavement loops

  • Roosevelt Bridge, December 2014, EcoCombo, bicycles and pedestrians, with direction detection, four pavement loops

*Note: The "piezo" device counts only bicycles. Pedestrian values can be approximated by subtracting the "piezo" count from the "pyro" count, which includes both bicycles and pedestrians.

On-Street Bike Lanes

  • Wilson Blvd. in the 2500 block, near Earl's Sandwich Shop, between N Cleveland and N Danville (Westbound)
  • Clarendon Blvd. at N Danville near the Starbucks (Eastbound)
  • Military Rd. in the 2500 block, near 25th Place N (Northbound)
  • Military Rd. in the 2500 block, near 25th Place N (Southbound)
  • N Quincy St. in the 1100 block, just S of Washington Blvd. (Northbound)
  • N Quincy St. in the 1100 block, just N of 11th Street N (Southbound)
  • Fairfax Dr. in the 3600 block. Currently out of service due to construction activity. (Westbound)
  • Fairfax Dr. in the 3700 block, near St. George's Episcopal Church (Eastbound)
  • Crystal Dr., in the 1800 block, just S of 18th Street S (Northbound)
  • Crystal Dr., in the 2200 block, just N of 23rd Street S (Southbound)

Additional Counters

  • Six mobile "Pyrobox" counters used for short- and medium-term counts. These do not distinguish between bicyclists and pedestrians.
  • Arlington’s #bikeometer, the first Eco-Totem on the east coast, launched April 1, 2014. Westbound Lee Highway near N Lynn Street, Rosslyn. Bicycle-only detection and display in real time. Shows cumulative daily, monthly, and year-to-date values. With direction detection, four pavement loops

Data for Developers

Data from Arlington's automatic bike-pedestrian counters is available for application developers.

Arlington County Commuter Services (ACCS) is funded in part by grants from the U.S. Department of Transportation (DOT), the Virginia Department of Transportation (VDOT) and the Virginia Department of Rail and Public Transportation (DRPT).

Counter Dashboard Links

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