TRAFx Infrared Counters
The CT Trail Census employs TRAFx brand infrared (IR) pedestrian counters to track trail use. The IR counters register a temperature differential between background levels and that of a person or object passing by the IR scope and compile these “hits” into hourly totals. The counters collect data 24 hours per day for as long as they are installed. While they generally work well, the counters do have some limitations. They cannot distinguish between different types of users (e.g., pedestrians vs. cyclists), nor can they determine direction of travel. Two or more individuals passing the counter simultaneously or in rapid succession may only register as one “hit” by the counter, referred to as “occlusion error.” Fast moving cyclists might not be registered by the counter. Overcounting may occur in certain instances such as when pets or wild animals pass the counter, but typically, TRAFx IR pedestrian counters undercount trail users. To account for occlusion errors, Adjustment Factors are applied.
Uses vs. Users
The count data shows the number of uses, not individual visits or visitors. Trail users who travel out and back on the same route will pass the counter twice and two uses will be counted. For trails with primarily out-and-back traffic, trail visits can be estimated at half of the count total. The counts reflect uses at the point on a trail where the counter is installed. The figures are not indicative of use of an entire trail or trail network.
Adjustment Factors
To account for typical undercounting and to provide more accurate use figures, the raw count data are adjusted, or calibrated, using manual counts conducted by volunteers and CT Trail Census staff. The person is stationed at the counter location for a full hour and counts trail users as they pass by. The manual counts conducted at the trail counter location are then compared to the counts registered by the IR counter at that location for the same hour. Previously, annual calibration factors were developed from manual counts conducted each year and a minimal factor was applied to trail locations where manual counts were not conducted during that year.
Adjustment factors for data posted on the data dashboard for 2022 and earlier used adjustment factors developed from manual counts for all years through 2022. Correction factors for 2023 and later are updated with the addition of the current year manual counts.
Permanent IR Counters 2023
| Adjustment Factors |
||||
| Trail Name/Counter Location | Town | 2022 and prior | 2023 | 2024 |
| Air Line Trail East Hampton | East Hampton | 1.30 | 1.30 | 1.30 |
| Air Line Trail Portland | Portland | 1.20 | 1.03 | 1.02 |
| Air Line Trail Thompson | Thompson | 1.92 | 1.92 | 1.72 |
| Air Line Trail Willimantic | Willimantic | 1.69* | 1.69* | 1.71 |
| Bluff Point Trail Groton | Groton | 2.37 | 2.30 | 2.39 |
| Charter Oak Greenway Manchester | Manchester | 1.47 | 1.49 | 1.25 |
| CTFastrak Trail New Britain | New Britain | 2.65 | 2.65 | 2.65 |
| Farmington Canal Heritage Trail Cheshire | Cheshire | 1.27 | 1.31 | 1.32 |
| Farmington Canal Heritage Trail Hamden | Hamden | 1.53 | 1.52 | 1.50 |
| Farmington Canal Heritage Trail New Haven | New Haven | 1.72 | 1.73 | 1.73 |
| G&S Trolley Trail Groton | Groton | 1.06 | 1.06 | (short-term) |
| Hop River Trail Bolton | Bolton | 1.76 | 1.71 | 1.70 |
| Hop River Trail Vernon | Vernon | 1.43 | 1.39 | 1.39 |
| Larkin State Bridle Trail Oxford | Oxford | 1.03 | 0.99 | 0.98 |
| Middlebury Greenway | Middlebury | 1.50 | 1.51 | 1.55 |
| Naugatuck River Greenway Trail Derby | Derby | 1.69 | 1.63 | 1.60 |
| New London Waterfront Trail | New London | - | - | 1.49 |
| Norwalk River Valley Trail Redding | Redding | 1.00 | 1.80 | 1.80 |
| Norwalk River Valley Trail Wilton | Wilton | 1.54 | 1.45 | 1.52 |
| Riverfront Recapture Trail East Hartford | East Hartford | 1.45 | 1.45 | 1.45 |
| Riverfront Recapture Trail Hartford | Hartford | 1.27 | 1.27 | 1.27 |
| Shoreline Greenway Trail Madison | Madison | 1.66 | 1.68 | 1.77 |
| Still River Greenway Brookfield | Brookfield | 1.52 | 1.53 | 1.51 |
| Sue Grossman Trail Torrington | Torrington | 1.64 | 1.49 | 1.54 |
* due to manual counts availability, the general adjustment factor from the Air Line State Park Trail Report was applied
Short-Term IR Counters 2023 & 2024
| Adjustment Factors |
|||
| Trail Name/Counter Location | Town | short-term 2023 | short-term 2024 |
| Charter Oak Trail Manchester Middlesex Community College | Manchester | 1.33 | - |
| Cheney Rail Trail Manchester Middle Turnpike | Manchester | 1.14 | - |
| Cheney Rail Trail Manchester The Mills | Manchester | 1.38 | - |
| Farmington Canal Heritage Trail Lock 12 | Cheshire | - | 1.27 |
| G & S Trolley Trail Groton | Groton | - | 1.06 |
| Hop River Trail Andover Center St | Andover | 1.19 | - |
| Hop River Trail Manchester Colonial Rd | Manchester | 1.16 | - |
| Hop River Trail Willimantic Kiosk | Willimantic | 1.51 | - |
| Niantic Boardwalk East Lyme | East Lyme | 1.78 | - |
| Quinnipiac River Linear Trail Wallingford | Wallingford | 1.04 | - |
| River Trail New Milford North Entrance | New Milford | 0.73 | - |
| River Trail New Milford South Entrance | New Milford | 1.1 | - |
| Shoreline Greenway Branford Westpoint | Branford | 0.70 | - |
| Shoreline Greenway East Haven | East Haven | 1.33 | - |
| Talcott Mountain State Park Trail | Simsbury | - | (not calibrated) |
note: unusually low or high factors can be due to low number of counts, low usage, equipment malfunction or weather related anomalies
Missing Data
CAUTION: The completeness of datasets presented varies between locations.
Not all counters were installed or operated during the same time periods. Additionally, counter malfunction, insects, vandalism and other issues can result in periods of missing data. Common causes of missing or corrupted data are moisture in the IR scope, solar-heated vegetation within view of the IR scope, nesting insects or vegetation obstructing the IR scope, or technical malfunction. The issues are usually very apparent in the data with either zeroes, no data, or wildly high or inconsistent numbers being recorded by the counter. In these cases, the data were eliminated from the dataset. To account for missing data on annual use estimates, the annual totals were calculated by multiplying the average daily use for days with valid data on each trail by 365 (366 in leap years).
Short Term vs Long Term Counters
The Trail Census Dashboard displays data from counters installed "long term" (one year or more - many continuously since 2017!) as well as "short term" (weeks to months). Counters installed long term require regular monitoring from local volunteers, and at least four visits per year by CT Trail Census staff to download data and for regular maintenance. With so many counters spread over the entire state, getting to all counters during just one round of visits can take several days of staff time, and hundreds of miles of travel.
Upon increasing demand, the Trail Census team now deploys additional IR counters for about a month each to allow for more locations to gain access to trail use data. They could be placed at additional locations for established trail census partners, or first location(s) for new partners. Extended deployment before counter relocations or new installments without a full year of data are treated as a short-term counter.
A minimum of four weeks of recording is a reasonable duration that provides enough data for each location to gain an initial understanding of trail use, and a good representation of hourly and daily use patterns.
Note: Since counters at short term count locations were installed and uninstalled on varying days of the week, and for varying amounts of time, the summarized monthly and weekly uses shown for short-term counters might not accurately represent full week or month counts.