Uses vs. Users
One of the most important points to note about the count data is that it shows number of uses or trips, not numbers of users or numbers of total visitors. Trail users will be counted every time they pass the counter, meaning that a trail user who takes an “out and back” route will be counted twice. All of the trail sections counted likely have a high percentage of these types of users, but it is difficult to calculate the percentage to be used in corrections. The published data from the Census therefore represents the number of trail trips or uses not trail users.
Adjustment Factors
There are some limitations to passive infrared counter technology. First, the counters are not capable of determining the type of use so pedestrians, bicyclists, and any other user are indistinguishable in the count data. Second, there are multiple conditions that can result in error in the data including undercounting due factors such as multiple people passing the heat sensor at the same time, traveling side by side, bikes passing the counter too fast, mechanical error, or technical failure.
In order to account for the potential differences between the actual number of trail uses and what IR counters register, an adjustment factor is used to correct the raw counts for each trail. Adjustment factors are determined by multiple hours of manual counts. To complete a manual count, a volunteer is situated within view of the IR counter and records the actual number of people who pass by the counter. The manual counts are compared to the number that is recorded on the counter for that same hour to determine the adjustment factor.
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 |
| Air Line Trail East Hampton | East Hampton | 1.30 | 1.30 |
| Air Line Trail Portland | Portland | 1.20 | 1.03 |
| Air Line Trail Thompson | Thompson | 1.92 | 1.92 |
| Air Line Trail Willimantic | Willimantic | 1.69* | 1.69* |
| Bluff Point Trail Groton | Groton | 2.37 | 2.30 |
| Charter Oak Greenway Manchester | Manchester | 1.47 | 1.49 |
| CTFastrak Trail New Britain | New Britain | 2.65 | 2.65 |
| Farmington Canal Heritage Trail Cheshire | Cheshire | 1.27 | 1.31 |
| Farmington Canal Heritage Trail Hamden | Hamden | 1.53 | 1.52 |
| Farmington Canal Heritage Trail New Haven | New Haven | 1.72 | 1.73 |
| G&S Trolley Trail Groton | Groton | 1.06 | 1.06 |
| Hop River Trail Bolton | Bolton | 1.76 | 1.71 |
| Hop River Trail Vernon | Vernon | 1.43 | 1.39 |
| Larkin State Bridle Trail Oxford | Oxford | 1.03 | 0.99 |
| Middlebury Greenway | Middlebury | 1.50 | 1.51 |
| Naugatuck River Greenway Trail Derby | Derby | 1.69 | 1.63 |
| Norwalk River Valley Trail Redding | Redding | 1.00 | 1.80 |
| Norwalk River Valley Trail Wilton | Wilton | 1.54 | 1.45 |
| Riverfront Recapture Trail East Hartford | East Hartford | 1.45 | 1.45 |
| Riverfront Recapture Trail Hartford | Hartford | 1.27 | 1.27 |
| Shoreline Greenway Trail Madison | Madison | 1.66 | 1.68 |
| Still River Greenway Brookfield | Brookfield | 1.52 | 1.53 |
| Sue Grossman Trail Torrington | Torrington | 1.64 | 1.49 |
* due to manual counts availability, the general adjustment factor from the Air Line State Park Trail Report was applied
Short-Term IR Counters 2023
| Adjustment Factors | ||
| Trail Name/Counter Location | Town | short-term 2023 |
| 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 |
| 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 |
note: unusually low or high factors can be due to low number of counts, low usage, equipment malfunction or weather related anomalies
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.
With a limited number of counters, and a lot of demand for local trail use data, CT Trail Census staff use short term counts to help local trail managers better understand use on their trails. These counts are conducted over at least several weeks to provide a good representation of hourly and daily use patterns, and comparison to similar nearby trails can allow for estimates of annual trail use.