BP Multi sensor along the bike path. The sensor counts bikes and people passing by.
How it Works:
There are six counters placed throughout the reservation. Two are located along the Perimeter Road: one at the water treatment plant (WTP) and the other near Little Fresh Pond (LFP). There are also sensors at popular entrances to Fresh Pond: Black's Nook, Lusitania, and the hill by the golf pro shop. These entrance sensors will help us understand where the majority of users are coming from, and whether they are commuting through or here to recreate. An additional sensor capable of counting bikes and people was installed on the bike path along Fresh Pond Parkway. The Eco-Counters tally both the number and direction of users by using a passive infrared sensor and a lens to detect small temperature changes caused by people passing the sensor. The sensors collect no other information. For quality control, data from the Eco-Counters is downloaded weekly and screened for anomalies. Staff and volunteers conduct surveys of user type, group size, and travel direction periodically at Eco-Counter sensor locations. These surveys function to supplement and quality check the data collected from the Eco-Counter sensors.
Last year an average of 37,300 people passed the sensors on the perimeter road of Fresh Pond Reservation every month
, and an average of about 1,200 people every day
. See the graph below for monthly counts from sensors at the Water Treatment Pant and Little Fresh Pond in 2016. For detailed results, view the annual summary: Fresh Pond Census Annual Report 2016
The data collected from the Eco-Counters is compared to tallied counts of walkers, runners, and cyclists from visual surveys done by staff and volunteers. This ability to compare what the sensors recorded to actual observations is essential for ensuring we can trust the data we collect. The running average error between the sensor counts and survey data is approximately 13%, the majority of which is attributed to differences caused by side-by-side groups the sensor detects as one count. Reservation users who are shorter than the height of the Eco-Counters, such as children and dogs, are not tallied by the Eco-Counter and thus not included in the error calculation. Comparisons between the surveys and sensor results imply that the sensors consistently underestimate total user amounts, indicating that the Eco-Counters provide conservative estimates of reservation usage. User type data collected from 2016 surveys, shown in the pie chart below, indicates that nearly half of all users at the Reservation are walkers, while approximately 20% are dogs. These data help us inform our shared use management strategies. If you like what you hear, consider volunteering as part of our census team!