Definitions

Annual Tons of Mobile Source GHG Emissions – GHG emissions include gases, such as carbon dioxide and methane, contributing to potential climate change. A gas that absorbs infrared radiation in the atmosphere. Greenhouse gases include but are not limited to water vapor, carbon dioxide, methane, nitrous oxide, hydrochlorofluorocarbons, ozone, hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride. For this calculation, the use of Total Annual Vehicle Miles and a multiplier provided below is applied to estimate the GHG emissions (Greenhouse Gas Emissions from a Typical Passenger Vehicle | US EPA). A Climate Adaptation Program and other groups within the area are collecting more detailed methodologies to calculate GHG, allowing for improved GHG metrics in the future.

Average Daily Traffic (ADT) This represents an estimated number of vehicles, bicycles, or pedestrian trips that interact with your zone or zones of analysis. Using the seasonal adjustment filters, the ADT output represents an estimated vehicular, bicycle, or pedestrian trip count that can be compared across time to reflect monthly, seasonal, or annual trends. With the provided dashboards, it represents an estimate of vehicles starting or stopping in the defined area.

Average Travel Time – this is the trip time for the full trip. While the duration is calculated in seconds, the distribution bins are in minutes. Additional Average Travel Time information and metrics are provided on SectionRegional Transportation Patterns.

Mode of Travel –The means by which a person or goods move. Within StreetLight Data Location-Based Services data, StreetLight currently offers the ability to study Bicycle, Pedestrian, and All Modes. All Modes include all personal travel and may include bicycle, pedestrian, vehicle, bus, etc. However, this category has a vehicular bias because its trips are locked to a vehicle road network.  Vehicles (referred to as All Vehicles within StreetLight) mode of travel uses the Location-Based Services (LBS) data source, obtained from smartphone apps that use opt-in location-based services. The LBS data contains data from people carrying their devices in whichever way they are traveling, such as in cars, trucks, on bicycles, and so on.  For LBS data, while the source is inclusive of many modes, the data source is processed with a vehicular bias. When the pings from a device create a trip, and that trip moves like a motorized vehicle, it is counted in the All Vehicle mode. For example, if the device is traveling on the road network and moves far enough for long enough, it is consistent with the movement of a car, truck, bus, or another motorized vehicle.

START Ridership – This information was collected from START operations. In the future, additional and improved data will be available as START begins to integrate improved Transportation Integrated Systems. Additional START information and metrics are provided in Section– Transit Indicators.

Travel Time Differential – The average travel time difference between the different modes (vehicle, bike, and pedestrian) of transportation to get between two locations. The StreetLight Data Insight Zone Activity Analysis was utilized for this analysis. Additional Travel Time Differential information and metrics are provided in SectionRegional Transportation Patterns.

Vehicle Miles Traveled (VMT) –  VMT measures the amount of travel for all vehicles in a geographic region over a given period of time, typically a one-year period. It is calculated as the sum of the number of miles traveled by each vehicle (StreetLight Data). This metric is provided for annual and seasonal time periods within the boundary of Teton County and the Town of Jackson. The StreetLight Data Insight Zone Activity Analysis was utilized for this analysis. A Zone Activity Analysis calculates the average trip length and average daily zone traffic. This includes all trips that start and end in the zone, regardless of either origin or destination. Below is the calculation used to generate VMT. Additional VMT information and metrics are provided in Section – Regional Transportation Patterns.

Total Vehicle Miles Traveled per time period = 

Avg All Trip Length (mi) x Average Daily Zone Traffic (StreetLight Volume) x number days within time period