alt definitions

VisionEval Definitions

FUTURE: TARA merge with definitions page. Delete what is not used. This is a dump of shorter definition lists than the original definitions list. This also includes a more comprehensive list of terms to include, and possibly some add'l definitions.

Future possibility: Add links to deeper docs within VE repos

This document summarizes the VisionEval definitions, organized into thematic areas. Collectively these provide a lexicon of the concepts and terminology used in VisionEval. It is designed to be used in conjunction with the VisionEval concept primer rather than a standalone document. However, one can learn quite a bit about the architecture and functionality of VisionEval by skimming through this document.

Terms are alphabetized within each of the major thematic areas below. Searching this page may be the quickest way to find specific items, as terms are alphabetized within each of five major thematic areas below:

1. VisionEval Geography
2. Household Synthesis & Land Use
3. Household Multi-modal Travel
4. Vehicles, Fuels & Emissions
5. Congestion
6. Household Costs & Budgets

1. VisionEval Geography

• Region: The region defines the entire modeled area represented in the model. There is no limit to the size of the modeled region, although sub-state areas, states, and megaregions are often simulated using VisionEval.
• MAreas: Metropolitan areas are defined within the model-wide Region. The primary benefit of doing so is to enable the coding of transit systems with higher levels of service and accessibility and to denote higher levels of background congestion.
• Bzones: The smallest levels of geography coded in VisionEval, and often correspond to Census tracts or block groups. In most instances the Bzones are larger than traffic analysis zones used in traditional travel demand forecasting models.
• Azones: Optional aggregations of Bzones, often corresponding to county, city, Census named place, or comparable political divisions.

2. Household Synthesis and Land Use

• 5D variables: Built form variables relating to housing density, land use diversity, destination accessibility, and neighborhood design, demographics and employment, and transit service proposed by Ewing & Cervero (2001, 2010). These variables are used to measure the relative efficiency of a location, particularly with respect to smart cities visions. These variables are coded at the Bzone level, and correspond to definitions found in the EPA Smart Location Database.
• Age groups: VisionEval classifies persons in the population as a child (0-10 years old), teenager (11-19 years old), young adult (20-44 years old), mid-life (25-64 years old), and seniors (65+ years old).
• Auto ownership cost:
• Built form 'D' variables: see 5D variables
• Car service: // Low and High service, including taxis, car sharing services (e.g. Car-To-Go, Zipcar), and future automated taxi services.
• Census PUMS: see Public Use Microsample
• Developable land area: The amount of developable land area within a Bzone in acres. This can include vacant and under-developed land, as well as land available for reconstruction. The area calculation should exclude public spaces (e.g., parks, public buildings) and natural features such as water and ravines.
• Dwelling Unit Types: Each synthetic household occupies a single family or multi-family dwelling, or is part of group quarters (GQ).
• Employment Rate: The employment rate is the number potential workers aged 17 and over divided by the total number of persons in the Bzone. Note that it is a calculated rate based on zonal attributes, and is a proxy for the labor force participation rate.
• Employment Types: Employment is classified as Total, Retail, or Service. Retail employment corresponds to NAICS sector 44-45, while Service corresponds to sectors 51-81. The Total employment includes all sectors, to include Service and Retail.
• Household Types: Household are classified as either a regular household or unrelated persons living in non-institutional group quarters. The Household type describes the type of household in terms of the interpersonal relationships, while Dwelling type describes the type of structure that the household occupies.
• Licensure Rate: The percent of adults aged 17 and over that possess a drivers license, summarized from the PUMS data for the modeled region.
• Location Types: Each home and work location is labeled metropolitan, town, or rural.
• Mean income: The mean household income by Azone is compiled from Census data.
• National Household Travel Survey (NHTS): The NHTS is conducted periodically by the Federal Highway Administration to collect household, traveler, and travel diary information from households across the nation. Data from the 2001 NHTS has been used to develop the travel demand rates and distributions used in VisionEval.
• Parking restrictions and Parking Fees: // including workplace parking cash-out-buy-back program
• Per Capita Income: // Annual household
• Public Use Microsample (PUMS): The PUMS data are untabulated and anonymized person and household records with individual responses coded in the Census, to include age, employment status, etc. Multi-dimensional summaries of these data are used in population synthesis and to create travel and vehicle use statistics used in VisionEval.
• Short Trip diversion:
• Transit service level:
• Travel Demand Management programs: Both home-based Individualized Marketing Programs (IMP) and Work-based Employee Commute Options (ECO) programs can be coded.
• Worker parking cash-out program: // .xxx

Unresolved:

• Urban MIXED USE. xxx [based on NHTS2001 definition]

3. Household Multi-Modal Travel

• Household DVMT by percentile: In addition to average day (7 days), VisionEval estimates DVMT for each 5% percentile (e.g. 5th percentile, 10th percentile, 15th percentile, etc.) as well as the 99th percentile. This is used to help identify whether an EV vehicle is feasible for this households typical travel. (Note that this module estimates household vehicle travel regardless of where is occurs (i.e. outside the model region as well as inside the model region). The calculations of DVMT on roadways within urbanized areas, for the purpose of calculating congestion and its effects, are carried out by the CalculateRoadDvmt module in the VETravelPerformance package. Household vehicle travel includes travel using car services.)
• Household VMT: // - (auto and car share)
• Lifecycle: // (aggregated NHTS definition) – used in multi-modal travel module
• SOV diversion: Qualifying SOV tours (i.e. round trip tours 20 miles or less in length). This allows evaluating the potential for light-weight vehicles (e.g. bicycles, electric bikes, electric scooters) and infrastructure to support their use in reducing SOV travel. Bikes represent this diversion in the outputs, but could be other light-weight vehicle modes.
• Transit Bus equivalent-miles: Revenue miles are adjusted to bus-equivalent (i.e. mode MB) miles (e.g. ratio of , to better reflect the service level experienced by a transit rider (i.e., light rail attracts more riders per in-service mile than demand-responsive service)
• Transit D: Weekday PM Peak Period visits by transit service within 0.25 miles.
• Transit Revenue miles: In-service revenue miles, as defined by National Transit Database. VisionEval estimates dead-heading when not in service, which are added to cover all miles when estimating emissions and congestion.
• Transit Service Modes: Transit Service is characterized by 8 modes: demand responsive (DR), Vanpool (VP), Buses (standard motor bus MB, Rapid-Commuter RB), Rail (Monorail MG, Streetcar SR, Heavy-Light Rail HR).
• Transit Vehicle Types: The transit vehicle types include van (modes DR, VP), bus (modes MB, RB), and rail (modes MG, SR, HR).
• Travel Demand Management program: see Travel Demand Management
• Value of Time:

4. Vehicles, Fuels, and Emissions

• Vehicle Groups: VisionEval includes the four several vehicle groups listed below. Light duty vehicles are further split by [Vehicle Type]. Fuel consumption and emissions from car services are calculated in conjunction with household vehicle emissions and are attributed to the household.

  • Household vehicles, including CarService vehicles are considered light duty (roughly less than 5,000 pounds).
  • Commercial Service Vehicles represent local delivery within Metropolitan areas only, and are assumed to be light duty, but may contain some medium duty (roughly up to 26,000 pounds).
  • Heavy trucks, represent intercity long-haul freight, and are considered heavy duty (over 26,000 pounds).
  • Transit Buses are heavy duty, but transit vans are light duty.

• Vehicle Type: Light duty vehicles consist of a mix of Light trucks including pickup trucks, sport utility vehicles, vans, and any other vehicle not classified as a passenger car light truck. All others are assumed to be automobiles. User inputs must be consistent with assumptions in default package data, which currently uses this definition.

• Vehicle Table: One record for each household of working age [or worker?]:

  • "Owned" for access to vehicles owned or leased by a household, with attributes of vehicle type and average vehicle age.
  • Car Service Level: Either “LowCarSvc” or “HighCarSvc”, based on coverage in the home Azone, for workers without an owned vehicle.
  • Time-to-access vehicle: Attribute of owned and CarService vehicles, representing the time to // ...
  • Powertrains: Internal combustion engine vehicle (ICEV), hybrid electric vehicle (HEV), plug-in hybrid electric vehicle (PHEV), and battery electric vehicles (BEV).
  • Fuel efficiency: Default inputs are in miles per gallon (MPG) and miles per kilowatt-hour (MPKWH) (or often more convenient gallons per mile (GPM) and kilowatt-hours per mile (KWHPM)), as well as calculations of miles per gasoline gallon equivalent (MPGe). Statistics are also kept on the VMT powered by hydrocarbon fuel versus electricity.
  • Fuel blend: Specifies the proportions of gasoline blended with ethanol, biodiesel blended with diesel, renewable natural gas is blended with natural gas
  • Carbon intensity: The carbon intensity of fuels are expressed in grams of CO2e per megajoule

Note that energy consumption is calculated in gas gallon equivalents (GGE) or kilowatt hours (KWH) (or both in the case of PHEV). Both are converted to equivalent megajoule (MJ) energy values within VisionEval.

5. Congestion

• Congestion levels: VisionEval uses congestion levels defined in the 2009 Urban Mobility Study by the Texas Transportation Institute, Exhibit A-6. The 2009 report's data-relationships used in VisionEval are included in the VETravelPerformance documentation and embedded graphics.
• Growth basis: //define, and give options
• Road class: The proportion of lane miles that are classified as freeway, arterial, other. This is coded separately for the modeled Region and for MAreas within it. The former is used for all non-metropolitan areas.
• Urbanized area: // define as used in CalculateRoadDvmt modulexxx

6. Household Costs and Budget

• Car service substitution probability: Average likelihood that an owner would substitute car services for a household vehicle (separate values by Vehicle Type. For example, if the user assumes that only a quarter of light truck owners would substitute car services for owning a light truck (e.g., because car services wouldn't enable them to use their light truck as they intend, such as towing a trailer), then the light truck substitution probability would be 0.25.
• OwnCost: The amount each household pays each year to own their vehicles. It is the sunk cost they ‘pay’ each year as opposed to the variable cost that they pay for each mile that they drive. The OwnCostSavings (separate output) is the ownership cost that they saved by substituting the use of car services for owning a vehicle. The module documentation describes how the decision is made to drop (or no) one or more cars from a household inventory if car service costs are price competitive.
• Passenger car equivalent (PCE): The number of light-duty vehicles a heavy truck is equivalent to in calculating road capacity.
• Vehicle operating cost: This includes out-of-pocket costs (used in household budget model), which include ...

Unsure how to untangle this (part of vehicle operating cost...) While composite operating costs add time-equivalent cost of travel: Fuel (energy), Veh operations (Maintenance, tires and repairs, Pay-as-you-drive insurance mileage fee), per mile fees (Gas and Road use taxes, Pollution taxes (e.g. carbon tax)), Parking charges, and car service fees. Some new terms include:

• Access Time. average amount of time spent on each end of the vehicle trip (owned or Car Service) to get from the origin to the vehicle and from the vehicle to the destination
• Social Costs, including Cost of Carbon and other social costs. Input identifies portion paid by drivers.
• Electric Vehicle surcharge. Equivalent fuel tax paid per mile for vehicles that don't purchase fuel. Input identifies portion of EV [or PH/EV?] vehicle miles subject to the fee.

• Vehicle ownership costs: Includes financing, depreciation, insurance (unless in PAYD program), annual registration fees, and residential parking fees.

Pending definitions

These have been identified as important to include, but which of the above sections they should be added to has yet to be decided:

• Access time includes the time to get from the origin to the vehicle (or in the case of taxi or TNC, the time for the vehicle to get to the traveler) and the time to get from the vehicle to the destination (including time to park the vehicle). Covers Owned and Car Service (high and low service levels) in units of minutes per trip.
• ArtLnMiCost: Average cost to build one arterial lane-mile (dollars per lane-mile).
• CO2eCost: Environmental and social cost of CO2e emissions per metric ton. in file [region_co2e_costs.csv]
• FuelCost: Retail cost of fuel per gas gallon equivalent in dollars.
• FwyLnMiCost: Average cost to build one freeway lane-mile (dollars per lane-mile).
• HvyTrkPCE: Passenger car equivalent (PCE) for heavy trucks. PCE indicates the number of light-duty vehicles a heavy truck is equivalent to in calculating road capacity.
• PevSurchgTaxProp: Proportion of equivalent gas tax per mile paid by hydrocarbon fuel consuming vehicles to be charged to plug-in electric vehicles per mile of travel powered by electricity.
• PowerCost: Retail cost of electric power per kilowatt-hour in dollars.
• PropClimateCostPaid: Proportion of climate change costs paid by users (i.e. ratio of carbon taxes to climate change costs).
• PropOtherExtCostPaid: Proportion of other social costs paid by users.
• RoadBaseModCost: Average base modernization cost per light-duty vehicle mile traveled (dollars per vehicle mile). Base modernization includes roadway improvements exclusive of addition of lanes.
• RoadPresOpMaintCost: Average road preservation, operations, and maintenance cost per light-duty vehicle mile traveled (dollars per vehicle mile).
• RoadOtherCost: Average other road cost (e.g. administration, planning, project development, safety) per light-duty vehicle mile traveled (dollars per vehicle mile).