Indicator
Vehicles Miles Traveled per Capita
2023 Evaluation
View in Threshold Dashboard

The Transportation and Sustainable Communities threshold standard was adopted in April 2021 and established a target of reducing vehicle miles traveled (VMT) per capita in the Tahoe Region by 6.8 percent from a 2018 baseline (12.48 VMT per person). VMT is the total distance traveled on roadways in a defined region during a period of time. Capita is a measure of the population in the region. Tahoe uses an estimate of all people in the region to calculate VMT per capita, inclduing residents, visitors, seasonal residents, day visitors, and workers on an average day.Reducing per capita VMT requires coordinating land use and transportation planning. On the land use side, VMT per capita can be reduced by promoting compact, mixed-use development where people live and stay closer to jobs, recreation areas, schools, and services. On the transportation side, reducing VMT per capita can be achieved by providing alternatives to the automobile for making trips, including transit and improving walking and cycling infrastructure. Achieving the standard will reduce visitors' and residents' reliance on automobiles and result in nearly zero growth in VMT over the next 25 years. The adaptive management framework provides for independent guidance and contains a set of VMT per capita reduction milestones that require corrective action if performance lags.

Al_Tahoe_Bike_Trail_2011cr.jpg

Al Tahoe Bike Trail.

Status

The TRPA Governing Board adopted the VMT per capita threshold standard in April 2021.

  • The standard is evaluated using VMT as reported through the Highway Performance Monitoring System (HPMS) by CalTrans (https://dot.ca.gov/programs/research-innovation-system-information/highway-performance-monitoring-system) and NDOT (https://www.dot.nv.gov/doing-business/about-ndot/ndot-divisions/planning/roadway-systems/annual-vehicle-miles-of-travel), and the effective population of the region as estimated with the Tahoe Effective Population Model ( Tahoe Effective Population Model (TEPM) )
2023 Evaluation
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Status
At or Somewhat Better Than Target
Trend
Insufficient Data to Determine Trend
Confidence
Moderate
Applicable Standard
TSC1: Reduce Annual Daily Average VMT Per Capita by 6.8% from 12.48, the 2018 baseline, to 11.63 in 2045
Key Points
  • Between 2018 and 2022, VMT per capita declined between 9 percent and 26 percent .
  • Three-year average VMT in the Tahoe Region dropped 13 percent between 2018 and 2022.
  • The resident population in Tahoe as reported by the US Census has been stable for the last 20 years.
  • COVID-19 and it’s restrictions were a major disruption to life and travel patterns that very likely led to a short-term decline in vehicle travel and visitation to the Region.
  • Implementation of the Regional Transporation Plan and Regional Plan will reduce VMT per capita throughout the region by centralizing development and providing alternative modes of transporation like bike and walking paths and transit.  
About the Threshold

TRPA adopted Transportation and Sustainable Communities Threshold Standard 1 (TSC1) in April 2021, codifying a new goal for the reduction of VMT per capita. The threshold standard aligned the vision of the Regional Transportation Plan (RTP) and the TRPA Regional Plan to reduce reliance on the automobile, support greenhouse gas emission reduction, and increase mobility through modes other than the automobile. Coordinated land use through the Regional Plan) and transportation through RTP policies are central to achieving the threshold standard.

VMT per capita is a measure of interaction between land use and the transportation system and its efficiency in moving individuals between the places they need to be. Higher VMT per capita regions are those where individuals are traveling farther distances to get between home, work, shopping, etc., and are generally reliant on the automobile to move between destinations. Lower VMT per capita regions are those that are characterized by individuals traveling shorter distances between their destinations and where there are options for travel other than the car (e.g. bike paths, transit systems) that are chosen more frequently as a means of taking those trips.

VMT can be expressed in absolute terms (total miles traveled) or as a function of another factor (e.g. per worker, or per residents). The latter are collectively referred to as efficiency-based measures. Efficiency-based measures express the amount of VMT in a region as a function of a factor thought to be related to that VMT. One of the most common efficiency-based measures is expressing VMT in a region as a function of the region’s population.

Vehicle miles traveled (VMT) is a measure of the number of miles driven on roadways in a specified area over a specific period of time. VMT is a function of the complex interplay of a variety of factors including: population (both inside and outside the region), gas prices, employment rates, local housing costs, demand for recreational opportunities in the region, access to alternative forms of transportation, and secondary home ownership. Increased congestion, work-from-home programs, employer carpool programs, concentration of development in town centers, presence of travel alternatives, higher unemployment, and higher fuel prices are all linked with a reduction in VMT. Population growth, higher household income, higher employment rates, increased fuel economy and greater roadway capacity are all linked to increasing VMT. Increasing access to transit services, access to bicycle and pedestrian facilities, and the relative desirability of alternative modes of transportation in comparison to the use of the personal automobile may reduce VMT.

Delivering and Measuring Success

EIP Action Priorities

Example EIP Projects

Local and Regional Plans

Rationale Details
At or Somewhat Better Than Target. VMT per capita declined between 2018 and 2022 by between 8.8 percent and 26.1 percent.

The standard uses a three-year average VMT as the basis for assessment to insulate it from variation in VMT related to exogenous factors known to influence annual VMT. A comparison of the 3-year average VMT from the earliest period on record (2016 to 2018) suggests that VMT has decreased by 5.5 percent between 2016 and 2022. The decline in VMT during that period is concentrated on the California side, which declined from just over a million to just over 850,000 VMT. On the Nevada side, VMT has remained stable.

The second component of VMT per capita is an estimate of the total population of the Region, including residents, visitors, seasonal residents, day visitors, and workers on an average day. When the standard was adopted, the Region worked with the Tahoe Science Advisory Council to develop the Tahoe Effective Population Model (TEPM). The TEPM estimates the number of people present in the Lake Tahoe Region on an average day using information drawn from a variety of sources, including U.S. census data on population, traffic counts at external gateways, tax returns for lodging occupancy, and survey data on travel patterns. The first input of the effective population is the resident population. Over the past decade, Tahoe’s resident population has remained relatively stable. The U.S. Census estimated the population increased by 230 residents between 2010 and 2020. The annual estimates of the American Community Survey between 2010 and 2022 also suggest there has been a minimal population change.

The 2018 TEPM estimate used StreetLight Data, Inc. (StreetLight) estimates of entry volumes. TRPA has engaged with StreetLight to acquire more recent estimates to recalculate the effective population. Because the effective population estimate of the TEPM is calibrated based on entry-exit volumes to the Region, it is highly sensitive to variability in the estimate and thus requires a consistent data source to produce comparable estimates. In 2018, StreetLight's estimated entry volumes were 10 percent lower than the Department of Transportation (DOT) estimated volumes. In 2021, StreetLight-estimated entry volumes were 11 percent higher than DOT estimated volumes. Notably StreetLight-estimated volumes increased by 16 percent while DOT estimated volumes declined by 6 percent.

Holding all other inputs constant results in an effective population of 134,692, more than 14,000 higher than the StreetLight-derived estimate. Using DOT estimated volumes for 2022 and the updated inputs referenced above, the effective population in 2022 would be 131,369, 2.5 percent lower than in 2018.
Given the complexity of estimating the effective population through the TEPM, TRPA has been exploring other methods of estimating the effective population. Many big data platforms exist to track visitation and foot traffic to businesses and major destinations, including the Tahoe Region. One such platform, Placer Labs, Inc. (Placer.ai), has been obtained by TRPA to evaluate its performance in the region. The effective population based on the TEPM for 2018 was 118,856, while Placer.ai suggests the population was 166,983. The reduced computational burden would enable the use of a three-year average effective population, which would align with the three-year estimate of VMT. The three-year average effective population as estimated from Placer.ai is summarized in the attached data and suggests a slight (4% percent) decline in the average number of people in the Tahoe Region over the last five years.

Integrating the individual effective population estimates with VMT, there are three estimates for change in VMT per capita between 2018 and 2002:
• TEPM- Streetlight: 26 percent decline
• TEPM-DOT: 11 percent decline
• Placer.ai: 9 percent decline
Insufficient data to determine trend. The decline in VMT and VMT per capita is driven largely by a decline in VMT on the California side. Staff are working with the California Department of Transportation (Caltrans) to validate that the estimated decrease on the California side is a decrease and not a modeling artifact. The decline in VMT on the California side corresponded with the COVID-19 pandemic, but unlike in Nevada where counts and VMT rebounded nearly to pre-COVID levels, the same pattern is not visible on the California side of the Region, where VMT has remained lower than pre-COVID levels through 2022. The COVID-19 pandemic altered travel patterns throughout the country and the world. Many areas saw disruptions in travel patterns as a result of COVID-19; while many of those have reverted to pre-COVID norms, some, including higher work-from-home rates, have remained. The trend will be assessed in future years to see if the impacts of COVID are lasting or if the observed decline was a result of the pandemic.
Confidence Details
Moderate. Data to assess VMT is drawn from the Highway Performance Monitoring System (HPMS), that follows consistent reporting guidelines. This data is available from each DOT on the tables that summarize Miles, Lane Miles and Daily Vehicle Miles of Travel by Metropolitan Planning Organization. The latest data reported for each state is 2022. For additional detail on HPMS see: https://www.fhwa.dot.gov/policyinformation/hpms.cfm Estimation of the effective population of the Region was completed with the Tahoe Effective Population Model (TEPM) and Placer.ai.

Details of individual calculations are available on the "VMT per capita calculations" spreadsheet link at the bottom of the page.
Insufficient data to determine trend.
Moderate.
Additional Figures and Resources

No photos available.

VMT per capita calculations.
Uploaded On
10/2/2024
File Type
Excel (XLSX)
Description
Calculation details and inputs to the Tahoe effective population model used to calculate VMT per capita for the 2023 Threshold Evaluation.
Transportation: A Bi-State Commitment to Improving Lake Tahoe
Uploaded On
9/3/2024
File Type
PDF
Description
Bi-State commitment to augmenting transportation funding.