This indicator measures traffic volumes during the winter months as a proxy for carbon monoxide concentration levels. Carbon monoxide is a public health concern because elevated concentrations affect human and animal health by reducing the supply of oxygen to body tissues. Several factors can influence traffic volumes measured on Presidents’ Day weekend, including weather, economy, and availability of alternative modes of transportation. Current programs and policies such as transit-oriented development and increasing transit service look to reduce traffic volumes. Winter traffic volume is monitored by CalTrans on Highway 50 near Heavenly Village.


Average daily winter traffic volume measured between 4 p.m. and midnight (vehicles/day) on Presidents’ Day Weekend at U.S. Highway 50 and Park Avenue, South Lake Tahoe, California.

Evaluation Map

The location of the winter traffic volume monitor on Highway 50 near Heavenly Village.

2019 Evaluation

Considerably Better Than Target
Little or No Change
View Evaluation

Applicable Standard

AQ2: Reduce traffic volumes on the U.S. 50 Corridor by 7 percent during the winter from the 1981 base year between 4:00 p.m. and 12:00 midnight, provided that those traffic volumes shall be amended as necessary to meet the respective state standards.

Key Points

  • Presidents' weekend winter traffic volumes at Highway 50 and Park Avenue have decreased significantly since 1981, and the standard has been in attainment since 1996.
  • Traffic volumes in 2020 were 43% lower than in 1981 and less than half of peak volumes observed in 1987.
  • Since the Heavenly Gondola opened in 2000, Presidents' weekend winter traffic volumes have average just over 16,000 (relative to the threshold standard of 24,000).

Delivering and Measuring Success

Local and Regional Plans

  • Main Street Management Plan

    This plan was adopted as mitigation for US 50 South Shore Community Revitalization Project. The partnership is seeking funding to implement the plan and its trip reduction measures.

Monitoring Programs