Research Note 95-12 - Workweek Alterations and Employee Travel

No. 95-12
June 1995
California Environmental Protection Agency Brief Reports to the Scientific and Technical
Air Resources Board Community

Research Division, John R. Holmes, Ph.D., Chief P.O. Box 2815, Sacramento CA 98512

Effects of Compressed Work Week on Employee Travel

The objective of this study was to estimate the net trip and mileage benefits of the compressed work week, taking into account the possibility that employees engage in driving activities on their days off. Results showed that employees on compressed work week reduce their number of trips by 0.5 to 0.8 and their miles travelled by 13 to 20 per week as compared to employees on regular five-day work weeks. This study was performed by the University of Southern California.


Many businesses in California offer compressed work week to their employees to help reduce traffic congestion and auto emissions. Typical compressed work weeks consist of four ten-hour days in one week (4/40) or nine days (80 hours) over a two-week period (9/80). However, the net reduction in congestion and emissions is less than the maximum possible because some employees drive on their days off. This study was performed to estimate the net impact of compressed work week plans on vehicle miles travelled.
Methods: About 2,600 southern California employees were surveyed for information on their occupation, travel habits, and socioeconomic characteristics. About 530 of the employees were more intensively surveyed with a seven-day trip diary in which they recorded their work and non-work trips. Half the sample consisted of employees on compressed work week and half on a regular five-day, forty-hour work week. A trip was defined as any segment of travel with a specific purpose in mind.
Results: Employees using a compressed work week schedule tend to be males between 25 and 54 years old from single-worker households. Trip distance to work is statistically the same for those on compressed schedules and those on regular schedules. Forty-three percent of the respondents owned one car per household. Forty percent owned two, and 16% owned three or more. Fifty-three percent of trips were driven alone and 26% with a passenger. A fairly significant portion of trips, about 6%, were walking or jogging trips.

Employees on compressed work week reduced their net number of trips by an average of 0.5 per week. A "trip" ended at the point at which a passenger or the driver left the car, and did not necessarily begin at the home. Calculated on a home-to-work basis, the weekly average net reduction was 0.8 trip. More important than the reduced number of trips is the fact that these trip reductions tended to occur at the morning and afternoon peak periods. Trips on the day off tended to occur at non-peak periods, benefiting air quality and reducing congestion during peak times. The respondents using a 9/80 schedule drove an average of 13 fewer miles per week; those using a 4/40 schedule drove an average of 20 fewer miles per week.

The number of employees participating in compressed work week programs is surprisingly low, even though many employers offer that flexibility. This may indicate that barriers to widespread implementation exist. Barriers to compressed work week were beyond the scope of this study; this is a subject for further investigation.
Significance and Application: Several air quality districts plan for and rely on alternative transportation modes and schedules to reduce mobile source emissions and attain air quality standards. The effectiveness of the alternatives significantly impacts the planning options. This study will help ARB evaluate the transportation portion of air quality plans.
Related Projects: The ARB has sponsred two projects that evaluate the effects of incentives to reduce driving (ARB contract numbers in parentheses): Evaluating the Effects of Parking Cash-Out (93-308) and Air Quality, Congestion, Energy, and Equity Impacts of Market-Based Transportation Control Measures (92-316). Other research includes Effects of Increased Highway Capacity on Vehicle Trip Generation (92-325); Analysis of Indirect Source Trip Activity, which analyzes and quantifies transportation control measures for regional shopping centers (A132-094); Incentives for Trip Reduction Through Location of Housing near California Rail Transit Stations (A032-185); and A Survey and Analysis of Employee Responses to Employer-Sponsored Trip Reduction Incentives Programs (A932-187).

This research was conducted under contract with the University of Southern California (ARB Contract No. A132-136). Comments or questions can be directed to the contract manager, Fereidun Feizollahi, by mail, FAX (916) 322-4357, phone (916) 323-1509, or e-mail: For an index of Research Notes, call (916) 445-0753 or FAX (916) 322-4357.
Copies of the research report upon which this Note is based can be ordered from:
National Technical Information Service
5285 Port Royal Rd
Springfield VA 22161
Request NTIS No. PB95-179560
Title: Impacts of Compressed Work Week on Total Vehicle Trips and Miles Travelled
Author: Genevieve Giuliano