TRJ Environmental

Time/Activity Studies and Human Mobility

City-Wide Diary Survey. Ted Johnson conducted the Cincinnati Activity Diary Study, the largest random-sample diary survey of human activity patterns in a specific urban area. This study collected 2700 person-days of detailed time/activity data -- data that have been used repeatedly by USEPA to model human activities in regulatory exposure assessments.

Data Collection by Camera/GPS System. Ted Johnson and Tom Long conducted the first field study to use a programmed digital camera and GPS system to collect personal time/activity data at one-minute intervals over 16-hour monitoring periods. They statistically compared quality of data collected by camera versus data entered by subject into real-time diary.

Longitudinal Time/Activity Data Collection. Ted Johnson is currently working with a research team under EPA STAR grant RD-83154101-0 to develop and test innovative personal monitoring technology for acquiring longitudinal time/activity data.

Radio-Monitored Time/Activity Study. Ted Johnson assisted in the design of the Los Angeles Construction Worker Study, the first time/activity study to equip construction workers with two-way radios to continuously report work activities and exertion levels.

Home-to-Work Commuting Patterns. Ted Johnson developed the algorithm employed by NEM and HAPEM to estimate home-to-work commuting patterns in urban populations.

Home-to-School Commuting Patterns. Ted Johnson developed an algorithm that can be used to estimate home-to-school commuting patterns.

Residential Occupancy Periods. Ted Johnson developed a probabilistic model for estimating the distribution of residential occupancy periods (ROP). The USEPA has used this model to generate ROP estimates for the nation. Under a recent EPA contract, Mr. Johnson evaluated alternative sources of input data for this model and developed methods for augmenting incomplete data sets.