In April, 1991, the Southern California Association of Governments (SCAG), contracted with the Applied Management & Planning Group to conduct an origin-destination survey of 15,700 households. This was the first such survey conducted in the region since a 1976 SCAG study. A statewide origin-destination survey, sponsored by Caltrans was conducted concurrently with the SCAG study.

The 1991 Southern California Origin-Destination Survey was coordinated and managed by SCAG for the following five agencies representing their respective counties in the SCAG region:

  • Los Angeles County Transportation Commission,
  • Orange County Environmental Management Agency,
  • Riverside County Transportation Commission,
  • San Bernardino Associated Governments,
  • Ventura County Transportation Commission

The sixth county in the SCAG region, Imperial, chose not to participate.

The goal of the 1991 Southern California Origin-Destination (Q-C) survey was to provide SCAG and the five participating county transportation agencies with information regarding the travel of a sample of 15,700 households. The travel information was collected using a one-day, activity-focused diary, in five languages: English, Spanish, Vietnamese, Chinese and Korean. Travel information was obtained from all persons aged five or older in sampled households through a Computer-Assisted Telephone Interviewing (CATI) system. .

The survey was designed and managed by the Applied Management and Planning Group (AMPG); the telephone contact with participating households was conducted by AMPG's major subcontractor, the Interviewing Service of America (ISA).

Briefly, the survey procedures were:

  • Recruitment - Households were recruited by telephone, and participating households were assigned a diary day that was the same day of the week as the telephone call. During the recruitment call, the characteristics of the household were obtained, including household size, vehicle ownership and housing type, in order to place the household in the correct cell of the sampling matrix.
  • Materials Mailing - The day following recruitment, the AMPG team mailed a package to participating households containing: a cover letter from SCAG introducing the study, a household information form, a -One-Day Diary for each member of the household five years of age or older, and a $1 incentive.
  • Reminder Call - The night before their assigned diary day, each household was telephoned to verify that they received their package of materials, remind them of the survey, answer any questions they may have, and set an appointment for retrieval of survey information.
  • Retrieval Call - During the retrieval call, the household form and diary information was collected for all members of the household. Since the Calls were made using CA TI, the data were simultaneously entered into a data base.
  • Reward - To encourage cooperation, we provided a $1 incentive with the initial mailing of the one-day diaries. and provided a $2 cash bonus after retrieving all information from the household. In addition, SCAG provided press releases, public service announcements, and assisted in placing newspaper articles to publicize the survey.

The survey included weekday information only. and an attempt was made to balance the diary. days across all five days of the week. A household was considered complete if it included the following, as per the Caltrans definition:

1. Every activity made on the specified diary day by each member of the household five years of age and older including the following:

  • Where each activity began and ended;
  • The mode of travel used for each activity;
  • The activity purpose;
  • The beginning and end time of each activity.

2. The number of persons in the household;

3. The number of vehicles owned or used regularly by household members;

4. The type of housing unit they live in.