# Introduction to External Surveys
The Travel Survey Manual Chapter 15 details the methods used to conduct roadside surveys. That practice has transitioned to using blue tooth, RFID and other technologies to track vehicle movements more safely than stopping vehicles and Chapter 15 concludes with links to resources that discuss these newer methods.
In addition to directly collecting external travel, commercially available data sets are now available to supplement or complement survey data. These data sets compile data from cellular phone providers, in-vehicle GPS, and cell phone GPS to provide details of movements in, out and through regions.
This short introduction was authored by Stacey Bricka.
- Everett J, Ruegg S, & Tardiff R. Travel Survey Manual, Chapter 15.