Helping SANDAG Evaluate Travel
Before and After a High Profile Decision

Our Innovative Use of Data

Our innovative use of GPS and cell phone data helped us quickly perform a before and after study that provided the San Diego Association of Governments (SANDAG) with the information they needed to help determine if they made a wise decision in a major infrastructure investment.

Unlike GPS and cell phone data, traditional data are not often able to evaluate before and after metrics due to availability, cost and sample size. They also lack the ability to anonymously isolate individual travel patterns. Our knowledge of new technology and the resulting products developed in partnership with StreetLight Data helped us deliver the information SANDAG would not be able find elsewhere.

The Project

To help alleviate traffic on I-805 and avoid building a full-four lane expansion that would have taken decades and cost taxpayer millions for construction costs, SANDAG acquired SR 125 (also known as the South Bay Expressway), a private toll-road running north-south along the eastern side of the region. The agency then reduced tolls to encourage drivers to shift from I-805 to the expressway.

 

The Need

A year later, SANDAG wanted to know how many drivers switched from I-805 to the expressway after the toll reduction.

 

Our Solution

In the past, data sources only allowed us to provide counts and often did not go back in time for travel patterns. For this project, we were able to use GPS data to provide analysis that showed relative shares of traffic on both the expressway and the interstate before the toll reduction and then after the reduction had been in place for a few months. By comparing which routes people were taking we were able to illustrate a clear statistical shift in drivers’ behavior and how it differed for weekday commuting versus weekend activities, and northbound versus southbound trips.

We were also able to distinguish between fleet and passenger vehicles which is important because the data would’ve otherwise been skewed and not shown the significant shift in driving behavior.

 

Results

This type of data collection and analysis would normally not be possible or would have taken many months. However, because of our expertise and the relationships we have with our teaming partners, we obtained, processed, reviewed and delivered the data and a PowerPoint presentation summary with easy to understand graphics and talking points within the two-month schedule. Our client’s response – “We know we gave you a tough project and you delivered.  Thanks you!”