Interstate 80/State Route 65 Interchange

The Project

The Interstate 80 (I-80)/State Route 65 (SR 65) interchange in Roseville, California is a vital link of two highly-traveled freeways in the heart of South Placer County. Highway 65 serves the growing communities of Lincoln, Rocklin, and Roseville while I-80 is a key commute and goods movement corridor. Traffic within the area is fairly congested especially during peak hours and is getting worse.

The Placer County Transportation Planning Agency (PCTPA) asked us to prepare the transportation analysis for the project approval and environmental document (PA&ED). The large study area includes 19 miles of freeway, five interchanges along I-80, eight interchanges along SR 65, as well as the local connecting and parallel arterial system.

Our Use of Data Science

We worked with Mygistics and PTV in using Airsage data (cell-phones) and TomTom GPS data (travel time and speed) to develop an integrated set of travel demand and traffic operations models tailored to the study corridor.

This type of data provides us the ability to observe actual origin-destination patterns and even travel paths, which improves model accuracy and helps elevate the level of confidence in the model results. Traditionally, our industry builds models using synthetic data instead of observed data, and uses estimates from travel demand models that are typically developed based on a limited sample of household travel surveys conducted over 1 or 2 days.  With big data, we were able to capture the origins and destinations of 128,000 anonymous cell phone users for an entire month, resulting in 92 million data points.


Our innovative use of this data enabled us to quickly build VISUM and VISSIM models that more accurately evaluated travel patterns and responses to network changes.

We also used the VISSIM model to create detailed traffic operations analysis of freeway interchange alternatives, produce 3-D visual simulations and help communicate analysis results to the public and the reviewing agencies. Both models passed all required Caltrans and Federal Highway Administration validation tests in about half the time of conventional model building.

The PCPTA project team was much more confident in our models (compared to those using traditional methods) because of the robust and accurate big data foundation. This confidence led to greater use of the models in the alternatives development, and made Fehr & Peers an even more integral part of the design process.

Confidence from this project led to…

Use of the models in the alternatives development

Fehr & Peers becoming an even more integral part of the design process