Impacts of Connected Vehicles on Multimodal Geometric Design

The following is an excerpt of an article, published in August 2017 by Transportation Management & Engineering (TM&E) magazine, written by Brian Ray, a professional engineer (PE) in Kittelson’s Portland, Oregon, office. A link to the full article follows this excerpt.

Roadway and highway designers have been increasingly turning from dimensional-based, three-dimensional geometric design criteria to performance-based analysis approaches. Historical approaches of using vehicular capacity and meeting nominal design criteria are giving way to multimodal solutions established via performance-based evaluations to guide project decision making.

“Performance-based practical design” has been embraced by the Federal Highway Administration (FHWA) and is being integrated by many transportation agencies to quantify and/or support project design decisions. Performance-based approaches recognize designers must consider various users and balance the needs and performance for each unique context. Our industry is increasingly considering factors beyond capacity-based mobility to guide project decisions and multimodal quality of service, and quantitative safety performance measurement is central to evolving roadway design activities.

Transportation safety, as measured by crash frequency and severity, is a continuum, not an

Interest in connected and automated vehicles (CAVs) is advancing as fast as the technology associated with smart vehicles and infrastructure. CAVs ultimately will result in measureable benefits in traffic safety and efficiency, but the actual implementation of self-driving, fully automated vehicles will occur incrementally over time. The sequence will generally range from “connected drivers” (smartphones and crowd-sourced traffic applications, such as Waze) to “automated vehicles” where computers replace or augment human driver vehicle operation and control (e.g., adaptive cruise control). Autonomous vehicles are intended to incorporate connectivity and/or automation to allow vehicles to operate with little to no human assistance.

Fundamentally, roadways have been designed for human beings by providing predictable and consistent features to meet user expectations and avoid conflicts. In time, CAVs and technology integrated in roadway infrastructure may result in future designers applying criteria meant to serve vehicles and technology. Until that time comes, our geometric design approach and criteria will remain focused on meeting the needs of human beings, adapting incrementally over time commensurate with technological advances that result in safety and operational benefits.

Read the complete article on the TM&E website.