TTI Competitive Research Program 2016

2016 Awardees:


Marcus Brewer                                          
Associate Research Engineer                               

Shannon Barkwell

Project Title: Exploration of the SHRP2 Naturalistic Driving Study Data to Identify Factors Related to the Selection of Freeway Ramp Design Speed

Abstract: This project is primarily focused on identifying geometric design variables associated with an NDS driver’s chosen speed on a freeway ramp. However, there are applications for the human factors/safety side of the team to consider driver behaviors such as pedal position, steering wheel position, or head position in the context of actual speed and design speed to see if there are actions drivers are likely to take when a vehicle is traveling at a speed that is substantially different from the design speed. A further step could look at these items in relation to a documented crash or event. This research would explore the SHRP2 NDS database for the potential to identify freeway entrance and exit ramps and drivers’ behavior while traveling those ramps. This is in advance of a future task on NCHRP Project 15-56, which is tasked with reviewing current practices for selecting design speed on freeway ramps and, if beneficial, recommending changes to those practices. The NCHRP project will consider whether our current practices produce ramp design speeds that are consistent with the operating speeds that drivers actually choose, and if not, what changes should be made. On NCHRP 15-56 we will need to identify a selection of freeway ramps as possible study sites at which to collect data. We will also need to collect speed data (and probably lane position data, among other variables) on those ramps to compare actual speeds with the design elements of the ramp that influence the selection of a design speed.

By exploring the features of the NDS dataset, we can a) consider a new tool for study site selection based on roadway characteristics and b) identify a potential new source of data that can either serve as a basis for analysis or serve as a comparison or validation of field data that we will collect through other methods.


Subasish Das
Associate Transportation Researcher, Roadway Safety

Other Team Members: Bradford K. Brimley, Ph.D., Traffic Engineer; Tomas Lindheimer, Ph.D., Associate Transportation Researcher; Ashesh Pant, M.S., Assistant Transportation Researcher
Project Title: Safety Impacts of Reduced Visibility in Inclement Weather


This research seeks to better understand the ramifications of inclement weather on safety from a perspective of visibility. Visibility conditions at the time of a crash are rarely documented at a high level of detail. While vision is a key component of how drivers acquire information, a direct relationship between quantified levels of visibility and safety (in terms of crashes) should be identified. One of the factors affecting visibility is inclement weather. According to the Federal Highway Administration (FHWA), inclement weather contributed to over 13% of injury crashes and over 10% of fatal crashes in 2013. The SHRP 2 data collected in a natural environment provide a distinct opportunity to explore the safety effects of reduced visibility. The Naturalistic Driving Study (NDS) data and Roadway Information Database (RID) contain an unprecedented amount of information including kinematic measures, location with a Global Positioning System (GPS), computer vision lane-tracking, radar, video data, and detailed roadway data of the six study states. Data collected from the National Oceanic and Atmospheric Administration (NOAA) maintained airport weather stations that record visibility scores in real-time can be linked with SHRP 2 data—both data involving crashes or near-crash events and driver behavior data. Combined, this information can be used to investigate the safety effects of reduced visibility in terms of specific safety events and safety surrogate measures. This information can help practitioners more effectively design for visibility concerns and inclement weather.



The ATLAS Center is a collaboration between the University of Michigan (U-M) Transportation Research Institute (UMTRI) and Texas A&M Transportation Institute