Keywords

Human Factors, Express Lanes, Managed Lanes, Separation Width, Buffer Width, Delineators, Driving Simulator, and MUTCD

Abstract

Buffer separation with delineators is one of the commonly used separation treatments across US highways to distinguish managed lanes (ML) from general purpose lanes (GPLs). As MLs continue to be integrated into US highway system for improving traffic flow and reducing congestion, this separation method has become more popular due to its flexibility and cost efficiency over more robust physical separations. While past studies have explored the effectiveness and safety of buffer separations with delineators compared to other treatments, none have examined how specific changes within the buffer design—like separation width and delineator height—impact driver behavior. It is particularly important because there is a disparity among state specific applications of buffer separation designs. This study is the first to present an evaluation of the effect and noticeability of different separation widths (double vs single solid lines) and delineator heights (24-inch vs 28-inch, especially in curved sections) on driver behavior by investigating behavioral data from a driving simulator, visual attention data from an eye-tracking device, and participants’ subjective survey responses. The experiment was conducted at the Transportation Systems Lab of UCF and included 60 drivers evenly distributed across age and gender groups. Each participant drove through 16 scenarios that varied by traffic density, time of day, visibility, and separation design. Results showed that double solid lines were more noticeable than single solid lines across different conditions. Double solid lines were associated with higher deceleration, mean speed, lateral deviation, and longer fixation durations. Among delineator heights, the 28-inch delineators were more noticeable to drivers, whereas the 24-inch delineators led to larger lane deviation, more frequent steering adjustments, and tend to have longer fixation durations in ML curves. In combination, double solid lines with 24-inch delineators further resulted in reduced mean speed in the curved section.

Completion Date

2025

Semester

Summer

Committee Chair

Hatem Abou-Senna

Degree

Master of Science in Civil Engineering (M.S.C.E.)

College

College of Engineering and Computer Science

Department

Department of Civil, Environmental and Construction Engineering

Format

PDF

Identifier

DP0029506

Language

English

Document Type

Thesis

Campus Location

Orlando (Main) Campus

Download

Share

COinS