Human Factors and Driver Compliance at Unconventional Intersections
Several types of
unconventional signalized intersections and interchanges have been in use or
have recently emerged as effective solutions to ever growing urban
congestion. These intersections and interchanges are innovatively created
to provide the higher operational efficiency than conventional designs would be
able to achieve. To name a few, unconventional signalized intersections
include: Median U-Turn (also called Michigan Left), Bowtie, Superstreet,
Jug-Handle, Quadrant Left, Continuous Flow, and Continuous Green
T–Intersection. Two types of emerging interchanges are Displaced Left Turn
Interchange (DLTI) and Diverging Diamond Interchange (DDI). Field studies
have demonstrated great success of such intersection and interchange designs
(e.g. 1), and some design guidance for these intersections and interchanges is
available in a Federal Highway Administration (FHWA) report (2).
The current practice
for analyzing the performance of such intersections and interchanges is
primarily micro-simulation. Research on the safety and operations
benefits of unconventional intersections is emerging, but limited information
is available to assess driver compliance with these designs (e.g. determine
types and frequency of illegal or unsafe movements by all road users- including
bicycles and pedestrians). This research is needed to assist
practitioners and researchers in improving these unconventional designs to
provide expected safety and operational benefits. It is expected this
research will provide guidance to improve typical unconventional intersection
designs including, but not limited to, an improved geometric layout and
enhanced use of traffic control devices, and these results may be included in
future national reference material such as the American Association of State Highway and Transportation Officials (AASHTO) Green Book, Manual on Uniform Traffic Control Devices (UTCD), and Highway Capacity Manual (HCM).
In addition to driver
compliance, other human factors that are barriers to implementation may also be
evaluated such as public and political misconceptions of such alternative
The objectives of this research are: (1) to evaluate installed unconventional intersections (including, but not limited to DDI, CFI, and dual-lane roundabouts) to determine motorist compliance with the design and traffic control devices; (2) to evaluate compliance of pedestrians, bicyclists, or other modes; and (3) to improve unconventional intersection design guidance. This research is expected to determine compliance with such designs by evaluating illegal and/or unsafe movements such as wrong-way, failure to yield, stopping at a yield sign, failure to stay in lane, etc. Countermeasures will be developed to improve user compliance with these designs.
The quantity of unconventional intersections and interchanges being constructed is exponentially increasing in the United States as a result of safety and operational research. This proposal should further enhance this research by evaluating how road users react to these designs, and proposes countermeasures to increase user compliance hence facilitating expected safety and operational benefits. This research and resulting guidelines are needed as soon as possible to provide practitioners better information to enhance designs and best serve the traveling public. Implementation by State and local DOTs could be immediate once guidelines are provided.
and MODOT (2011). Diverging Diamond Interchange Performance Evaluation (I-44
& Route 13). Jefferson City, MO.
(2010). Alternative Intersections/Interchanges: Informational Report
(AIIR). McLean, VA: USDOT. FHWA-HRT-09-060.
Missouri’s Experience with a Diverging Diamond Interchange - Lessons Learned.
Jefferson City, MO: OR 10 - 021.
The major tasks of this research include, but are not limited to the following:
· Conduct a comprehensive literature review on practices and
methodologies for analyzing unconventional intersections and
· Conduct an agency survey to determine types and presence of unconventional intersections,
· Conduct field studies to determine types and frequency of user non-compliance with these designs,
· Develop and evaluate countermeasures to improve motorist and non-motorist compliance at unconventional intersections,
· Produce recommended designs and documents that can be incorporated
into national references that propose to improve user compliance with
unconventional intersections, and to help dispel any public misconceptions of these designs.
Implementation by State and local DOTs could be immediate once guidelines are provided.
The quantity of unconventional intersections and interchanges being constructed is exponentially increasing in the United States as a result of safety and operational research.
|Sponsoring Committee:||AKD10, Performance Effects on Geometric Design
|Research Period:||24 - 36 months|
|Source Info:||Developed and submitted (September 2012) by Michael P. Reese and James H. Dunlop, North Carolina DOT.|
|Index Terms:||Signalized intersections, Manual on Uniform Traffic Control Devices, Highway capacity, Highway Capacity Manual, Left turn lanes, Diamond interchanges, Traffic flow, Microsimulation, Geometric design, Driver performance, |
Operations and Traffic Management
Safety and Human Factors