01091748

Component

This study compared the safety and operational effects of three driveway left-turn alternatives that were widely used in Florida and nationally, including direct left-turns from a driveway, right-turns followed by U-turns at a median opening and right-turns followed by U-turns at a signalized intersection. Data were collected at 40 selected roadway segments in central Florida. Traffic conflict technique was used for comparing the safety performance of different driveway left-turn alternatives. Delay and travel time effects associated with various driveway left-turn alternatives were estimated. The conflict data analysis results show that indirect left-turns are generally safer than direct left-turns from driveways. The delay and travel time comparison results show that indirect left-turn movement does not result in longer delay or travel time if U-turns are provided at a median opening in advance of downstream signalized intersection. This study also looked extensively at the capacity of U-turn movement at signalized intersections and median openings. U-turn adjustment factors were developed to account for the capacity reduction in the inside left-turn lane due to the presence of U-turning vehicles at signalized intersections. Critical gap and follow-up time for U-turn movement at median openings were estimated. With the estimated critical gap and follow-up time, Harders model was used for estimating the potential capacity of U-turn movement at median openings. The capacity estimation results provided a supplement for the current Highway Capacity Manual capacity estimation methods and can be directly used for estimating the capacity and level of service of U-turn movement at signalized intersections and median openings.

01091711

English

16p

2007

3rd Urban Street Symposium: Uptown, Downtown, or Small Town: Designing Urban Streets That Work

CD-ROM

Figures (4) ; References (25) ; Tables (5)

Driveways; Highway capacity; Highway operations; Highway safety; Highway traffic control; Left turns; Median openings; Right turns; Signalized intersections; Traffic delays; Travel time; U turns

Florida

Highways; Operations and Traffic Management; I73: Traffic Control

TRIS, TRB

Apr 1 2008 12:08PM

• A Generalized Model for Analyzing Operational Conditions at Intersections in Urban Areas
• A History of Pedestrian Signal Walking Speed Assumptions
• A Model of Potential Capacity of Right Turn Movement at Signalized Intersections Under Mixed Traffic Conditions
• Analysis of Multifunctional Traffic Environments
• Analyzing Raised Crosswalks Dimensions Influence on Speed Reduction in Urban Streets
• Applying Context Sensitive Techniques to Improve Design and Gain Stakeholder Support
• Benefits and Risks of Urban Roadside Landscape: Finding a Livable, Balanced Response
• Cross Section Width for Parallel Parking
• Design and Traffic Organization for Ultra-Wide Urban Street in China
• Designing Inside the Box - Strategies to Successfully Marry Smart Growth and Context-Sensitive Transportation Initiatives
• Designing Streets for Enhanced Transit Service: The Jerusalem Experience
• Driveway Design Practices, Issues, and Needs
• Estimating Running Time on Urban Street Segments
• Four-Lane to Three-Lane Conversions: An Update and a Case Study
• Geometric Design of Interchange in Urban City
• Improving Pedestrian Safety at Unsignalized Intersections
• Integrating Context Sensitive Solutions into University Transportation Education
• Involving the Public in Redesigning Urban Street Layouts in the UK
• Iowa's Experience with 2-Lane to 3-Lane Conversions
• Iowa's Experience with 4-Lane to 3-Lane Conversions
• Minnesota CSAH 42: A Case Study Illustrating Traffic Signal Removal as an Access Management Strategy
• Pedestrian Crossings Priority for Pedestrian Safety
• Recent Superstreet Implementation and Research
• Responding to the Challenges of Bicycle Crossings at Offset Intersections
• Retrofitting Urban Arterials into Complete Streets
• Review of Guidelines for Establishing School Speed Zones
• Safety Effect of the Skew Angle in Right Turn Maneuvers
• Separation Between Pedestrians and Bicyclists
• Shared-Use Streets – An Application of “Shared Space” to an American Small Town
• Speed: How Can We Get What We Want?
• St. Louis Great Streets Initiative
• Study on the Relationship of Intersection Design and Safety of Urban Unsignalized Intersection in China
• Study on the Safety Relationship between Left-turn Gap Acceptance and Waiting Time
• Sustainable Urban Street Design and Assessment
• Synthesis of the Median U-Turn Intersection Treatment, Safety, and Operational Benefits
• Traffic Calming in Slovenia
• Urban Street Reconstruction with Cultural Consideration-Research and Case Studies
• Yielding Behaviour and Interaction at Bicycle Crossings