01091656

Component

Superstreets are promising solutions for arterials. They have the potential to move more vehicles efficiently and safely through the same amount of pavement as conventional arterials, at-grade, with minimal disruptions to the surrounding environment and businesses. A superstreet works by redirecting left turn and through movements from side streets. Instead of allowing those to be made directly through a two-way median opening, as in conventional design, a superstreet sends those movements to a one-way median opening 800 feet or so downstream. Besides safety, capacity, and travel time, another profound change provided by a superstreet is in progression. With a superstreet, the signals that control one direction of the arterial can operate independently from the signals that control the other direction. This means that a superstreet can operate like a pair of one-way streets, and that perfect progression is possible at any speed with any signal spacing. This is an extraordinary capability; conventional arterials cannot approach this efficiency even with excruciating control of accesses and signal installations. Superstreets were developed in the early 1980s and a couple intersections have been in place in Maryland for years. The North Carolina Department of Transportation (NCDOT) has recently become a leader in superstreet development. The NCDOT built its first superstreet in a rural area as a safety countermeasure in 2000. The NCDOT opened its first signalized version in a suburban area in June 2006. The NCDOT has also adopted the superstreet as an appropriate design for important segments of its Strategic Highway Corridor system. The purpose of this paper is to provide an update on recent work on superstreets. The paper describes recent work on the capacity of a superstreet. The paper will then provide a summary of recent work on the progression capabilities of superstreets. The authors show that changing the progression speed does not change delay on a superstreet, thus freeing progression speed to be a design variable. Finally, the paper will review the performance of several recent superstreet installations in North Carolina. The first superstreets have generally performed as expected in delay and safety. However, there have been some surprises, such as much higher costs for traffic signal equipment. Agencies considering superstreets or looking for an alternative for a miserable stretch of arterial will benefit from learning about the experience with superstreets in North Carolina.

01091711

English

18p

2007

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

CD-ROM

Figures; Photos; References (9) ; Tables (2)

Arterial highways; Costs; Highway capacity; Highway safety; Highway traffic control; Progressive traffic signal control; Rural areas; Speed; Suburbs; Traffic delays; Traffic signal control systems; Traffic signal timing; Travel time

Progression speed; Superstreets

North Carolina

Finance; Highways; Operations and Traffic Management; I71: Traffic Theory; I73: Traffic Control

TRIS, TRB

Mar 31 2008 12:50PM

• 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
• 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
• Should Direct Left-turns from Driveways be Replaced by Right-turns Followed by U-turns? The Safety and Operational Comparison in Florida
• 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