01046209

Component

https://doi.org/10.3141/2023-14

http://scholar.google.com...rman&publication_year=2007

AASHTO’s "Policy on Geometric Design of Highways and Streets" (Green Book) notes that drivers entering a highway from a turning roadway accelerate until the desired highway speed is reached. Because the change in speed is usually substantial, provision is made for acceleration to be accomplished on an auxiliary lane, called an acceleration lane, to minimize interference with through traffic and to reduce crash potential. The 2004 Green Book contains acceleration lane lengths. The procedure identified to reproduce these values assumed running speed for the limited-access highway and the ramp along with acceleration rates from 1930s studies. Potential acceleration length values were then calculated by (a) updating the assumptions within the identified procedure and (b) using spreadsheets that can generate second-to-second acceleration. Findings from recent studies were compared with the existing Green Book values and the calculated suggested acceleration lengths. The suggested lengths determined in this paper, which are based on more realistic speed assumptions, more current acceleration lengths, and findings from recent research, are longer than the values in the Green Book. The paper recommends that additional research be done on acceleration lengths to determine whether the Green Book values should be increased.

01088318

English

pp 130-139

2007

Transportation Research Record: Journal of the Transportation Research Board

9780309104500

Print

Figures (7) ; References (26) ; Tables (6)

Acceleration (Mechanics); Acceleration lanes; Geometric design; Highway design; Length; On ramps; Research; Traffic speed

AASHTO Green Book

Updates

Design; Highways; Operations and Traffic Management; I20: Design and Planning of Transport Infrastructure; I73: Traffic Control

TRIS, TRB

Feb 8 2007 4:38PM

• Comparison of Two Unconventional Intersection Schemes: Crossover Displaced Left-Turn and Upstream Signalized Crossover Intersections
• Decision Support System for Predicting Benefits of Left-Turn Lanes at Unsignalized Intersections
• Determination of Storage Lengths of Left-Turn Lanes at Signalized Intersections
• Development of Accident Modification Factors for Rural Frontage Road Segments in Texas
• Lengths of Turn Lanes on Intersection Approaches: Three-Branch Fork Lanes—Left-Turn, Through, and Right-Turn Lanes
• Observed Distribution Patterns of On-Ramp Merge Lengths on Urban Freeways
• Operational and Safety Effects of Right-Turn Deceleration Lanes on Urban and Suburban Arterials
• Parameters for Evaluation of Speed Differential: Contribution Using Driving Simulator
• Placement Design of Ramp Control Signals
• Potential Changes to 2004 Green Book's Adjustment Factors for Entrance and Exit Terminals
• Relationship of Lane Width to Safety on Urban and Suburban Arterials
• Seemingly Unrelated Regression Model of Car Speeds and Speed Deviations in Freeway Work Zones
• Urban Freeway On-Ramps: Invasive Influences on Main-Line Operations