01046211

Component

https://doi.org/10.3141/2023-01

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

AASHTO’s "Policy on Geometric Design of Highways and Streets" (Green Book) notes that acceleration and deceleration lengths should be adjusted on graded ramps. Factors are available in the 2004 Green Book to adjust acceleration lane and deceleration lane lengths for grades of 3% to 6%. The source of the adjustment factors was provided in the 1954 "Policies on Geometric Highway Design," in which they first appeared as being based on applying “principles of mechanics to rates of speed change for level grades.” Reviews of this and other documents did not reveal a procedure for determining adjustment factors. A potential source for an adjustment factor for entrance terminals is the calculation of the distance needed to accelerate from one speed to another on different grades by means of vehicle performance equations available in the literature. Potential acceleration length adjustment factors were developed and presented in this paper. The 2004 Green Book provides equations to calculate stopping sight distances for different grades. This methodology was applied to the equations used to calculate deceleration lengths so as to determine deceleration lengths for different grades. The ratio of the deceleration length on a grade to the deceleration length on a level surface formed the basis for adjustment factors for deceleration. Actual performance of vehicles on grades and on a level surface should be measured and compared with the suggested adjustment factors to determine the accuracy of those factors.

01088318

English

pp 1-9

2007

Transportation Research Record: Journal of the Transportation Research Board

9780309104500

Print

Figures (9) ; References (13) ; Tables (6)

Acceleration lanes; Adjustment factors; Deceleration lanes; Equations; Geometric design; Highway grades; Length; Off ramps; On ramps; Stopping sight distance

AASHTO Green Book

Design; Highways; I20: Design and Planning of Transport Infrastructure

TRIS, TRB, ATRI

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 Updates to 2004 Green Book's Acceleration Lengths for Entrance 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