01557910

Component

https://doi.org/10.3141/2483-13

Heavy-vehicle (HV) impact on freeway operations in the Highway Capacity Manual 2010 is evaluated on the basis of values for passenger car equivalents (PCE) for buses–trucks and recreational vehicles. These values were calibrated for relatively uncongested freeway conditions [Levels of Service (LOS) A through C] because inadequate field data on HV behavior under congested conditions were available; furthermore, field-collected headway information was based on the average headway for vehicles in a particular class, regardless of the type of vehicle that they were following. The goal of this paper was to collect and analyze freeway field data on HV headways with an emphasis on lower speeds typically associated with an LOS E (capacity) or F (forced-flow conditions). The effect that a leading vehicle has on headways was captured and analyzed for 10 leading–following vehicle pair types containing at least one passenger car (for example, buses followed by passenger cars). Headway statistics were analyzed for nine speed ranges (up to 20 mph, 20 to 25 mph, 25 to 30 mph, 30 to 35 mph, 35 to 40 mph, 40 to 45 mph, 45 to 50 mph, 50 to 55 mph, and over 55 mph) and 10 vehicle pair types. Values for PCEs were derived for each speed range on the basis of average headway for a specific vehicle pair type divided by the average headway between passenger cars. Leading and following vehicle classes and speeds were found to have a significant influence on headways and values for PCEs.

01587923

15-4650

English

pp 111–119

2015

Transportation Research Record: Journal of the Transportation Research Board

9780309369268

Print

Figures (6) ; References (26) ; Tables (5)

Car following; Freeway operations; Headways; Heavy vehicles; Highway capacity; Level of service; Passenger car equivalence; Traffic congestion; Traffic flow rate; Vehicle classification

Data and Information Technology; Highways; Operations and Traffic Management; Planning and Forecasting; I71: Traffic Theory

TRIS, TRB, ATRI

Dec 30 2014 1:32PM

• A German Approach to Freeway Facility Evaluation
• Average Delay at Unsignalized Intersections for Periods with Variable Traffic Demand
• Calibrating VISSIM for the German Highway Capacity Manual
• Effect of an Upstream Traffic Signal on the Capacity of a Downstream Two-Way Stop-Controlled Intersection
• Evaluation of Methodologies for Analyzing Freeway Ramp Weaving
• Generalized Effects of On-Street Parking Maneuvers on the Performance of Nearby Signalized Intersections
• Generating Scenarios of Freeway Reliability Analysis: Hybrid Approach
• Generic Speed–Flow Models for Basic Freeway Segments on General-Purpose and Managed Lanes in Undersaturated Flow Conditions
• Methodology to Compute Travel Time of a Roundabout Corridor
• On the Treatment of Trucks for Analysis of Freeway Capacity
• On the Treatment of Trucks in Roundabout Analyses
• Planning-Level Methodology for Freeway Facilities
• Relationship of Lane Width to Capacity for Urban Expressways
• Risk-Taking Behavior of Left-Turners in Gap Acceptance and Its Effects on Capacity Estimation at Signalized Intersections
• Updated Commercial Truck Speed Versus Distance–Grade Curves for the Highway Capacity Manual
• Vehicular Traffic Capacity at Unsignalized Crosswalks with Probabilistic Yielding Behavior