01552845

Component

https://doi.org/10.3141/2483-02

To increase the capacity of urban expressways in Shanghai, China, additional lanes were created during the past decade through reconstruction. Field measurements indicate that maximum lane width is 3.97 m and minimum width is only 2.73 m. To investigate the relationship between lane width and capacity for urban expressways, 3 months of traffic flow data were extracted and filtered from the system to manage inductive detectors on Shanghai’s urban expressways. Analysis of all 440 segments of expressways in Shanghai showed that only 60 sites could reach their capacity; the characteristics of these 60 sites were further analyzed statistically. An analysis of a variance, a regression analysis, and a t-test were used to explore the relationship between lane width and capacity. The research showed that lane width had no statistically significant effect on capacity. Two causes that might account for this finding are discussed further: (a) free-flow speeds are similar for different lane widths according to the findings of a t-test that found no statistically significant differences and (b) the critical speed when capacity is reached for a Shanghai expressway is very low, only 45 km/h. Thus, drivers can deal with a narrow lane width at such a low critical speed. This finding suggests that geometric design policies for capacity purposes should provide substantial flexibility for use of narrower lane widths on urban expressways with low speed limits, although those lane widths must be subject to safety considerations.

01587923

15-0465

English

pp 10–19

2015

Transportation Research Record: Journal of the Transportation Research Board

9780309369268

Print

Figures (4) ; References (11) ; Tables (9)

Expressways; Highway capacity; Speed; Traffic lanes; Urban highways; Width

Shanghai (China)

Highways; Operations and Traffic Management; Planning and Forecasting; I70: Traffic and Transport

TRIS, TRB, ATRI

Dec 30 2014 12:16PM

• 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
• Field-Derived Freeway Passenger Car Equivalents for Congested Conditions
• 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
• 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