Effect of Bicycles on Capacity of Signalized Intersections

Abstract

Although much is known about the operation of signalized intersections, little or no empirical research has been conducted regarding the effect of bicycles on signalized intersection capacity. The purpose of this study was to accurately quantify the effects of bicycles on signalized intersection capacity through the videotaping of several intersections that had significant bicycle traffic. Through the videotaping of intersections in Davis, California, and Gainesville, Florida, a relationship was determined between bicycle volumes and the percent of the green phase during which bicycle traffic occupies a conflict zone between bicycles and right-turning motor vehicles. It was also determined that one can ascertain the total net occupancy due to pedestrians and bicycles by taking the overlapping effects between bicycles and pedestrians into account. Using this total occupancy due to bicycles and pedestrians, one can calculate a saturation flow adjustment factor ( fRph) that reflects the reduction in saturation flow, and ultimately lane group capacity, for lane groups containing vehicles making permissive right turns in the presence of bicycles and pedestrians. The proposed procedure yields lower saturation flows and capacities than the current Highway Capacity Manual (HCM) procedure. In other words, on the basis of empirical data, when combined with pedestrian effects, the impact of bicycles on the saturation flow of lane groups containing right-turning vehicles is probably more detrimental than previously believed, and the capacities of intersections with significant bicycle and pedestrian traffic may be overestimated by using the current HCM procedures.

Estimating cycleway capacity and bicycle equivalent unit for electric bicycles

“…The capacity for a single 1 to 1.2 m bicycle lane differs greatly across different studies, which may be due to differences with respect to calibration methods, bicycle facilities, characteristics of cyclists, and travel purposes. Majority of the estimated capacity results fall between 1300 and 2700 bicycles/h/m (Allen et al, 1998a(Allen et al, , 1998b.…”

“…One is the capacity under uninterrupted-flow conditions, which is the main research object of this paper. The other is the capacity under interrupted-flow conditions, especially the saturation flow rate or capacity of bicycles and the effect of bicycles on the motorized vehicle capacity at signalized intersections (Allen et al, 1998a(Allen et al, , 1998bRaksuntorn and Khan, 2003;Wang et al, 2011aWang et al, , 2011b.…”

A cellular automata (CA) model for motorized vehicle flows influenced by bicycles along the roadside

“…Many studies have examined scenarios at intersections. For example, Allen et al investigated the effects of bicycles on signalized intersection capacity by videotaping several intersections with significant bicycle traffic. Sayed et al demonstrated an automated safety diagnosis approach for evaluating vehicle–bicycle conflicts at an intersection using video analysis.…”

“…Many studies have examined scenarios at intersections. For example, Allen et al [1] investigated the effects of bicycles on signalized intersection capacity by videotaping several intersections with significant bicycle traffic. Sayed et al [2] demonstrated an automated safety Although existing studies have addressed the interactions of motorized vehicles and bicycles on road sections and some have proposed simulation models [12][13][14][15][16][17], they have not considered the deceleration process of the motorized vehicle before it passes the bicycle ahead.…”

Capacity of Bicycle Platoon Flow at Two-Phase Signalized Intersection: a Case Analysis of Xi’an City

“…Of course, such efforts often cause significant reduction in LOS and capacity performance of intersection-related locations [8,9]. A study by Allen et al [10] highlights the quantitative impacts of total occupancy due to bicycles and pedestrians in reducing saturation flow and ultimately lane group capacity through the videotaping of intersections in Davis and Gainesville, and they also argue that the impact of significant bicycle traffic on decreasing the capacity of signalized intersection may be overestimated according to the prevailing "Highway Capacity Manual" (HCM) approaches that would quantify a composite level of service of intersections under mixed flow environment [11][12][13]. Chen et al (2007) summarize the impact of trapped bicycles on the through vehicular traffic from four types: a. blockage by bicycles at the beginning of the green phase; b. influence of waiting bicyclists; c. influence of traversing bicyclists; and d. influence of trapped bicyclists in the intersection [14].…”