1 Title: Modeling Crossing Behavior of Drivers and Pedestrians at Uncontrolled Intersections and Mid-block Crossings Objectives The goal of this study is to advance the state of the art in understanding traffic characteristics and modeling drivers’ and pedestrians’ behavior at uncontrolled intersections and mid-block crossings respectively. Based upon the existing research needs and the potential for utilizing data collected at various locations, the following research objectives are established to address goals of this research initiative: Research Objective 1 – Traffic Characterization To study the microscopic traffic characteristics at the functional area of unsignalized intersections, such as, vehicle category wise speeds on the major and minor legs, relative speed between the inner lane and outer lane of major road, conflict point study and vehicle trajectories study. Research Objective 2 – Drivers and Pedestrian Gap Acceptance Analysis Analyzing the driver and pedestrian behavior while crossing uncontrolled intersections and mid- block crossings respectively, which involves quantifying driver and pedestrian gap acceptance and gap rejection behavior, identification of the factors that affect drivers’ and pedestrians’ crossing behavior. Research Objective 3 – Dilemma Zone for Low Priority Streams Studying the dilemma of crossing vehicles and pedestrians. Finding location and length of the dilemma zone using probabilistic approach at uncontrolled intersections for vehicles and at uncontrolled mid-block crossings for pedestrians. Summary of previous work. Understanding traffic parameters such as speed, traffic composition, gap acceptance, and conflict points at microscopic level is necessary for developing performance evaluation models. These parameters also help to evaluate facilities with respect to safety. Many studies are found in the literature that focus on microscopic traffic characteristics at various transportation facilities in developed countries where traffic is disciplined. Very few studies are found that analyze traffic behavior at unsignalized intersections and mid-block crossings in India. The traffic behaves significantly different at unsignalized intersections and mid-block crossings in developing countries like India than at the intersections and crossings in developed countries which are controlled by stop and yield signs. The situation is more severe in India, because drivers and pedestrians do not follow the traffic rules strictly; major road drivers usually do not yield to minor
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Title: Modeling Crossing Behavior of Drivers and Pedestrians at
Uncontrolled Intersections and Mid-block Crossings
Objectives
The goal of this study is to advance the state of the art in understanding traffic characteristics and
modeling drivers’ and pedestrians’ behavior at uncontrolled intersections and mid-block crossings
respectively. Based upon the existing research needs and the potential for utilizing data collected
at various locations, the following research objectives are established to address goals of this
research initiative:
Research Objective 1 – Traffic Characterization
To study the microscopic traffic characteristics at the functional area of unsignalized intersections,
such as, vehicle category wise speeds on the major and minor legs, relative speed between the
inner lane and outer lane of major road, conflict point study and vehicle trajectories study.
Research Objective 2 – Drivers and Pedestrian Gap Acceptance Analysis
Analyzing the driver and pedestrian behavior while crossing uncontrolled intersections and mid-
block crossings respectively, which involves quantifying driver and pedestrian gap acceptance
and gap rejection behavior, identification of the factors that affect drivers’ and pedestrians’
crossing behavior.
Research Objective 3 – Dilemma Zone for Low Priority Streams
Studying the dilemma of crossing vehicles and pedestrians.
Finding location and length of the dilemma zone using probabilistic approach at uncontrolled
intersections for vehicles and at uncontrolled mid-block crossings for pedestrians.
Summary of previous work.
Understanding traffic parameters such as speed, traffic composition, gap acceptance, and conflict
points at microscopic level is necessary for developing performance evaluation models. These
parameters also help to evaluate facilities with respect to safety. Many studies are found in the
literature that focus on microscopic traffic characteristics at various transportation facilities in
developed countries where traffic is disciplined. Very few studies are found that analyze traffic
behavior at unsignalized intersections and mid-block crossings in India. The traffic behaves
significantly different at unsignalized intersections and mid-block crossings in developing
countries like India than at the intersections and crossings in developed countries which are
controlled by stop and yield signs. The situation is more severe in India, because drivers and
pedestrians do not follow the traffic rules strictly; major road drivers usually do not yield to minor
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road traffic even in the presence of yield sign. This condition further makes more challenging task
to analyze the traffic characteristics. The identified research gaps after doing through literature
review are outlined below.
Gap acceptance theory is limited to finding Capacity and LOS of the intersections and mid-
block crossings, only few studies have used gap acceptance theory for highway safety
considerations. Many gap acceptance studies are reported for homogenous traffic conditions
where lane discipline and priorities are respected. Modeling heterogeneous traffic conditions
is more challenging and complex task.
A majority of the research used time based gap/lag data for modeling driver and pedestrian
gap acceptance behavior. Spatial gap acceptance behavior of drivers and pedestrians at
uncontrolled intersections and mid-block crossings is not comprehensively studied.
Dilemma behavior of drivers at uncontrolled intersections and pedestrians at mid-block
crossings is not yet studied.
A few studies have examined the effect of night time on drivers’ behavior. For the most part,
data collected in these studies have not included speed, distance, and vehicle type of
conflicting vehicle. Thus, only a very few of these studies have been able to use and study
detailed traffic characteristics.
Methodology Overview
The methodology presented in this research rests on the assumption that driver and pedestrian
behavior can be modeled through a set of descriptive parameters, which can be calibrated from
filed data. The research presented in this study involves several tasks, as follows:
Selection of Intersections and Mid-block Crossings
Seven uncontrolled road intersections and two mid-block crossings with their approach segments
are identified for data collection. Each intersection having different vehicle composition is studied.
One intersection from town, two typical inner-city intersections, three intersections from outer
suburban road and one intersection on rural fast road are studied
Classification of Intersections
Selected intersections are classified/labeled as Type-I, Type-II, and Type-III intersections. Type-I
intersections are located at the city centre; Type-II intersections are located on outer link road
while Type-III intersections on rural national highway. Snapshots of three intersections, one in
main city, one in a suburb, and one in the outskirt of city are shown in Figure 1.
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Figure 1: Typical examples of type I, type II and type III intersections
Data Extraction
Except geometric data, all required data are extracted from the video recorded. For gap acceptance
and dilemma study, vehicle and pedestrian yielding behavior, accepted and rejected gaps, traffic
volume data are recorded at study sites and analyzed. The data extracted has total 1234 gap/lag
observations at three 4-legged intersections located on outer link road; 1469 and 1103 gap/lag
observations at one 3-legged intersection located on rural national highway for day and night
respectively, and 1107 gap/lag observations for pedestrians at two mid-block crossings.
Data Analysis
The data extracted is then analyzed for studying drivers and pedestrians gap acceptance and
understanding their dilemma at uncontrolled intersections and mid-block crossings respectively.
Gap acceptance study involves temporal as well as spatial gap analysis. For dilemma analysis,
variations in temporal and spatial gap acceptance behavior are analyzed to arrive at dilemma zone
boundary values.
Summary of Input Data
The preliminary analysis is done to understand different traffic parameters at uncontrolled
intersections. The preliminary analysis includes understanding of traffic composition, lane
preference, speed analysis, traffic conflict points, distribution of gaps, and vehicle trajectories.
Traffic Composition and Lane Preference
It is observed that Type I intersection is handling much higher traffic compared to others, and
Type II intersection traffic is higher than that of Type III. The traffic composition clearly shows
that very high proportions of two-wheelers are used in most cities of India. Similar observations
are reported in other studies (Sangole, 2011). The proportion of two-wheeler is highest at Type I
intersections. This is mainly because two-wheelers are preferred for shorter trips and in the areas
of high congestion.
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Table 1: 20-Minutes Volume Statistics in % with Type and Lane Choice
Inter. Type Lane 2W Car HMV Rickshaw Bicycle Total
Type I
Outer 40 30 5 60 95 42
Inner 60 70 95 40 5 58
Total % 71.89 10.51 1.71 13.28 2.61 2341
Type II
Outer 48 33 21 95 92 49
Inner 52 67 79 5 8 51
Total % 52.03 27.36 5.91 13.20 1.49 1674
Type III
Outer 3 30 40 100 0 21
Inner 97 70 60 0 0 79
Total % 48.17 29.74 19.27 2.83 0.00 955
Speed Analysis
Vehicle speeds are calculated at different distances by noting the vehicle crossing time at cross
grid lines along a vehicle path. The speed variations of vehicles along its path for a major approach
and a minor approach are depicted in Figure 2. The speed values at centre of intersection (0-0 m)
are much lower since vehicles have to slow down or stop because of crossing or merging of traffic
from other approaches and large number undisciplined pedestrian movements.
Figure 2: Speed variations for major road and minor road at type I intersection
Vehicle Conflict Points
Good understanding of how and where conflicts occur is required for the proper geometric design
and implementing efficient traffic control measures. Vehicle trajectories on the angular view from
video and the transferred trajectores on a plan are shown in Figure 3. One important observation
from the trajectory path is that the two-wheelers taking turns are not at the centre of the lane. As
far as possible the vehicles are on extreme right of an approach; this minimizes the crossing time
for a vehicle. Howerver, the standard 32 points conflict diagram is based on the assumption that
vehicle move at the center of a lane.
Distributions of Gaps and Observed Trajectory Data
The histograms for temporal and spatial gap along with the various distributions (Exponential,
Lognormal, Gamma and Weibull) fitted for all available gaps (accepted and rejected) are shown
0.0
10.0
20.0
30.0
40.0
50.0
Sp
eed
(k
m/h
r)
Distance (m)
Major Road (West Bound )
0.0
10.0
20.0
30.0
40.0
50.0
Sp
eed
(k
m/h
r)
Distance (m)
Minor Road (South Bound)
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in Figure 4. Based on Kolmogorov-Smirnov (K-S) test, it is observed that lognormal distribution