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CHAPTER 8
Pedestrian LOS Model
8.1 Model Development ticipant assigned to a specific video clip. The scores were on a
scale of A (best) through F (worst). For modeling purposes,
Two basic forms were considered for the pedestrian LOS the letter grades were converted to numerical scores: A=1,
for arterials model. The first was an aggregate model that used B=2, C=3, D=4, E=5, and F=6.
the outputs from existing segment and intersection LOS Before starting correlations analysis and modeling, we cre-
models to determine the arterial LOS. The other was an ated two data subsets from the overall dataset. The total
agglomerate model that considered the independent charac- dataset was sorted by city and LOS grade responses. A ran-
teristics of the roadway/walkway environment to calculate an dom sampling of 20% of the data representing each city and
arterial LOS for pedestrians directly. Both were preliminarily LOS grade response was taken from the overall dataset for
evaluated during model development. model validation. The balance of the data, 80% of the total
The aggregate model was chosen for refinement for several dataset, was used for model development.
reasons. The stepwise approach to an aggregate model is use- We used SPSS 14.0 to conduct Pearson correlation analysis
ful because it allows the practitioner to evaluate the effect of on the extensive array of geometric and operational variables.
improvements at individual intersections or along specific Subsequently, we selected the following relevant variables for
segments on the overall LOS of the facility. The aggregate additional testing:
model also retains all the terms found both intuitively and
mathematically validated to be significant to pedestrians walk- · Segment LOS--The pedestrian LOS for roadway segments
ing within an urban environment. The agglomerate models (see below).
form was tested during our preliminary models and did not · Intersection LOS--The pedestrian LOS for signalized
retain all the terms as significant. Consequently, we focused on intersections (see below).
the aggregate model in our model development efforts. · Midblock Crossing LOS--The LOS associated with mid-
We considered various functional techniques for model de- block crossings (see below).
velopment, including linear regression and ordered probit. We · Total Pedestrians--The total number of pedestrians
performed linear regression modeling because it is more intu- encountered in the video clip; a measure of pedestrian
itive than probit modeling in practice and non-modelers better space, which is an input to the existing pedestrian LOS
understand the sensitivity of the regression model. These rea- methodology in the HCM.
sons are particularly important in that these models are most · Conflicts per mile--The total conflicts per mile represent
frequently used: the development or analysis of specific design the motor vehicle conflicts resulting from motorists turn-
options or in the development of pedestrian facility community ing across the pedestrian facility at unsignalized locations.
master plans with presentations to interested citizens and pub- · Size of the city in which the data collection took place--
lic officials. To ensure the validity of the results of the linear re- The MSA population was used to represent the size of
gression modeling results, we evaluated the ordered probit each city.
model form as well. The results of both the linear regression and
ordered probit modeling efforts are described below. The panel asked that MSA be dropped from further con-
For both modeling efforts the dependent variable, sideration as a variable. Other variables were dropped from
Observed pedestrian LOS, was defined as the score that a par- further consideration because of their poor correlation with
