Abstract
Disturbance to the moving traffic, such as on-street parking and bus stop on carriageway normally called as side friction in the literature, is one of the major problems that impact the vehicular speed on urban arterials in developing countries like India. Regression model to study the mode-wise vehicular speeds using side friction and other influencing variables faces the problem of multicollinearity as there is a strong correlation between the independent variables which results in high R2 and high p values. Instead of dropping the highly correlated variables which is the conventional practice to deal with multicollinearity, we proposed an approach of taking a linear combination and ratio of independent variables. To test the applicability of the proposed approach, traffic data from five locations in Hyderabad and Vellore in India having a wide variety of geometric and traffic characteristics with one or more side frictions were collected and regression models were built. It was found that the proposed approach of taking linear combination and ratio worked very well as the models exhibited a high R2, low p values and low variance inflation factor. The regression models also forecast speeds with good and reasonable accuracy. For better understanding of the impact of side friction, the present study proposed an index called side friction index and it was found that the number of side friction elements and their impact are directly proportional. Also, the impact is not uniform across the different vehicle types. Though the present study focussed on side friction problem, the approach that we proposed in this paper to deal with multicollinearity can be applied in other fields as well.
Highlights
Introduction and BackgroundSide friction refers to activities such as on-street parking, roadside encroachment which can be seen on sides of carriageway or sometimes within the carriageway that normally results in loss of effective carriageway width and thereby causes disturbance to the normal traffic flow
The results of the study were presented in the same order of methodology, i.e., the results of t test are presented first followed by the regression model development and multicollinearity analysis
Old Neredmet road has four types of side friction elements such as bus stop, on-street parking, pedestrian movement, wrong movement and the impact is more which results in the lowest Side friction index (SFI) compared to other locations
Summary
Side friction refers to activities such as on-street parking, roadside encroachment which can be seen on sides of carriageway or sometimes within the carriageway that normally results in loss of effective carriageway width and thereby causes disturbance to the normal traffic flow Besides these static activities, dynamic events like stopping of buses on the carriageway, wrong-side driving and pedestrians walking on carriageway cause hindrance to the vehicular movement. Dynamic events like stopping of buses on the carriageway, wrong-side driving and pedestrians walking on carriageway cause hindrance to the vehicular movement All these side friction elements eventually result in speed reduction in vehicles, and thereby capacity and level of service (LOS) got reduced. The review of existing studies leads to the following gaps as explained below
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