Development of entrance ramp merging density model based on an urban expressway traffic condition
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Date
2007
Authors
Adnan, Muhammad Akram
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Abstract
Entrance ramp merging operation has significant impacts on expressway
traffic operations and ramp junction geometric design. To date no research work has
been conducted to assess the operational performance based on local entrance
ramp expressway traffic condition. The current entrance ramp operational analysis
methodology and models in the HCM 2000 are calibrated based on the United States
(US) highway and traffic conditions. The application of the HCM needs to be justified
for use in this country due to the fundamentally differences in driving habits, traffic
composition and design configuration. Proper application of the models is crucial in
order to ensure that the future designs of expressways are safe, efficient and
economical where the issues of under-design or over-design of expressway will not
occur. Also, the Malaysian guidelines and standard as in the Arahan Teknik Jalan:
Interchange Design 1987 is out of date, which is based on the US HCM 1985 and the
methodology approach and measure of effectiveness are totally different from the
current HCM 2000 edition. Therefore a well-established empirical study had been
implemented to calibrate entrance ramp merging models that are based on an urban
entrance ramp expressway traffic condition in Malaysia. Two models were
successfully developed in these studies that are needed in order to determine the
Level of Service at entrance ramp merge junction. The first model is for estimating
flow rates in lane 1 and 2 immediately upstream of the merge influence area and the
second model is for prediction of density in merge influence area at entrance ramp
junction. Sensitivity analysis had also been performed in order to measure how
sensitive each of the predictor parameters for the two models. The development of
the entrance ramp level of service estimation chart provides a valuable tool to be
used by practitioners. Several graphs were created based on the models developed.
Application example of using the chart had been demonstrated. As a result, traffic
engineer and highway planner can use the developed chart in order to evaluate the
existing entrance ramp expressway facilities Level of Service in an effective and
systematic manner.
Description
PhD
Keywords
science mathematics , entrance ramp , density model , urban expressway , traffic condition