Unformatted text preview: ver, in stochastic models a probability distribution is associated with the
arrival of events and the service times. In traffic and in most queueing situations the
entities arrive to the system with a probabilistic inter-arrival time (IAT) distribution and
the service times (ST) also have a probabilistic distribution varying for each entity.
Furthermore the output variables of the queueing systems, length of the queue and the
delay time for the entities are also probabilistic measures. The behavior of queues,
number of entities waiting in the queue, and delay times cannot be solved with a straight
forward mathematical approach unless IAT and ST are very well behaved mathematical
distributions (e.g. Negative Exponential, Erlang, or Hyper-Poisson).
Monte Carlo Simulation, run for many thousand times, can provide reliable
answers, which are very specific and unique, for determining system countermeasures.
Other methods, like deterministic simulations whe re arrivals and service times occur at
periodic time intervals cannot accurately capture the behavior of such queueing systems. 3
1.1 Statement of the Problem
Construction work zones on heavily traveled highways can cause problems for the motorists. Construction work zones may cause travel time delays, bottlenecks, and even
accidents. Slowing and merging traffic is the main cause of the problems in construction
work zones. Better planning of construction work zones before the starting of construction projects would decrease the problems associated with the work zone. In
most of the construction work zones with high hourly traffic volumes, paved shoulders or
medians are used to avoid the reduction of lanes. If the queue lengths and the delay times
for the traffic in the construction work zone would be known in advance, then, the
decision of whether or not a paved shoulder or median should be utilized for the traffic
could be made with more accuracy. If no excessive queues and waiting times would be
forecasted the cost of providing the extra temporary paved lanes could be avoided and a
large amount of costs could be saved. A simulation approach could forecast the lengths of
queues and the extent of delay times and alternative construction work zone solutions
could be explored without affecting the motoring public. Simulation has the potential to
help identify the outcomes of various configurations for construction work zone projects
without actually affecting the motoring public.
1.2 Objective of the Study
The objective of this study is to develop a traffic simulation model using ARENA simulation program to estimate the expected delays and queues using a probabilistic
inter-arrival time distribution in construction zones and to investigate the capabilities and 4
limitations of the ARENA simulation program for modeling traffic when the number of
lanes are reduced.
Another objective is to use a procedure to measure the traffic in a real world
situation and to process the time stamped traffic data in such a way that inter-arrival time
distributions can be used in the ARENA simulation model.
Furthermore, we also want to compare the results of the ARENA traffic
simulation model with the QuickZone Delay Estimation Program, which uses a
deterministic queueing modeling approach.
1.3 Scope of Work
The first step of this study is to find out the available construction work zone simulation programs available in the public domain and literature and find out what the
advantages and disadvantages of these simulation programs are.
The second step of this study is to conduct a literature review to find out traffic
behavior through the construction work zones.
The third step of this study is to develop a simulation model for the construction
work zone using the ARENA 7.01 simulation program by Rockwell Software.
The fourth step is to analyze measured traffic in a real world environment and
obtain probabilistic inter-arrival time distributions for different traffic volumes during a
day in order to validate the simulation program.
The fifth step is to compare the ARENA simulation program output with the
QuickZone delay estimation program output. 5
2.1 LITERATURE REVIEW
Work Zone Simulation Programs Evaluation Studies
QuickZone work zone delay estimation program, which was developed by The Federal Highway Administration (FHWA) in cooperation with Mitretek Systems ,
uses a deterministic inter-arrival time distribution for the estimation of the output
parameters. It uses a deterministic queueing model to simulate traffic going through
work zones to determine when there would be traffic backups. It is a tool intended for
highway engineers to determine how to set up a work zone to minimize traffic disruption.
QuickZone provides four primary outputs—a delay graph, a travel beha vior summary, an
amortized delay and construction cost graph, and a summary table. Detailed description
of the QuickZone delay estimation program is given in section 3.3.
In a study by Maze and Kamyab , a work zone simulation model was
View Full Document
- Spring '13
- Normal Distribution, ........., Cumulative distribution function, Driving Lane