Outline of Building the Traffic Simulation Model

Define the Problem and Model Objective

Prototype Model Objective:

Be able to demonstrate the feasibility of modeling traffic flow on the HOV lanes.

1)Produce an accurate representation of the current traffic flow.

2)Show the effect of short-term lane closure.

3)Show the effect of Weather, Rubber Necking or Speed Trap.

Define the Information that the model must provide:

1)The average-travel time.

2)Number of vehicles in a period time given.

3)The statistic on each segment.

4)The visual color-coded segment.

The System to be studied

1) HOV Lanes:

There are 2 separate simulation models: I-64 East and I-64 West

a) I-64 East

Entrants: I-564 and I-64 East

Exits: I-264/Newtown Rd., Rt-44 and I-64 East/Indian River Rd.

Length: 8 miles = 63,360 in.* 8 = 506,880 inches

East

b) I-64 West

Entrants: Rt-44, I-64 West/Indian River Rd. and I-64 West/North Hampton Blvd.

Exits: I-564 and I-64 West

Length: 8 miles = 63,360 in.* 8 = 506,880 inches

West

2) Parameters for the Model

a)Vehicle size: Average Passenger vehicles (195.97 inches = 196 inches)

b)Segment size:

c)Number of Lanes: 2

d)Speed:

e)Random number generator

f)Input data with appropriate distribution:

g)Exit data with appropriate distribution:

Develop the Model

This model is macroscopic simulation model.

1)Input:

a)Speed

b)Number of vehicles entering at each entrance according to the appropriate distribution.

c)Percentage of exiting vehicles using each exit.

2)Output:

a)The average-travel time (Speed / Delay).

b) Number of vehicles in a given period time (Volume).

c)The statistic on each segment (Percent Capacity).

d)The visual color-coded segment.

3)Flow of data within the model:

a)Input of the first segment by appropriate distribution for each entrance ramp.

b)Each succeeding segment after the first segment would get its input from the previous segment’s output.

c)Last segment output to exit ramp by appropriate distribution.

4)Functions and Processes of the model components:

Change the traffic flow through the segment based upon computed percentage of capacity.

5)The Calibration requirement and form:

a)Scalars: Vehicle size, Segment size.

b)Statistical distribution: Entrance Ramp, Exit ramp.

6)Develop abstraction of each major system component, their activities and interaction:

a)Capacity calculation equals Segment size divided the vehicle size plus following distance.

b)The Output at each Segment is the Input for the next Segment.

c)As the percentage of capacity increases the flow rate decreases in according to the Highway Capacity Manual (HCM)

d)Flow rate out of a segment decreases when there is a blocking event occurred within a segment.

e)After blocking event is cleared the flow rate will slowly increase.

7)Logical structure:( Depend on the Simulation language being used)

8)Select user interface and Presentation format of the result:

a)Color code segment of highway according to the percentage capacity.

b)Graphs of output data to show the travel time, volume, and percentage capacity over a specific period of time.

Calibrate the Model

1)Collect / Acquire data to calibrate the model:

2)Introduce the data into the model

Model Verification

1)Establish that the software executes in accord with the design specification.

2)Perform verification at the model component level

Model Validation

1)Collect, reduce, organize data for purpose of validation

2)Establish that the model describes the real system at an accepted level of accuracy over the entire domain of operation; apply rigorous statistical testing methods.

Outline of Building the Traffic Simulation Model