IFN Lab: Scenario Comparison - Reverse Link Direction

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By Kardi Teknomo, PhD

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Brief Description

In this IFN Virtual lab, you will learn how to solve traffic congestion by revesing link direcion one at a time until you reach the minimum irreducibility. A transport network must be strongly connected (irreducible). It means if you can go out of your home node to somewhere else node, you should able to go home, whatever node your home is. The minimum irreducibility capacity matrix is the minimum network where you cannot remove any link from it anymore. If you remove any single link from the minimum irreducibility matrix, your network become weakly connected or unconnected.

Given the capacity matrix \( \mathbf{C}_{0} \) of base scenario, you can modify it into the capacity matrix \( \mathbf{C}_{1} \) of alternative scenario. The modification can be done through of one the following:

In this page of IFN Virtual Lab, our focus is only on the policy of reversing link direction. Other policies such as adding or deleting lanes, adding link or removing link would be discussed in other IFN labs.

Example of reversing link include the temporary change of a certain road due to events such as demonstration, festival, religious events or repair of broken road.

Congestion matrix \( \mathbf{G} \) is computed by element-wise division between ideal flow matrix and the capacity matrix.

All the traffic performances such as travel time, delay, speed, density are computed based on link flow and congestion level. Thus, checking the maximum congestion level in one way to aggregate these traffic performances into a single index.

Learning Objectives

Prerequisite

Read: Graph Theory and Linear Algebra

Instruction

  1. Generate random irreducible capacity matrix by clicking . You can also modify it manually. The input capacity matrix must be a non-negative square matrix and irreducible. End each row separated by a semicolon. Separate each data in one row by comma or a space.
  2. Set the alternative scenario by modifying the base scenario. Select the feasible link and then click to add the feasible link to buffer. If there is no available feasible link, it means your alternative network scenario has reached the minimum irreducible.
  3. Click the arrow to create or update the Alternative scenario based on the base capacity matrix and modofication buffer.
  4. Set base-scenario congestion level and click to run the scenario comparison to compare the base scenario with the alternative scenario.
  5. Click on Find Scenarios button to generate the list all of the possible alternative scenarios of one link removal from your base capacity. Click on the header of the generated table to sort based on max congestion.

Experiment and Discussion

Lab Tool: Scenario Reverse Link Direction


Base Capacity




Pattern of Base Scenario
















Alternative Capacity




Pattern of Alternative Scenario

Base Capacity Network

IFN Lab: Scenario Comparison - Remove Link

Index