Assessment for CASA0002 – Urban Simulation
Deadline: 27th April 11am.
Word Limit – 3,000 words

The following assessment is designed to assess your understanding of the different urban modelling
methodologies introduced in the course, and their integration. The questions are based on the
coursework developed during the course and posted in Moodle. Using these codes you should be
able to work through the assessment. Carefully explain and illustrate your analysis with appropriate
diagrams. The assessment should not exceed 3000 words in total. (References, numerical tables and
data plots do not count towards the total number of words.)
The assessment will guide you to critically investigate the resilience of the London’s underground as
a network and its limitation. You will do this in two ways. In the first part, you will only take into
consideration the infrastructural network, where stations are connected through only one link,
regardless of the number of lines connecting the stations. In the second part, you will consider the
commuting flows, and discuss the impact of the analysis on the number of people moving from one
part of the city to another. Then, you will recompute the flows using spatial interaction models
according to different scenarios described below and discuss the vulnerability of the network under
these new scenarios.

Part 1: London’s underground resilience
Procedure: Make use of the coursework developed in class for the London’s underground, where the
underground is transferred into a network. Select 3 different centrality measures. For each measure,
remove at least 10 nodes following two different strategies: ‘sequential’ (recomputing the measure
after removal), ‘non-sequential’ without recomputing the measure after removal.
Analysis: Find 2 different measures to evaluate the impact of the node removal on the network and
find a way to report these results in the form of a plot instead of a table.
Discussion: critically assess your results following the comments given below.
Structure this part in 3 sections:
Section 1: Measures.
Introduce briefly the 3 centrality measures, and the 2 measures to evaluate the impact. Explain
whether these two measures to evaluate the impact are specific to the London underground or
generic? In doing so, explain if these would also be useful to evaluate the resilience of any other
network.
Section 2: Analysis.
Present the results of the analysis in the form of concise plots clearly labelled and compared the 2
different strategies (‘sequential’ vs ‘non-sequential’) considering the results for all the centrality
measures. Discuss whether the two different measures to evaluate the impact give the same results
and justify whether the findings were expected.
Section 3: Discussion.
Critically discuss which centrality measures are more relevant for this specific network, and the
limitations of the different measures selected for the evaluation of the node removal. Explain
whether different centrality measures would be expected for different networks, and comment on
the limitations of the approach to evaluate the “resilience” of London’s underground.

Part 2: Networks with flows and Spatial Interaction models.
For this section, you will be given a “symbolic” population and the number of jobs for the stations in
the underground. You will also be given the number of people that commute from one station to
another, through an OD matrix.
Structure this part as follows:
Section 1:
Select a measure from the previous analysis to measure the impact of node removal, and re-
compute the impact taking into consideration the number of people that need to travel from one
place to another, i.e. making use of the flows given to you. Discuss whether the centrality measures
that make the network more vulnerable are the same as in the previous section, and how your
measure to evaluate the impact of node removal needed to be adjusted.

Section 2:
Briefly introduce the spatial interaction models covered in the lectures using equations and defining
the terms, in particular explaining the role of the parameters. Using the information of population,
jobs and flows, select a spatial interaction model and calibrate the parameter beta. Make sure to
justify your selection of model.
Section 3:
Scenario A: assume that Canary Wharf has a 50% decrease in jobs after Brexit. Scenario B: assume
that there is a significant increase in the cost of transport. Using the calibrated parameter beta,
compute the new flows for scenario A. Then select 2 values for the parameter in the cost function
reflecting scenario B. Using plots, comment on the change in flows for the different stations given
the 3 different situations (scenario A, and scenario B with two selections of parameters). Which
scenario would have more impact for the redistribution of flows? Explain and justify your answers
using the results of the analysis.
Discussion section
Imagine you were a consultant for the TfL (Transport for London) asking you to evaluate the
resilience of the London’s underground. Explain how this type of analysis could be used, and its
limitations.









































































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