Graphs and networks are a fundamental aspect of Civil Engineering Systems.

For example, ...

• Transportation engineers are concerned with the design and operation of rail, road, shipping, and air traffic networks.
• Hydrology engineers work with networks of waterways.
• Structural engineers work with networks of load bearing members (usually beams and columns).
• Architects create networks of spaces (rooms).

Motivating Example: Washington DC Metro System

The following figure is a simplified model of the Washington DC Metro System (most of the stations have been omitted):

Figure 1. Simplified view of the Washington DC Metro System

Passengers need to be familiar with the routes, schedule, and cost of using the metro. Typical questions include:

• When will the metro open? When will it close?
• How do I get from station A to station B?
• Will I have to change trains? Where?
• How long will it take to get there? And how must will it cost?
• I'm going to the Smithsonian -- what station should I get off?
• I'm at station A. When is the last train to station B?

The Smithsonian question is particularly interesting because: (1) it requires that a transportation model be linked to a geographic information systems (GIS) model, and (2) there really isn't a unique answer.

In its most rudimentary form, the Metro System can be modeled as a graph structure. Nodes in the graph correspond to train stations; the edges correspond to the tracks connecting stations. Graph theory is useful because it provides algorithms to answer questions about routes connecting stations A and B.

The adjacent code is a first-cut implementation at modeling this problem domain.

Question
How would you extend the basic node-edge graph structure to make the model more realistic.

REFERENCES

1. ....
2. Wicked Cool Java ...

Developed in October 2011 by Mark Austin
Department of Civil and Environmental Engineering, University of Maryland