Security Region: An Intelligent Approach to Transportation Networks

This paper proposes a security region of transportation networks, which is defined as the set of flow states (operating points) satisfying the
$N-1$
security in transportation networks. The boundary of the set is closed, inside all the operating points are
$N-1$
secure; oppositely, outside all the operating points are insecure. First,
$N-1$
security of the transportation networks is defined, which means that when a road is blocked, vehicles on other roads within the networks can also reach their destination through different paths without being trapped on the road. Then, the security region of transportation networks is modeled. The algorithm of a boundary calculation is studied and the boundary equations of security distances are proposed. Finally, the proposed security of the transportation networks is presented in different examples. This paper demonstrates the following: 1) the security region can be accurately predicted by the simulation of
$N-1$
; 2) the boundary distance can show the necessary degree of security; 3) security can be improved by a preventive control scheme. The simulation on TransCAD is used to verify the correctness of the results.