Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Optimised Traffic Flow at a Single Urban Crossrtoads: Dynamical Symmetry
  Breaking   We propose a stochastic model for the intersection of two urban streets. The
traffic state at the crossroads is controlled by a set of traffic lights, which
periodically switch to red and green with a total period of T. Vehicular
dynamics is simulated and total delay experienced by the traffic is evaluated
within a definite time interval. Minimizing the delay give rises to the optimum
signalization of traffic lights. It is shown that two different phases are
identified. In the light traffic phase, the green times should be distributed
to the streets on an equal basis. In the congested phase, minimizing the delay
enforces us to break the symmetry between the roads by allocating the majority
of green times to one of the roads. In contrast to our common sense, dividing
the green times on an equal basis, leads to unfairness to drivers.

8
The categories of this paper are: hep-ex
18
The categories of this paper are: econ
29
The categories of this paper are: funct-an
26
The categories of this paper are: bayes-an
20
The categories of this paper are: acc-phys
30
The categories of this paper are: q-alg
35
The categories of this paper are: mtrl-th
5
The categories of this paper are: gr-qc
2
The categories of this paper are: math
16
The categories of this paper are: stat
1
The categories of this paper are: cs
14
The categories of this paper are: math-ph
9
The categories of this paper are: nlin
6
The categories of this paper are: astro-ph
33
The categories of this paper are: plasm-ph
31
The categories of this paper are: ao-sci