42 2011-2 Mathematical theories - Trafego

Questão 42

Mathematical theories

Some traffic engineers have attempted to apply the rules of fluid dynamics to traffic flow, likening it to the flow of a fluid in a pipe. Congestion simulations and real-time observations have shown that in heavy but free flowing traffic, jams can arise spontaneously, triggered by minor events (“butterfly effects”), such as an abrupt steering maneuver by a single motorist. Traffic scientists liken such a situation to the sudden freezing of supercooled fluid. However, unlike a fluid, traffic flow is often affected by signals or other events at junctions that periodically affect the smooth flow of traffic. Alternative mathematical theories exist, such as Boris Kerner’s three phase traffic theory.
Because of the poor correlation of theoretical models to actual observed traffic flows, transportation planners and highway engineers attempt to forecast traffic flow using empirical models. Their working traffic models typically use a combination of macro-, micro- and mesoscopic features, and may add matrix entropy effects, by “platooning” groups of vehicles and by randomising the flow patterns within individual segments of the network.

( http://www.time.com/time/world/article/0,8599,1733872,00.html. Acesso em 20.12.2008.)

De acordo com o texto,
(A) há modelos operacionais de tráfego que medem, pela Internet, o fluxo de trânsito atual.
(B) uma manobra abrupta feita por um motorista pode desencadear congestionamento de trânsito.
(C) alguns engenheiros de tráfego comparam a fluidez do tráfego com a de um fluido num cachimbo.
(D) os modelos operacionais de tráfego estão reduzindo o número de veículos nas principais rodovias.
(E) engenheiros ferroviários tentam prever congestionamentos de trânsito usando modelos empíricos.