Better travel information can change traffic for the worse when many drivers act on the same message. A route that looks faster to an individual may become crowded after enough other travelers receive the identical signal.
Imperfect knowledge leaves the actual route split less extreme than the fully informed equilibrium shown at the start. A variable message sign encourages drivers to move toward the initially attractive route. The animation emphasizes the shifting flow while the system's total travel time rises; a final comparison makes the before-and-after result explicit. The lesson is not that travelers should be kept uninformed. Information changes behavior, and its network effect must be evaluated after drivers react, not only from the travel times displayed at the moment a sign is installed. Where the sign is placed and what it communicates can therefore matter as much as its accuracy.
Many commuters want to arrive at a similar time, but a bottleneck can admit only a limited number of vehicles per minute. If everyone departs near the preferred time, a long queue forms. If departures are spread out, the queue shrinks, but some people arrive early or late instead.
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Building an extra road sounds like an unambiguous improvement. Braess's paradox shows why that intuition can fail when drivers independently choose the route that seems fastest to them. A new link changes everyone's incentives, and the resulting route changes can overload roads that previously worked well.
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Drivers consider the time they personally spend on a road, but each additional driver may slow down many others. That difference between private and collective cost can make the route pattern chosen by individuals less efficient than the pattern that minimizes total travel time.
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