Volume/Capacity Ratio (V/C)
Calculate the volume/capacity ratio (degree of saturation), X = V ÷ C, dividing the traffic volume V by the capacity C of the road or intersection. The dimensionless result measures the road's utilization: X near 0 indicates a free road; X = 1 means the road operating exactly at capacity; X > 1 indicates demand above capacity, with growing queues and congestion. The V/C ratio is the main indicator to classify the level of service (LOS A to F) and identify bottlenecks. Values above 0.85–0.90 already indicate near-saturation operation. Enter the volume and the capacity.
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Relação volume/capacidade (V/C)
A relação volume/capacidade (V/C), também chamada de grau de saturação (X), é o indicador mais usado para diagnosticar o desempenho de uma via ou interseção: X = V ÷ C, o volume de tráfego demandado dividido pela capacidade disponível. O resultado, adimensional, conta uma história imediata sobre o estado da via. X próximo de 0: via praticamente vazia, fluxo livre, velocidade máxima. X em torno de 0,5–0,7: tráfego estável, mas já perceptível, com alguma redução de velocidade e liberdade de manobra. X = 0,85–0,90: a via se aproxima da saturação — pequenos distúrbios (uma freada, uma conversão) começam a gerar ondas de congestionamento, e a operação fica instável. X = 1,0: a via opera exatamente na capacidade, o ponto de máxima vazão, mas também de máxima fragilidade — qualquer aumento de demanda ou perturbação a derruba. X > 1,0: a demanda excede a capacidade; forma-se uma fila que cresce continuamente enquanto durar a sobredemanda (o congestionamento não é um estado, é um processo acumulativo), e a via passa a operar em fluxo forçado, com velocidades baixíssimas. A relação V/C é a base para classificar o nível de serviço (LOS, numa escala de A a F, de fluxo livre a colapso) e para identificar gargalos numa rede — os pontos de maior V/C são onde investir. Informe o volume e a capacidade.
Related Tools
Saturation Flow
Calculate the saturation flow of a signalized approach, S = S₀ × N, multiplying the base saturation flow per lane S₀ (vehicles/h per lane, typically ~1800–1900) by the number of lanes N. The result, in vehicles/h, is the maximum rate of vehicles that can cross the stop line if the signal stayed green continuously and a queue existed — the queue discharge rate during green. It is a central parameter in signal design and intersection capacity, adjusted by lane width, grade, turning and parking factors. Enter the base saturation flow per lane and the number of lanes.
Average Headway
Calculate the average headway (time interval between successive vehicles), h = 3600 ÷ q, dividing 3600 seconds by the flow rate q (vehicles/h). The result, in seconds, is the average time between two consecutive vehicles passing a point. Headway is the inverse of flow: the higher the traffic volume, the shorter the intervals. It is a central concept of traffic flow theory, used in signal design, capacity analysis and car-following models. The smallest safe headway defines the maximum capacity of a lane. Enter the flow rate.
Equivalent Flow (PCE)
Calculate the equivalent flow in passenger car equivalents (PCE), q = Q_cars + Q_heavy × E, adding the car flow to the heavy-vehicle flow multiplied by the equivalence factor E (how many passenger cars each truck or bus equals in road occupancy — typically 1.5 to 3.0). The result, in PCE/h, converts a mixed traffic stream into an equivalent homogeneous one, allowing volumes to be compared and the capacity of roads with different traffic compositions to be computed. Heavy vehicles occupy more space and accelerate more slowly, especially on grades. Enter the car flow, the heavy-vehicle flow and the equivalence factor.
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