Calculates traffic speed-density-flow relationships using the Greenshields linear model: u = u_f(1 − k/k_j), and maximum flow at k = k_j/2. Greenshields model: maximum flow q_max = u_f × k_j/4 — more realistic models (Greenberg, Underwood) better capture the speed drop in congested conditions.
Inputs
U F Kmh
Rate of movement. 1 m/s = 3.6 km/h = 2.237 mph.
Kj Veh Km
Mass per unit volume (kg/m³). Water: 1,000. Air: 1.225. Steel: 7,850. Affects buoyancy, flow, and structural loads.
K Veh Km
Mass per unit volume (kg/m³). Water: 1,000. Air: 1.225. Steel: 7,850. Affects buoyancy, flow, and structural loads.
Results
space mean speed u (km/h)
The computed rate of movement or processing.
flow rate q (veh/h)
Flow rate Q — the volume of fluid passing a point per unit time.
capacity flow qmax (veh/h)
Reference formula or conversion factor shown for context.
capacity density k_cap (veh/km)
Sample size or count used in the calculation.
u = uf·(1 − k/kj) | q = k·u
Reference formula or conversion factor shown for context.
LOS
LOS (length of stay) -- the number of days from admission to discharge. A key hospital efficiency metric.