Truck lane restriction
Truck lane restriction within transportation traffic engineering, is a factor impacting freeway truck lanes and traffic congestion. In traffic flow theory, intuitively, slow vehicles (e.g. trucks) will cause queues behind them, but how it relates to the kinematic wave theory was not revealed until Newell. Leclercq "et al" did a complete review of Newell's theory. In addition to the simulation models developed by Laval and Daganzo on the basis of numerical solution methods for Newell's theory to capture the impacts of slow vehicle, Laval also mathematically derived the analytical capacity formulas for bottlenecks caused by  single-type of trucks for multi-lane freeway segments. Analytical Solution of the Single-type Truck Problem. Laval's solution could be summarized as follows: Assuming a one-lane freeway segment obeying the triangular fundamental diagram defined in the figure to the right with free-flow speed "u", wave velocity "w" and jam density "k". Only one truck type is considered. In this scenario, the normalized capacity "I" of the freeway segment is given as： formula_1 where "r" is the time-mean proportion of trucks in the traffic stream,"C = uwnk/(w+u)"is the capacity of the freeway lane without trucks and  H is the expected value of headway between two consecutive trucks at the location where trucks begin to slow down It can be shown that, by approximating truck arrivals with Poisson processes, the probability density function (PDF) of "H" is the equation below, in which "τ" is defined as the clearance time of the queue induced by the slow-moving truck, "λ"="rC", "λ"="rU" and "τ"="L"("w"+"v")/"wv". Note that "λ" and "λ" refer to the mean truck arrival rate at traffic state "C" or "U", respectively. In particular, traffic state D, which corresponds to the downstream of the moving bottleneck, is assumed  to be equal to the capacity of the unblocked lanes. formula_2 According to Newell's moving bottleneck theory, we have: formula_3 Given all the above information, we can conclude that the average truck headway H is "H=(1-e)/(λ)+(e)/(λ)" And the above equation gives us all the necessary information to solve the normalized capacity "I".