PCDN is facing serious congestion problem, due to the competition of port traffic and urban traffic flow on limited resource.
For each node, interchange construction decisions mean whether to change the intersection in PCDN to an interchange or not.
As described in the previous section, this paper focuses on the best construction time for each node in PCDN. To solve the network-level multistage decision problem, PCDN is denoted as G(N, A), where N represents the node set and A is the arc set.
The total cost at each year t, including all the construction cost [mathematical expression not reproducible] of retrofit nodes and delay cost [mathematical expression not reproducible] of PCDN, is hard to be formulated due to the real-time dynamic changed traffic volume.
The vehicle routing problem (VRP) for the traffic in PCDN needs to be solved, so that the traffic volume for each node and the delay cost can be calculated.
DP Model for PCDN. Interchange construction decisions are made by local governments to minimize the whole cost during a lifetime period.
Then, the multistage DP model for PCDN is formulated as follows:
[mathematical expression not reproducible] is the delay cost due to the traffic congestion for PCDN, which is influenced by the growth of fuel consumption and labor cost which consists of wages for truck drivers, as shown in
(1) Forecast of Traffic Generative Volume in PCDN. The traffic volume in PCDN includes two parts: freight traffic volume and passenger traffic volume.
Besides, there are several logistic zones in PCDN, which will cause freight traffic for the network.
The destination nodes of the freight traffic for PCDN are few and clear, such as the harbor highway junction.
The traffic volume in PCDN and trip distribution forecast work as the inputs of the TransCAD model.