In this paper, we establish an exact expression of the dynamic traffic assignment (DTA) problem with simultaneous departure
time and route (SDR) choices in transportation networks with bottlenecks, where both link and path capacities are time-dependent.
Using this expression, closed form of dynamic user equilibrium solutions can be obtained in some special networks. Furthermore,
we investigate the DTA-SDR problem in the classical Braess’s network with closed form equilibrium solutions. The explicit
results show that an inappropriately added new link could deteriorate the existing network in terms of the increase of individual
and system travel costs. The mechanism of this new paradox is quite different from that of the previously discovered ones,
and it is the first paradox caused by the simultaneous departure time/route competitions among individuals. 相似文献
This study investigated several ground collapses in sandy cobble strata induced by shield tunneling in two intervals of Lanzhou Metro Line 1 and proposed corresponding control measures. Ground collapses were classified into three types (A, B, and C). The distribution of low-compactness zones was the primary cause of the collapses that occurred after steady excavation (A-type), indicating that advanced grouting should be conducted beneath these zones. The grouting area should be a semi-circular ring in the transverse section, with a grouting ring height and thickness of 1.05 m and 0.51 m, respectively. A poor tunneling state caused by fluidity reduction in the cutter chamber was the main reason for collapses caused by restarting the shield after long-term shutdown (B-type). We suggest rotating the cutterhead every 12 h during long-term shutdown and supplementing the bentonite until the cutterhead torque falls below 3500 kN·m. Collapses caused by cutterhead blockage (C-type) were mainly due to encountering large boulders during tunneling. We suggest pulling the front shield back with hinge equipment when the cutterhead is blocked, with a backward distance greater than the penetration distance (35 mm) and a face pressure above the limit support pressure calculated using the method presented in this paper.