Аннотация:Freeway work zone forms as a result of traffic crash or road rehabilitation. To ascertain theeffects of work zone with lane II completely blocked on vehicular flow on ring freewayswith a tunnel, a three-lane continuum model is put forward. The mandatory net lanechanging rate from lane II to lane I or III just upstream ofthe work zone with is describedby a random number model, with the random number being produced within a small rangearound a median based on golden section analysis. The net-changing rate between adjacentlanes is described using a lane-changing time on the basis of an assumption: the time ratioto relaxation time equals infinity when the absolute value of traffic densities between thetwo adjacent lanes is less than 1 veh/km, implying that the net-changing rate is zero;otherwise the time ratio is inversely proportional to vehicular spatial headway, which isequal to unity for traffic flow at saturation state, but to infinity for traffic flow completelyjammed. It is assumed that the freeway is a three lane ring with a total length of 100 km,and has a tunnel with a speed limit of 60 km/h and a length of 1.6 km located downstreamthe work zone with a length of 0.16 km. The free flow speeds on lanes I, II and III are 120,100 and 85 km/h respectively. For vehicular flows on the ring freeway with a tunnel,numerical simulations based on the three-lane continuum model are carried out with areliable numerical method of high accuracy. It is found that the vehicular flow has twothresholds of traffic jam formation, one depending upon the tunnel and the other uponthe work zone. The tunnel triggers a traffic jam when initial density normalized by jamdensity is equal to the first threshold 0.15, and the work zone originates another trafficjam when the normalized initial density equals the second threshold 0.19. The freewaytunnel plays a dominant role in the prediction of mean travel time as soon as the tunnelhas generated a traffic jam at the tunnel entrance. For vehicular flow at unsaturated state,the average speed through the tunnel is about 26.67 km/h. When the normalized initialdensity exceeds the second threshold 0.19, the mean travel time through every laneincreases with the initial density linearly. Vehicle fuel consumption can be estimated byinterpolation with the time averaged grid traffic speed and an assumed vehicle performance curve. It is found that the vehicle fuel consumption is lane number dependent, and distributes with initial density concavely, as well as has a value in the range of 6.5 to 8.3 l.
