Heterogeneous Lanes’ Saturation Flow Rates at Signalized Intersections

AbstractCorrect saturation flow rates are very important for the calculation of delays and level of service at intersections. However, the Highway Capacity Manual (HCM) procedure and the related studies assumed ideal conditions and cannot be applicable under mixed traffic circumstances. A traffic survey on 36 signalized intersections inside the Beijing's 5th Ring was conducted and a large number of experimental data with different lane types were statistically analyzed in this paper. Results show that the saturation headways approximately follow the normal distributions and the following base saturation flow rates are appropriate for Beijing intersections: 1380 passenger cars per hour per lane (pc/h/ln) of the right-turn lane, 1520 pc/h/ln of the left-turn lane, 1535 pc/h/ln of the through lane, 1457 pc/h/ln of the through-right lane and 1411 pc/h/ln of the through-left lane. These results have been used and verified in the real-time traffic information systems of Beijing Traffic Management Bureau

Vehicle Scheduling Optimization considering the Passenger Waiting Cost

In the operational planning process of public transport, the time a passenger spends on waiting is a very critical element for judging passenger service. Schedule synchronization is a useful strategy for reducing bus waiting time and improving service connectivity. This paper develops an extended vehicle scheduling model, taking into account the interests of passengers and operators in attaining optimization of timetable synchronization integrated with vehicle scheduling and considering the passenger waiting cost. Deficit functions at terminals are formulated. Deadheading (DH), shifting departure time (SDT), and network flow technique are used for vehicle scheduling with the consideration of passenger waiting times. An experimental study in Beijing is conducted and three important bus lines are selected as a regional bus network to demonstrate the methodology developed. Results show that both the fleet size of bus operators and the waiting cost of passengers are minimized. For example, the minimum fleet size can be reduced from 28 vehicles to 24 ones while the passenger times are less than 20 minutes in this multidepot network. Document type: Articl

Vehicle Scheduling Optimization considering the Passenger Waiting Cost

In the operational planning process of public transport, the time a passenger spends on waiting is a very critical element for judging passenger service. Schedule synchronization is a useful strategy for reducing bus waiting time and improving service connectivity. This paper develops an extended vehicle scheduling model, taking into account the interests of passengers and operators in attaining optimization of timetable synchronization integrated with vehicle scheduling and considering the passenger waiting cost. Deficit functions at terminals are formulated. Deadheading (DH), shifting departure time (SDT), and network flow technique are used for vehicle scheduling with the consideration of passenger waiting times. An experimental study in Beijing is conducted and three important bus lines are selected as a regional bus network to demonstrate the methodology developed. Results show that both the fleet size of bus operators and the waiting cost of passengers are minimized. For example, the minimum fleet size can be reduced from 28 vehicles to 24 ones while the passenger times are less than 20 minutes in this multidepot network

Piglets cloned from induced pluripotent stem cells

Embryonic stem (ES) cells are powerful tools for generating genetically modified animals that can assist in advancing our knowledge of mammalian physiology and disease. Pigs provide outstanding models of human genetic diseases due to the striking similarities to human anatomy, physiology and genetics, but progress with porcine genetic engineering has been hampered by the lack of germline-competent pig ES cells. To overcome this limitation, genetically modified pigs have been produced using genetically modified somatic cells and nuclear transfer (NT). Yet, somatic cells exhibit limited proliferative capacity and have an extremely low frequency of homologous recombination compared to ES cells. Hence, only a few knockout pig models have been reported thus far using standard gene-targeting approaches