The Effects of Detector Spacing on Traffic Forecasting Performance Using Neural Networks

An investigation was made as to how short-term traffic forecasting on motorways and other trunk roads is related to the density of detectors. Forecasting performances with respect to different detector spaces have been investigated with both simulated data and real data. Pruning techniques to the input variables used for neural networks were applied to the simulated data. The real data were collected from the M25 motorway and included flow, speed, and occupancy. With the data used in our study, the forecasting performances decrease with the increase of detector spaces. However, by taking the assumed costs of detector infrastructure into account, it may be concluded from this study that increasing coverage to a spacing of 500 m gives little extra benefit and may actually be counter productive in certain circumstances. It was concluded that, on the basis of current evidence, a detector spacing of between 1 and 1.5 km might be optimal.     

Real-Time Flood Forecasting Using Neural Networks

Real-time forecasting of stream flows during storms provides an essential input to operational flood management. This work is usually very complex owing to the uncertain and unpredictable nature of the underlying phenomena. The technique of neural networks therefore was applied to model it. Forecasting of flood values during storms with a lead time of one and more hours was made using a selected sequence of past flood values observed at a specific location. Training of the network was done with the help of three alternative methods, viz., error backpropagation, conjugate gradient, and cascade correlation. Resulting flood forecasts were found to be satisfactory—especially when warning time was the least.     

城市地下空间利用与地下交通规划

越来越拥挤的城市市内环境,使人们的生活空间越来越狭小,人们向地下要空间的愿望也越来越强烈。作为对人类社会影响最大的交通问题,如何在地下得到最优化的发展,如何规划,更好的为人民服务,是关注的焦点。     

城市地下道路交通安全评价与优化设计研究

为在城市地下道路设计阶段开展交通评价,通过优化设计提高城市地下道路的交通安全水平,在考虑城市地下道路特征、交通安全影响因素等基础上,结合专家意见征询与打分,从几何线形与行车视距、出入洞口、分合流与地下互通、路面与内部环境以及交通安全设施等五方面建立适合城市地下道路设计阶段的安全评价。其成果应用于苏州星港街地下道路设计之中,结果表明在城市地下道路设计阶段根据安全评价对设计方案进行系统的安全检查,能够及时发现潜在的安全隐患,通过优化设计加以改善。