跨运营公路的桥梁上部现浇箱梁施工排架的设计

对于跨运营公路桥梁的施工,在保证车辆通行的条件下完成现浇箱梁,必须进行桥下的排架的设计,通过计算,使其强度和稳定性及应力验算得到验证。     

Excess commuting and modal choice

This paper reports results from research conducted to analyse the extent of excess commuting in Dublin, Ireland. The research differs from similar studies on excess commuting in two ways. First, a disaggregate modal choice analysis of excess commuting is undertaken for two time periods – 1991 and 2001. Second, sensitivity analysis is undertaken to explore the impact of changes in the density of the transport network for users of public and private transport. The results suggest that excess commuting is considerably greater for users of private transport implying the greater inefficiency of commuting associated with that mode. By way of contrast, capacity utilisation measures suggest the opposite indicating the difficulty of using these measures for policy-making. The results suggest also that the greater inter-mixing of jobs–housing functions has facilitated reductions in actual commuting costs as well as increasing the range of available trip possibilities over the study period. In terms of the sensitivity analysis, the results suggest that public transport users could achieve dramatic savings on their commute if the density of that network was increased considerably.     

Urban spatial location advantage: The dual of the transportation problem and its implications for land-use and transport planning

Numerous recent studies have investigated the relationship between the location of jobs and housing in urban areas and how this relates to urban commuting patterns. Few have utilised the dual of the transportation problem of linear programming (TPLP) to provide insights into these relationships Accordingly, this analysis utilises the TPLP to determine dual variable values (shadow prices) for a study area in Dublin, Ireland. The approach determines the pattern of relative location advantage for the peak and off-peak travel periods and for public and private transport for 1991 and 2001. The results are set against the expected results for hypothetical urban structures. The results show that the pattern of relative location advantage has altered sharply over the study period for off-peak trip-making but has remained more or less the same for trip-making in the peak period. For the off-peak period, the pattern of relative location advantage has shifted from the central area to the periphery specifically for private transport trips; for public transport, the pattern has remained focused on the city centre. This indicates that private transport users can react more quickly to changes in the distribution of land-use activities than their public transport counterparts due to the relatively fixed nature of the latter mode. This implies that the public transport network needs to be reorganized to better reflect the revised pattern of trip-making specifically for the off-peak period. The results demonstrate the value of using the approach for providing information about the spatial organisation of land uses within cities and where future development may be targeted.