Study of Preparation Specifications for 3-Dimensional Topographical Map Data for Road Design in Japan

3-dimensional CAD is known to be an effective and convenient method of designing roads. But road design in Japan makes little use of 3-dimensional CAD. This is due to the fact that Japanese topographical surveys provide 2- dimensional topographical map data, and height data have to be newly input at the road design phase. The reason for this phenomenon is that results of the survey phase and uses at the downstream phases are not linked. This study is intended to create a procedure for providing topographical map data including height data needed for 3-dimensional road design from the survey phase to the design phase. This paper reports on the achievements of the study of “3-dimensional topographical map data preparation specifications”. Considering the topographical survey work load, height data will be provided to the new regulations, is desirable to minimize. Therefore, these preparation specifications describe the type of height data required by road design and priority of acquisition. In addition, we performed a survey of the needs of road designers and a fact-finding survey of topographical map data in Japan. Based on the results of these studies, these preparation specifications are organized. Additionally, we used case studies to verify the data reproducibility.