WSDOT - Active Transportation Route Directness Index Points

This feature class represents the points that were used for the Route Directness Index calculation. These points were generated along the increasing state routes as represented by the 12/31/2023 WSDOT LRS. Points were only generated within Population Centers (using the Population Centers dataset obtained from the GIS Workbench in January 2025). Every 0.01 mile (52.8 feet) along the route a transect was created perpendicular to the route extending 500 feet on each side of the route. These points represent the midpoint of each transect. The Route Directness Index (RDI) is a ratio that compares the straight-line (crow-flies) distance from one point to another across a barrier to the actual distance imposed by the network of paths available to a traveler. RDI data is particularly relevant to pedestrian and/or bicyclist trips due to the extra time, physical energy, and exposure to weather that out of direction travel creates. A complete discussion of route directness, including potential applications to decision making, can be found Washington State Multimodal Permeability Pilot, August 2021 [https://wsdot.wa.gov/sites/default/files/2021-11/MultimodalPermeabilityPilotReport-Aug2021.pdf]. RDI can be analyzed at different scales. A high-level analysis of RDI can address questions that compare population centers across the state or consider whether the RDI values are generally similar within a given population center or tend to vary in different portions of a population center. High level data could be combined with other statewide data such as crash data, transit stops, level of traffic stress data, destination data, etc. to analyze potential correlations. High level RDI data is less useful for analyzing a particular crossing location or recommending solutions to address high RDI values. A more detailed analysis is likely required when questions involve corridor studies or project evaluations. Detailed location information can refer to key destinations and crossing locations that are not captured using higher level network maps. The lowest RDI is 1 because a trip between those points can be made directly along an existing roadway. The actual methodology analyzed hypothetical trips where the start and end points were about a quarter mile apart relative to a straight line. In such a situation, an RDI of 2 would mean the trip is twice the distance it might otherwise be, or about one-half mile. Although one-half mile is not particularly far, the RDI is independent of the actual distance. We might start further down the road and if the RDI remained a 2 our trip distance would be twice as long as it could have been. The RDI thus measures the real or perceived burden or travel cost incurred by a person walking or bicycling.

本要素类代表用于路线直达指数（Route Directness Index, RDI）计算的点位。这些点位沿2023年12月31日版华盛顿州运输部（Washington State Department of Transportation, WSDOT）路线参考系统（Linear Reference System, LRS）所标注的新增州级路线生成，且仅生成于人口中心范围内（人口中心数据集取自2025年1月的GIS工作台）。沿路线每间隔0.01英里（即52.8英尺）创建一条垂直于路线的样带，该样带在路线两侧各延伸500英尺，本类点位即为每条样带的中点。路线直达指数（RDI）是一类比值，用于对比受障碍物阻隔时两点间的直线（即“乌鸦飞”）距离，与旅行者可通行路径网络所实际要求的通行距离。由于绕行会增加出行时间、消耗更多体力并延长暴露在天气中的时长，RDI数据对步行及自行车出行场景尤为相关。关于路线直达性的完整讨论（包括其在决策中的潜在应用）可参阅《华盛顿州多模态渗透性试点项目》（2021年8月）[https://wsdot.wa.gov/sites/default/files/2021-11/MultimodalPermeabilityPilotReport-Aug2021.pdf]。RDI可在不同尺度下开展分析。高层次的RDI分析可用于解答两类问题：对比全州范围内的人口中心通行直达性，或探究某一给定人口中心内部的RDI值整体是否趋于一致，或是在人口中心不同区域呈现差异。高层次RDI数据可与其他全州级数据（如事故数据、公交站点数据、交通压力等级数据、目的地数据等）结合，以分析潜在相关性。但高层次RDI数据在分析特定过境点位或针对高RDI值提出解决方案时实用性较弱。当研究问题涉及廊道研究或项目评估时，通常需要开展更细致的分析。精细化的点位信息可涵盖高层次路网地图未捕捉到的关键目的地与过境点位。RDI的最小值为1，此时两点间可沿现有道路直接通行。本方法论所分析的假想出行场景中，起点与终点的直线间距约为0.25英里。在此场景下，若RDI为2，则意味着实际通行距离是直线距离的2倍，即约0.5英里。尽管0.5英里并不算远，但RDI的取值与实际通行距离无关。例如，若从更远处出发且RDI仍为2，则实际出行距离仍为直线距离的2倍。由此可见，RDI用于衡量步行或骑行者所承担的实际或感知到的出行负担与出行成本。