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44 C h a p t e r 7 This SHRP 2 project dealt with the design and development of the RID. The research team was able to design and build the RID with data from the mobile data collection project, existing roadway inventory data from public and private agencies, and supplemental data to support the safety mis- sion of SHRP 2. The RID was designed to accommodate dis- parate data sets, store these data in the most natural format, and facilitate integration of these data, as well as a linkage with the NDS vehicle and driver data. The RID provides con- text for a substantial part of the more than 5 million NDS trips and will enable researchers to study the impact of roadway data on safety. As with any other effort, there were some challenges and les- sons learned throughout the process. The following describes the challenges faced and the lessons learned: 1. The SHRP 2 Safety study was the largest of its kind to date, and building the RID to address multiple research ques- tions was complex and required major tradeoffs between cost, time requirements, and complexity of the system. The research team used existing safety literature, SHRP 2 Safety projects that developed research questions, and input from researchers covering a wide range of safety research to develop a list of critical roadway attributes to be collected. 2. The discovery of existing data (whether state, local, or pri- vate sources) proved beneficial to the RID. There were challenges in terms of data access and sharing for nonstate DOT data that limited the amount of data that ended up being acquired as part of the RID. 3. Evaluating mobile data collection technology and services is not a trivial task. Knowledge of the usersâ requirements, funding constraints, and accuracy requirements is critical to selecting the right contractor for the job. In the end, the team, in cooperation with SHRP 2, was able to qual- ify three contractors to submit proposals for roadway data collection. 4. With six study sites around the United States, it was criti- cal to use a consistent roadway network to build the linear referencing system for the RID. Using the Esri/NAVTEQ road network made it possible to integrate and link data from different sources for the RID and enabled the linking of the RID and NDS data. 5. Developing a process for selecting roads for the mobile data collection in each site allowed the research team to opti- mally allocate the collected miles between sites and within each site. Using GPS traces from the volunteer drivers made it possible to select roads where NDS participants drove. Using GIS tools was critical to making this process work smoothly and efficiently. 6. Collecting quality data was deemed paramount to the suc- cess of the RID. Even though only the data collected through the mobile data collection project went through the quality assurance process, these data will provide researchers with the most accurate roadway information available across multiple sites. The quality assurance process was the result of constant communication and coordination between the team conducting the quality assurance and the team collecting the data. 7. The pilot data collection effort was a key aspect in success- fully acquiring the mobile data on such a large and dis- persed scale. This small-scale effort provided the research team with the necessary information to improve and cus- tomize the process for routing, collecting, processing, and conducting quality assurance. Conclusions
