Step 3. Select Sites for Investigation
The outcome of a network screening activity (Step 2) is either a list of high crash locations or a crash map. In an ideal situation, every identified site would be analyzed in more detail. However, due to time and resource constraints, it may not be possible to study all sites in depth. In this step, the locations identified in Step 2 (network screening) are reviewed and evaluated to determine which of them should be selected for detailed analysis (Steps 4 through 7). Selecting sites for detailed analyses will be a qualitative process and will rely on considerations like relative severity and frequency of crashes at the site, traffic volumes, stakeholder concerns, potential solutions. While not an exhaustive list at all, some reasons to select a site for more detailed analysis could be:
- The site is ranked high on a screening list when using quantitative screening criteria – e.g., crashes, crash rates;
- There is a grant funding program targeted at issues comparable to those expected at the site;
- There is an upcoming maintenance or construction project in the vicinity of the site where the safety improvement could be integrated into the project;
- Improving the site would be consistent with other agency plans, policies or programs; or
- Of the crashes that have occurred, a large proportion have resulted in fatalities or serious injuries.
The number of sites selected for detailed analysis depends greatly on the staff or consultant resources available to the agency as well as the extent to which the agency can fund corrective actions. A site summary selection process example is shown in Table 4. The table displays the types of information practitioners might consider in the site selection process, i.e., background data, evaluation considerations, and the results of site evaluation and prioritization processes. Note that Location D would rank high based on network screening using crash rates, however in this hypothetical it is not selected for further investigation for two reasons: 1) the traffic volume through the intersection is extremely low; and 2) there was only one crash at this location and it was a property damage only crash. Therefore, relatively speaking, there is no significant issue at this site. This example also demonstrates how the best use for crash rates is when the sites have comparable traffic volumes and comparable roadway characteristics.
It is important to document safety analysis findings. Documentation allows others to verify the findings and to repeat the activity again in the future.
Site selection can be finalized collaboratively among staff familiar with the community, or determined by the responsible staff member. Site selection decisions should be documented by noting which sites were and were not selected as well as the reasons behind the decision. Community members or stakeholders familiar with the safety issues also can provide valuable input to the site selection process. If there is sufficient interest, a standing community traffic safety committee could be organized to provide input and advocate for traffic safety. User Guide #2 provides a detailed example of the site selection process across multiple sites.