Intersection safety is a priority for many communities wanting to address the high proportion of severe collisions occurring at intersections. In 1996, AAA Michigan initiated the Road Improvement Demonstration Program (RIDP), an innovative roadway improvement program involving public-private funding and multijurisdictional cooperation that has improved safety at targeted high-crash intersections in Detroit and Grand Rapids, Mich. The RIDP is based in part on an extensive program of developing partnerships to identify hazardous intersections, conduct in-service road safety audits and implement improvements.
Independent evaluations of the RIDP in Michigan indicated that as a result of implementing the recommendations from the in-service safety audits, total crashes decreased by more than 25% and total injuries decreased by more than 40%. As a result of this success, AAA Michigan’s sister automobile club, AAA Wisconsin, decided to develop a similar partnership in the Milwaukee area.
Power steering
Involvement by road agencies begins with initial discussions on whether to formally partner with AAA Wisconsin and participate in the RIDP. In early 2004, AAA Wisconsin representatives set up meetings with local politicians, transportation officials and engineers to discuss the merits of their agencies’ participation in the RIDP. Once all of the local, county and state agencies agreed to participate, a steering committee was set up to coordinate and oversee the implementation of the RIDP. The steering committee included representatives from the city of Milwaukee, Milwaukee County, Wisconsin Department of Transportation (WisDOT), Federal Highway Administration’s Wisconsin Division, Southeast Wisconsin Regional Planning Commission, Milwaukee County Transit and five Milwaukee-area suburbs (Franklin, Greenfield, Oak Creek, Wauwatosa and West Allis). One of the primary functions of the steering committee was to oversee the audit process.
Opus International Consultants was chosen by AAA Wisconsin to conduct in-service road safety audits for the RIDP. These audits identify the causes of collisions and recommend mitigation measures at high-risk intersections. Opus had earlier partnered with AAA Michigan and the Insurance Corp. of British Columbia to establish the process for similar road improvement programs and had extensive experience in conducting in-service audit programs for urban intersections and corridors.
One of the main obstacles to a successful audit program is an understandable apprehension on the part of the road agency’s engineers that the process will generate an extensive list of safety issues for which potentially costly solutions will be identified, which must subsequently be funded using limited financial resources.
To address these concerns, the RIDP program has implemented two important measures:
- A procedure to ensure the ongoing participation and involvement of the agency in the audit process; and
- A countermeasure funding strategy to leverage federal, state, county or city funds.
Target time
Intersections that are identified for study under the RIDP are chosen by considering many factors. These factors take into account collision data, available funding and the agency’s long-range transportation plan. The goal of this process is to identify the specific intersections with the highest potential for improvement using low-cost solutions. Using data from the WisDOT computerized crash database, intersections were ranked using traditional methods such as collision frequency, severity, type and rate.
Once intersections are identified through this process based on crash data, they are then vetted in consultation with the partnering road agency. In many cases, the road agency will suggest a safety audit at intersections where resurfacing or routine maintenance is planned. At these intersections, recommended safety improvements can potentially be included with planned maintenance activities at little or no additional cost. The vetting process also screens intersections that are not suitable for study, such as those at which improvements have recently been made, or at which high collision rates reflect anomalous or transient conditions such as construction activities.
Additionally, intersections where suggested improvements that are likely to require higher-cost mitigation measures such as grade separation, right-of-way acquisition or substantial roadway realignment are typically not included. By combining the crash data with this vetting process, the targeted intersections will have both a high potential for safety improvement and can take into account agency budgets and long-range plans.
On a crash diet
The first step of the safety audit is to contact the road agencies involved and request they provide background information on the intersection. This information is generally related to roadway geometrics, traffic-control devices, traffic volumes, signal timings, aerial photographs and any other relevant past studies.
WisDOT provides digital images of the police crash reports (MV4000 forms) for the area surrounding each of the intersections. By analyzing the individual crash reports, it is possible to verify whether the crash type coded by the police officer is correct, identify the precise location of the crash and examine the reporting officer’s comments and drawings. In most cases the officer’s comments and drawings will clarify what happened in each collision.
Once all of this background information has been collected, a startup meeting is held with all of the stakeholders involved. The meetings typically include representatives from the road agency’s engineering staff, local police officers, AAA’s traffic engineer and the Opus engineers conducting the audits. During this startup meeting, the road agency’s engineers are asked to identify specific constraints and issues that will affect possible mitigation measures. Some examples of issues that have been brought up at recent meetings are as follows:
- Residents are complaining about speeding on some approaches;
- A business that generates substantial vehicle and pedestrian traffic is relocating from one intersection quadrant to another;
- City council will not allow the removal of on-street parking; and
- Many of the pedestrians crossing at the intersection are transferring buses and consequently may disregard pedestrian signals to make their connections.
Following the startup meeting, the audit team conducts site visits. Typically, the team visiting the sites includes a representative of Opus, AAA Wisconsin and the road agency. In some cases, a police officer will meet the audit team at the intersection to discuss enforcement issues related to the site. During the site visit, the audit team will typically observe the road-user characteristics, surrounding land uses and link points to the adjacent transportation network from the perspective of all users. The interaction between drivers, pedestrians, bicyclists and transit is considered.
In addition, the following human factors issues also are considered:
- Intersection conspicuity;
- Visibility of the traffic-control devices;
- Intersection readability;
- Sign location and sequencing;
- Older-driver limitations; and
- Driver perception of geometric features constructed to minimum standards.
The audit team visits the intersection at different times of the day to observe the changing traffic patterns. During these visits, the audit team will observe the intersection from each approach and use all pedestrian crossings. Using the pedestrian crossings allows the audit team to observe the intersection from the perspective of the pedestrian. While observing the intersection, digital photographs are taken of each approach and of the items discussed in the previous lists. These photographs are used within the report and in future presentations. In addition, members of the team will spend time driving through the intersection during both peak and off-peak traffic conditions. Driving through the intersection and completing all turns allows the audit team to observe intersection geometry and operations from the perspective of the driver.
Once completing the site visits, the audit team will reconvene and compare notes. At this point, the audit team will brainstorm to identify safety issues and potential mitigation measures and will develop presentation materials for the preliminary findings meeting, typically held immediately following the initial set of site visits. At the preliminary findings meeting, the audit team and all of the stakeholders meet to discuss the results of the site visits. The audit team will present preliminary findings and potential mitigation alternatives. The goal of presenting these alternatives is to obtain the agencies’ input regarding whether specific mitigation measures are feasible and worth considering while preparing the report.
Following the preliminary findings meeting, the audit team liaises with road agency staff and the AAA traffic engineer to obtain additional information, keep everyone informed of progress and ensure the agency’s continued input to the process of identifying feasible mitigation measures.
At the conclusion of the audit program, the audit team issues a report containing their findings and recommendations. Opus first releases a draft version of the report to AAA Wisconsin and the road agency for their comments and further input. The final report incorporates changes resulting from comments.
Report’s card
One of the most important pieces of an effective audit program is to produce an effective report. The audit report documents the background, findings and recommendations of the in-service audit. The format of the report has evolved with the RIDP, with the ultimate aim of producing a report that is comprehensive and concise, being mindful of the time demands on road agency engineers.
To meet both requirements, a standardized format has been established. Key findings and recommendations are graphically summarized for quick reference in a freestanding executive summary. Many of the agencies will use the executive summary as the basis for project funding applications. More detailed documentation is provided in the main report, which has chapters relating to:
- Introduction and background;
- Existing geometry and operations;
- Collision history;
- Identification of safety issues and deficiencies;
- Identification of mitigation measures and improvement strategy; and
- Benefit-cost evaluation.
Information is summarized graphically for all but the first and last chapters, and these summary graphics form the executive summary. Supporting documentation such as software outputs and intersection photographs are provided in appendices to the audit report.
Once the report is complete, AAA Wisconsin will meet with all of the road agencies having jurisdiction over the intersection.
In many cases, up to three separate road agencies have been involved. The objectives of these meetings are to discuss the audit reports and confirm that recommended mitigation measures are feasible for implementation.
Substantive discussions on how to fund the improvements also take place at these meetings. Once a plan for improvement has been developed, the road agency will then apply for funds to implement the improvements.
Eye on 49
Since the Wisconsin RIDP was launched in 2004, safety audits have been conducted at 27 intersections in the Milwaukee area. In 2005, the RIDP was extended to Madison. In the Madison area, AAA Wisconsin is partnering with the city, Dane County, WisDOT, the city of Fitchburg and FHWA to conduct in-service safety audits. In 2006, Waukesha County was added to the Milwaukee-area partnership. To date, 49 intersections (40 in the Milwaukee area and nine in the Madison area) have been audited. Improvements have been constructed at six intersections, and funding has been approved to implement improvements at 15 additional sites.
The main reason why agencies agree to join the AAA RIDP partnership is that, while they typically have a program to identify high-crash locations and develop countermeasures, the ability to partner with AAA vastly expands the number of locations that can be reviewed. This partnership that AAA organizes and facilitates promotes the vision of multijurisdictional cooperation. By working in partnership with many agencies in a combined effort, it allows the whole RIDP to become more effective in reducing crashes. The reason the RIDP has been so successful in implementing safety improvements is that AAA has the ability to develop and sustain partnerships and promote a common vision. By working in partnership, many more sites can be reviewed and safety improvements can be implemented.
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