Road Safety Audits (RSA)

APPENDIX A
RSA CASE STUDIES

RSA NUMBER 2

OKLAHAMA DEPARTMENT OF TRANSPORTATION:
RSA OF IMPROVEMENTS TO CLEAR LAKE AVENUE AND DIRKSEN PARKWAY

PROJECT BACKGROUND:

US 60 is a US numbered highway (part of the National Highway System) extending for 350 miles across northern Oklahoma. The RSA team reviewed detailed (90 percent) design stage drawings of upgrades to a 2.9-mile stretch of US 60 in Osage County. Along the upgraded section, US 60 has a posted speed limit of 65 mph, and a reported AADT of 3,500 vehicles. The existing roadway, shown in FIGURE A.3, is a two-lane rural roadway having 12-foot driving lanes with narrow or absent paved shoulders. In addition to resurfacing, the upgrades included:

• replacing existing bridges over Buck Creek and Turkey Creek, including reconstructing the approach roadways as two 12-foot lanes with 8-foot paved shoulders;
• between the bridges, widening shoulders to provide a continuous 8-foot paved shoulder and adding one channelized right turn lane at the unsignalized intersection with Bowring Road, a section-line road;
• resurfacing a 1.2-mile “incidental section” west of Buck Creek (12-foot lanes with 2-foot paved shoulders) to connect with an adjacent segment of US 60 further west that had been recently overlaid.

The RSA team also reviewed proposed construction-stage detours.

Buck Creek bridge (planned improvements include repaving, bridge improvements, and 8’ paved shoulders)	adjacent “incidental” section (planned improvements include repaving and 2’ paved shoulders)

FIGURE A.3 VIEWS OF RSA SITE (OKLAHOMA DOT RSA)

KEY RSA FINDINGS AND SUGGESTIONS:

The key findings and suggestions of the RSA are summarized in TABLE A.2. The DOT responded that changes would be made as suggested except for changes that would involve re-negotiation with property owners or utility relocation (Issue 1), since these processes were already complete, or changes that would entail substantial delay or additional expense (redesign of cross-section elements on the incidental section, Issue 2D). The DOT also declined the suggestion to install rumble strips, since they are not typically used on Oklahoma highways.

KEY LESSONS LEARNED:

It is important to identify the safety benefits of the design as part of the RSA process. The improvements to US60 were motivated largely by safety, to provide a consistent and high-quality roadway where the existing roadway was characterized by poor pavement and roadside conditions. As part of the RSA process, the RSA team identified how the elements of the Design Team’s proposed improvements were expected to positively address existing safety concerns. Examples cited in the RSA report included the following:

• Paved 8-foot shoulders and shallower fill slopes will reduce the risk and severity of off-road collisions.
• Resurfacing will improve the travel surface, and new pavement markings will improve driver guidance.
• Bridge reconstruction will increase the clearance distance to roadside safety issues, and provide the opportunity to improve barrier end treatments.

Acknowledging the safety benefits of the original design put the RSA findings in an appropriate context.

See also the discussion of “Key Factors for Success” and “Lessons Learned” in the main text.