Sonoita Crossroads Community Forum

Meeting Two Challenges:
Enhancing Safety & Preserving the Scenic Qualities of SR83

A Joint Presentation by:

ADOT Highway Enhancements for Safety (HES) Section

Development and Construction Review Committee of the Sonoita-Patagonia Scenic Road Advisory Council

Origin of this Presentation

In an analysis of the pattern of accidents on SR83 over a 5 year period, a decision was made by ADOT HES that action is needed to enhance safety on a section of SR 83. A discussion of the analysis and mitigation strategies was held with the Development and Construction Review Committee (DCRC) of the Scenic Road Advisory Council (SRAC). An agreement was reached between ADOT and the DCRC to vet all proposed projects with the community.

Goals of this Presentation

We wish to inform the citizens of NE Santa Cruz County regarding a proposed safety enhancement project and to seek constructive commentary. We wish to inform the community regarding:

1. Options for providing comments and input during the design process and
2. How to access information regarding the evolution and status of the proposed project.

Introduction to the HES Section of ADOT

ADOT's Highway Enhancements for Safety (HES) Section is concerned primarily with enhancing the safety of all state highways within Arizona through the engineering of construction projects.

ADOT's HES Section identifies, develops, designs, constructs, and evaluates safety improvement projects on state highways containing locations, sections, or elements that can benefit from safety enhancements.

HES: Overview of Methods

The HES Section identifies needs for safety enhancement by:

• analyzing collisions/crashes within the state highway system;
• looking for crash patterns ;
• defining projects to mitigate safety issues.

The Elements of Driving

Driving involves a complex interaction between the Driver(or User), the Vehicle, and the Roadway.

A crash may be the result of an error or breakdown of any one or a combination of these.

HES Responsibility

HES must ensure that the physical roadway is as safe as possible for all road users.

HES must ensure that the physical roadway yields the most straightforward, consistent messages to the driver.

The Context: 2004 Statewide Statistics

Run-Off-Road (ROR) accidents account for 42% of all Arizona fatalities.

Motorcycle related collisions account for 11% of all Arizona Fatalities. 83% of all motorcycle crashes result in injury or death.

Why Safety on SR83 is a Concern

SR 83 near MP 45 ranks 8th highest in the State Highway System for ROR crashes.

SR 83 between MP 44 & 45 ranks 1st highest among locations in the State Highway System experiencing motorcycle related collisions.

Analysis of SR83 MP 44-45 Collisions

A five year study of 55 serious/fatal accidents shows the following:

• 79% are Run-Off-Road accidents
• 93% are single-vehicle accidents
• 55% are motorcycle collisions (the remaining 45% involve cars or light trucks)
• 70% occur in daylight
• 86% are on dry pavement
• 92% have no vehicle defect
• 72% have no driver defect
• 75% involve speeding
• 57% occur on Saturday/Sunday
• 88% are northbound

Collision Diagram – MP 43.95 to MP44.75

Roadway Characteristics

The roadway was designed & built between 1955-56.

• The curves were constructed in a "tangent-to-curve" design;
• The design considered "natural"/existing, topography;
• The existing transitions don't include spiral curves.

The central of the three reverse curves between MP 44.0 & approximate MP 44.6 is shorter in length and has a smaller radius than the adjacent curves.

Highway construction standards have changed.

Safety can be enhanced by modifying roadway alignment; e.g., curve reconstruction, shoulder improvements.

Mitigation Strategies Considered

1. Decreasing the driver's speed is difficult to control.
   • Human behavior is difficult to change.
   • Mitigation strategies (e.g. transverse rumble strips) have both positive & negative effects.
2. Widen the shoulders of the road
3. Install shoulder rumble strips.
4. Modify signing, marking, and delineation
5. Change the 'tilt' of the curve (like tilting the walls of a racetrack)
6. Increase the radius of the curve by realigning the road
   • Make its radius and length at least equivalent to thesmaller of the adjacent curves

SR 83 Proposed Action

Safety in this region can be enhanced by modifying roadway alignment; e.g., curve reconstruction, shoulder improvements.

How ADOT Proposes to Proceed

• Inform the community of the need and proposedmitigation strategy (this meeting).
• Meet with the DCRC onsite and in Tucson.
  • Prior to this, ADOT needs to collect data via a survey
• Discuss plans with DCRC and the community.
• Work with DCRC to come up with the best plan.
• Hold with high value:
  • Minimizing the impact on the scenic nature of SR83
  • The concerns of the local community

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