Safety at Unsignalized Intersections Safety at Unsignalized - - PowerPoint PPT Presentation

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Safety at Unsignalized Intersections Safety at Unsignalized - - PowerPoint PPT Presentation

Jul 12, 2023 253 likes •679 views

Safety at Unsignalized Intersections Safety at Unsignalized Intersections Unsignalized Intersections FHWA Safety Focus Areas FHWA Safety Focus Areas Unsignalized Intersections Unsignalized Intersections 2 National Statistics National

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Unsignalized Intersections

Safety at Unsignalized Intersections Safety at Unsignalized Intersections

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Unsignalized Intersections Unsignalized Intersections

FHWA Safety Focus Areas FHWA Safety Focus Areas

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Unsignalized Intersections Unsignalized Intersections

National Statistics National Statistics

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Unsignalized Intersections Unsignalized Intersections

National Statistics National Statistics

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Non-Intersections 79% Intersections 21%

There were 41,059 highway fatalities There were 41,059 highway fatalities in 2007. Where did they occur? in 2007. Where did they occur? About half of About half of all all crashes and crashes and half of all injury crashes half of all injury crashes

  • ccur at intersections.
  • ccur at intersections.
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Unsignalized Intersections Unsignalized Intersections

Intersection Fatalities Intersection Fatalities

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1,000 2,000 3,000 4,000 5,000 6,000 Arterial Collector Local Unknown

5,232 1,472 214 1,739

There were 8,657 intersection fatalities in 2007. There were 8,657 intersection fatalities in 2007. Where did they occur? Where did they occur? 39% in 39% in rural areas rural areas 61% in 61% in urban areas urban areas

Fatalities

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Unsignalized Intersections Unsignalized Intersections

Intersection Fatalities Intersection Fatalities

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Unsignalized Intersections Unsignalized Intersections

Intersection Safety Guidance Intersection Safety Guidance

  • NCHRP Report 500 Volume 5
  • Guide sheets
  • Safety Strategies brochure

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Unsignalized Intersections Unsignalized Intersections

Typical Intersection Crash Types Typical Intersection Crash Types

  • Right angle
  • Rear end
  • Left turn
  • Sideswipe
  • Pedestrian/bicycle

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Unsignalized Intersections Unsignalized Intersections

Crash Reduction Factors Crash Reduction Factors

  • Quantitative results from

research or other studies

  • Expected reduction in

crashes from implementation of a specific countermeasure

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Unsignalized Intersections Unsignalized Intersections 10

Angle Crashes Angle Crashes

  • Account for 53% of fatal crashes

at unsignalized intersections

  • Potential countermeasures:

– Clear sight triangles – Improve awareness of intersection – Apply access management – Improve turn lane design – Construct roundabouts – Construct acceleration lanes – Close/relocate intersections – Reduce/eliminate skew – Post appropriate speed limits – Targeted enforcement

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Unsignalized Intersections Unsignalized Intersections

Clear Sight Triangles Clear Sight Triangles

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Unsignalized Intersections Unsignalized Intersections

Improve Awareness of Intersection Improve Awareness of Intersection

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Double Warning Signs Oversize Signs

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Unsignalized Intersections Unsignalized Intersections

Improve Awareness of Intersection Improve Awareness of Intersection

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Splitter Island Supplemental Beacons

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Unsignalized Intersections Unsignalized Intersections

Improve Awareness of Intersection Improve Awareness of Intersection

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Provide Lighting Install Rumble Strips

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Unsignalized Intersections Unsignalized Intersections

Apply Access Management Apply Access Management

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Right-in/Right-Out Channelization

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Unsignalized Intersections Unsignalized Intersections

Improve Turn Lane Design Improve Turn Lane Design

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Offset Right Turn Lane

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Unsignalized Intersections Unsignalized Intersections

Construct Roundabouts Construct Roundabouts

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Unsignalized Intersections Unsignalized Intersections

Construct Left Construct Left-

  • Turn Acceleration Lanes

Turn Acceleration Lanes

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Acceleration Lane Through Lanes

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Unsignalized Intersections Unsignalized Intersections

Close / Relocate Intersection Close / Relocate Intersection

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Unsignalized Intersections Unsignalized Intersections

Reduce/Eliminate Skew Reduce/Eliminate Skew

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New alignment New alignment

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Unsignalized Intersections Unsignalized Intersections

Post Appropriate Speed Limits on Approaches Post Appropriate Speed Limits on Approaches

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Unsignalized Intersections Unsignalized Intersections

Targeted Enforcement Targeted Enforcement

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Speed violations Stop violations

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Unsignalized Intersections Unsignalized Intersections 23

Rear End Crashes Rear End Crashes

  • Account for 6% of fatal crashes

at unsignalized intersections

  • Potential countermeasures:

– Install turn lanes – Supplemental overhead signing – Provide shoulder bypass lanes – Provide pavement markings – Provide right-turn acceleration lanes – Construct roundabouts* – Provide left-turn acceleration lanes* – Provide lighting* – Post appropriate speed limits* – Improve intersection awareness*

* Discussed previously

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Unsignalized Intersections Unsignalized Intersections

Install Turn Lanes Install Turn Lanes

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Left turn lanes Right turn lanes

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Unsignalized Intersections Unsignalized Intersections

Supplemental Overhead Signing Supplemental Overhead Signing

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Unsignalized Intersections Unsignalized Intersections

Provide Shoulder Bypass Lanes Provide Shoulder Bypass Lanes

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Unsignalized Intersections Unsignalized Intersections

Provide Pavement Markings Provide Pavement Markings

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Unsignalized Intersections Unsignalized Intersections

Provide Right Provide Right-

  • Turn Acceleration Lanes

Turn Acceleration Lanes

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Unsignalized Intersections Unsignalized Intersections 29

Left Turn Crashes Left Turn Crashes

  • Account for 8% of fatal crashes at

unsignalized intersections

  • Potential countermeasures:

– Improve turn lane design – Implement turn restrictions – Use indirect left turn treatments – Provide lighting* – Clear sight triangles* – Provide left turn acceleration lanes* – Construct roundabouts* – Close/relocate high-risk intersections*

* Discussed previously

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Unsignalized Intersections Unsignalized Intersections

Improve Turn Lane Design Improve Turn Lane Design

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Unsignalized Intersections Unsignalized Intersections

Improve Turn Lane Design Improve Turn Lane Design

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Unsignalized Intersections Unsignalized Intersections

Implement Turn Restrictions Implement Turn Restrictions

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Unsignalized Intersections Unsignalized Intersections

Use Indirect Left Turn Treatments Use Indirect Left Turn Treatments

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Unsignalized Intersections Unsignalized Intersections 34

Sideswipe Crashes Sideswipe Crashes

  • Account for 2% of fatal crashes

at unsignalized intersections

  • Potential countermeasures:

– Install pavement markings – Provide lane assignment signing or marking – Provide right-turn acceleration lanes*

* Discussed previously

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Unsignalized Intersections Unsignalized Intersections

Provide Striping in Median Area Provide Striping in Median Area

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Unsignalized Intersections Unsignalized Intersections

Lane Assignment Signing/Marking Lane Assignment Signing/Marking

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Unsignalized Intersections Unsignalized Intersections 37

Pedestrian/Bicycle Crashes Pedestrian/Bicycle Crashes

  • Account for 14% of fatal crashes

at unsignalized intersection crashes

  • Potential countermeasures:

– Improve pedestrian/bicycle facilities – Provide traffic calming – Information and education

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Unsignalized Intersections Unsignalized Intersections

Improve Pedestrian/Bicycle Facilities Improve Pedestrian/Bicycle Facilities

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Continuous/Setback Sidewalks Advance crossing warning

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Unsignalized Intersections Unsignalized Intersections

Provide Traffic Calming Provide Traffic Calming

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Pedestrian bulb-outs Neighborhood circles

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Unsignalized Intersections Unsignalized Intersections 40

Information and Education Information and Education

Web sites Web sites Web sites Printed material Printed material Printed material Speed trailers Speed trailers Speed trailers Community outreach Community outreach Community outreach In school programs In school programs In school programs Radio and TV Radio and TV Radio and TV

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Unsignalized Intersections Unsignalized Intersections 41

For More Information For More Information

  • AASHTO Report 500 Series Volume 5

– http://safety.transportation.org/

  • Manual on Uniform Traffic Control Devices

– http://mutcd.fhwa.dot.gov/

  • Toolbox on Intersection Safety and Design

– http://www.ite.org/

  • FHWA Office of Safety

– http://safety.fhwa.dot.gov/