Intersections Rural Roads Operations and Maintenance Advisory - - PowerPoint PPT Presentation

Intersections

Rural Roads Operations and Maintenance Advisory Committee Thursday, October 10, 2019

Intersection Control Evaluation

• Intersection traffic control study is

completed when significant changes to an intersection are under consideration.

• The purpose is to determine the

most appropriate form of traffic control.

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Intersection Control Evaluation

• The study evaluates the alternatives

and considers the benefits of each.

• Considerations include:

‒ Safety performance ‒ Operational performance ‒ Environmental impacts ‒ Right-of-way impacts ‒ Access management ‒ Operations and maintenance costs

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Safety Analysis

• Identify safety concerns and how

they will be resolved for each alternative.

• Safety concerns include:

‒ Sight distance ‒ Roadway alignment ‒ Speed ‒ Crash history

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Safety Analysis

• Safety concerns include (cont.):

‒ Accommodating all modes of transportation (pedestrians, bikes, transit) ‒ Railroad crossings ‒ Nearby access movements ‒ Accommodating trucks and farm equipment

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Operational Analysis

• Capacity analysis
• Queuing analysis
• Signal warrants analysis
• Other operational analysis as

appropriate for each alternative.

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Operational Analysis

• This analysis will consider the ability
• f each alternative to accommodate

a variety of users

• Trucks
• Farm equipment
• Transit buses
• Bicycles
• Pedestrians
• Automobiles

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Additional Considerations

• Transportation Plan Consistency
• The alternatives must be consistent

with the transportation plan.

• Funding and maintenance
• The alternatives considered must fit

within the project budget and also within the long-term maintenance budget.

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Additional Considerations

• Public input
• Impacts to sensitive areas, streams

and wetlands

• Nearby property impacts and

impacts to accesses

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Where to exercise care with roundabouts?

• Physical or geometric complications
• Proximity of significant generators
• Proximity of other traffic control devices
• Proximity of bottlenecks
• Problems with grades and unfavorable topo
• Intersection of major road with minor
• Heavy ped and/ or bike movements
• Located within a coordinated signal network

Applied Roundabout Design, Kittelson & Associates, Inc.

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Geometric elements of a roundabout (NCHRP Report 672)

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Roundabout Category Comparison (NCHRP Report 672)

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Features of a typical mini-roundabout (NCHRP Report 672)

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Features of a typical single-lane roundabout (NCHRP Report 672)

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Features of a typical two-lane roundabout (NCHRP Report 672)

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Vehicle conflict point comparison (NCHRP Report 672)

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Vehicle-Pedestrian conflicts comparison (NCHRP Report 672)

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Chance of pedestrian death if hit by a vehicle (NCHRP Report 672)

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Roundabout Field Testing

• US20 & OR47 roundabout testing

‒ Portland Meadows (March 2015)

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Roundabout testing footage

Freight Field Testing

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Farm Equipment Field Testing

Roundabout testing footage

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Verboort/ OR47

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David Hill/ OR47

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Jackson School Rd

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Curb Details

Truck Apron Section Curb and Gutter Section

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Martin Rd / OR47 Alternatives

• An intersection control

analysis was conducted.

• Alternatives evaluated:
• No-build
• Signalized intersection
• Roundabout

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The preferred

• ption is the

roundabout

• Greater safety benefits

than the signalized intersection.

• Lower maintenance costs.

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Turning movements tested

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Martin Rd / OR47 Project Status

• The project was presented to the Freight Mobility

Advisory Committee June 13, 2019.

‒ No decision at this time. The project will need to present at a future meeting.

• 50% design review completed.
• An open house was held on July 31, 2019.
• An update will be provided to the Forest Grove

City Council on December 9, 2019.

• The project is anticipating to bid in fall of 2020.
• The project is anticipating construction starting

in spring of 2021.

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Questions?

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