Transcript Presentation - Subcommittee on Design

Status of the AASHTO Roadside
Design Guide Update
Annual AASHTO Subcommittee on Design Meeting
July 25-29, 2010 Columbia, South Carolina
Rod Lacy, P.E.
Kansas Department of Transportation
July 27,2010
2010 SCOD Columbia, SC
RDG Update Objectives
 Statistics Updated
 Incorporated Research
 Incorporated AASHTO “MASH” document
 Referenced safety hardware websites for
designer use.
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2010 SCOD Columbia, SC
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RDG 2010 – Highlights of Changes

Chapter 1 – An Introduction to Roadside
Safety
– Updated roadside crash statistics
– References FHWA Acceptance Letter Web Site
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2010 SCOD Columbia, SC
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Percent distribution of fixed-object fatalities by object struck, 2008
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1975-2008
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RDG 2010 – Highlights of Changes

Chapter 2 – Economic Evaluation of
Roadside Safety
– Editorial updating only
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2010 SCOD Columbia, SC
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RDG 2010 – Highlights of Changes

Chapter 3 – Roadside Topography and
Drainage Features
– “Clear-Zone” terminology coordinated with
Green Book
– Clear-Zone for auxiliary lanes defined
– Curb discussion moved to Chapter 5
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2010 SCOD Columbia, SC
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RDG 2010 – Highlights of Changes

Chapter 4 – Sign, Signal, and Luminaire
Supports, Utility Poles, Trees, and Similar
Roadside Features
– Update breakaway discussion re: MASH –
pickup test, windshield damage, roof crush
– Cites MUTCD Breakaway Requirement
– Recommends breakaway devices in urban
areas
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2010 SCOD Columbia, SC
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RDG 2010 – Highlights of Changes

Chapter 4 – Continued
– Requires electrical quick disconnect devices
– Emphasizes the need for omni-directional
supports in various locations
– Discusses high mast lighting supports and
traffic signal supports
– Refers to NCHRP Report 500, Volume 8 for
dealing with utility poles
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2010 SCOD Columbia, SC
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RDG 2010 – Highlights of Changes

Chapter 5 – Roadside Barriers
– References MASH and Implementation Plan
– Discusses motorcycles and barrier design
– Links to Task Force 13 Guide to Standardized
Highway Barriers and FHWA Acceptance Letters
– New W-beam systems, including MGS and the
proprietary 31-inch systems
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2010 SCOD Columbia, SC
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Typ. W-Beam
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2010 SCOD Columbia, SC
MGS
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5:1 Flare Rate
- 65.1 mph
- 4440 lbs
- 36.8 deg
I.S. = 226 kip-ft
Eff. Flare Rate = 4.0:1
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2010 SCOD Columbia,
at 2000P/25 deg/100
kph SC
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LSC-1
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2010 SCOD Columbia, SC
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Culvert Opening Protection
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2010 SCOD Columbia, SC
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RDG 2010 – Highlights of Changes

Chapter 5 – Continued
– Zone of Intrusion concept
– Revised discussion of guardrail behind curbs
– Runout lengths reduced for barrier design
– Guardrail posts in rock or mow strips
– Upgrading existing systems revised
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2010 SCOD Columbia, SC
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Zone of Intrusion
F:\Roadside Safety\Median
Barrier\Semi over CMB
in Dallas on north
tollway.wmv
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2010 SCOD Columbia, SC
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Zone of Intrusion
When practical, accommodation of ZOI
should be considered on new and
reconstruction projects.
 Generally, narrowing of the roadway
(including shoulders) is not recommended
on existing high speed facilities to
accommodate this additional distance
behind the barrier.

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2010 SCOD Columbia, SC
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LRFD Bridge Pier Protection
Requirements
Piers within 30 ft. (9m) of traveled way
– Design for load equivalent to large truck impact
OR
– Shield with barrier to prevent impact by truck
 <10 Feet – Use 54” (1370 mm) high rigid barrier
 >10 ft. (3m) – Use 42” (1070mm) high rigid barrier
 RDG recommends LON based on 15 departure angle,
then transition to appropriate barrier for facility.
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2010 SCOD Columbia, SC
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LRFD Barrier Offset Guidelines

Need national risk-based warrants
for this criteria that consider:
 AADT,
 Route Classification,
 Bridge Type,
 Site Location Details,
 Risk vs Benefit of Tall Barrier per LRFD
Criteria
 Length of barrier for LRFD criteria, etc

More research needed
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2010 SCOD Columbia, SC
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RDG 2010 – Highlights of Changes

Chapter 7 – Bridge Railings
– Discusses MASH and LRFD
– Incorporates “Protective Screening at
Overpasses”
– References Task Force 13 Bridge Rail Guide
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2010 SCOD Columbia, SC
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RDG 2010 – Highlights of Changes

Chapter 8 – End Terminals
– Discusses grading in advance of and behind
terminals
– Lists numerous new terminals and crash
cushions
– Includes a table of Comparative Maintenance
Requirements
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2010 SCOD Columbia, SC
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RDG 2010 – Highlights of Changes

Chapter 9 – Work Zone Devices
– Generic and Proprietary PCB designs
enumerated
– Reduce deflection / pinned barriers
– Water filled barriers v longitudinal
channelizers
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2010 SCOD Columbia, SC
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RDG 2010 – Highlights of Changes

Chapter 10 – Roadside Safety in Urban or
Restricted Environments
– Describes an urban clear zone of 4 feet
minimum, 6 feet desirable
– Urban control zone concept: keep obstacles
away from intersections, driveways, speed
change lanes
– Emphasizes 1.5 foot min lateral offset to
obstructions is not a clear zone
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2010 SCOD Columbia, SC
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RDG 2010 – Highlights of Changes

Chapter 11 - Mailboxes
– Vandal proof mailboxes
– Secure, locked mailboxes
– Lightweight plastic designs
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2010 SCOD Columbia, SC
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RDG 2010 – Highlights of Changes

Chapter 12 - ROADSIDE SAFETY ON LOWVOLUME ROADS AND STREETS
– New chapter to RDG
– Low cost strategies: SIGNING, MARKING,
AND DELINEATION
– Clear zone
– Roadside hardware
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2010 SCOD Columbia, SC
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RDG Schedule

Schedule for Publication
– Final balloting by TCRS Summer 2010
– Ballot to SCOD Summer/Fall 2010
– TCRS to address SCOD ballot comments by
Fall/Winter
– Ballot to SCOH by Spring 2011
– Publish Update Summer 2011
29
For additional information please contact:
Rod Lacy
Kansas Department of Transportation
785-296-3901
[email protected]
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2010 SCOD Columbia, SC
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