Traffic Barrier Guidelines Barrier Warrant Analysis Hands-On Workshop III July 2013

Traffic Barrier Guidelines Barrier Warrant Analysis

Hands-On Workshop III July 2013

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References

AASHTO Roadside Design Guide, 4th Edition-2011

Clear Zone, Chapter 3 Location of Barriers, Chapter 5 Barrier Length & End Treatment,

Chapter 5 Benefit/Cost Analysis

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Traffic Barrier Guidelines

How Many People Brought a Copy?3

• BWA Process• Usage Guide

Barrier Warrant Analysis Procedure

Traffic Barrier GuidelinesSection 4.0

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Barrier Warrant Analysis Procedure1. Identify Potential Obstacles2. Name Obstacles3. Prepare/Present Exhibit (Concept Meeting)

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Barrier Warrant Analysis Procedure1. Identify Potential Obstacles.2. Name Obstacles.3. Prepare/Present Exhibit.4. Each AOC shall be analyzed separately.

a. Establish EOTW

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a. Establish Edge of Traveled Way

EOP 1’ outside of the EOTW

EOTW = EOP

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a. Establish EOTWb. Design Speed (Speed Profile for ramps, etc.)

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a. Establish EOTWb. Design Speedc. Design ADT

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a. Establish EOTWb. Design Speedc. Design ADTd. Length of Runout

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c. Length of Runout

L2

Figure 5-39. Approach Barrier Layout Variables

LR

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c. Length of Runout

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a. Establish EOTWb. Design Speedc. Design ADTd. Length of Runoute. Shy Line Offset

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d. Shy Line Offset

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a. Establish EOTWb. Design Speedc. Design ADTd. Length of Runoute. Shy Line Offsetf. Foreslope/Backslope

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f. Foreslope/Backslope

Foreslope

Backslope

ForeslopesWithin clear zone 1:6 (desirable) 1:4 (maximum)Elsewhere1:4 (desirable)1:3 (maximum)

Backslopes 1:4 (desirable)1:2.5 (maximum)

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Barrier Warrant Analysis Procedure (cont.)

g. Clear Zone

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Clear Zone:The unobstructed, traversable area provided beyond the edge of through traveled way for the recovery of errant vehicles.

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Clear Zone Distances (Feet) From Edge of Traveled Way (RDG Table 3-1)

Use highest value in range19

Clear Zone Distances (Feet) From Edge of Traveled Way (Table 3-1)

Use highest value in range20

Barrier Warrant Analysis Procedure (cont.)g. Clear Zoneh. Clear Zone Adjustment

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h. Clear Zone Adjustment

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Barrier Warrant Analysis Procedure (cont.)g. Clear Zoneh. Clear Zone Adjustmenti. Lateral Extent of the Area of Concern (LA)

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i. Lateral Extent of the Area of Concern

L2


LA

L3

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Barrier Warrant Analysis Procedure (cont.)g. Clear Zoneh. Clear Zone Adjustmenti. Lateral Extent of the Area of Concernj. Warrant Analysis Level

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j. Warrant Analysis Level

Decide Warrant Analysis Level Level 1 Level 2 Level 3

Level 0

UseFlowchart For Existing

Obstaclesor

Flowchart for Proposed Obstacles

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Flowchart for Analysis of Existing Obstacles (Figure 5.5a)

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Flowchart for Analysis of Proposed Obstacles (Figure 5.5b)

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Warrant Analysis Level (Article 5.5)

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Level 1 Analysis (Article 5.5.1) Level 1 – Existing AOC’s that are traversable

elements or can easily be made traversable elements such as: Existing ground mounted signs, and existing

drainage items Existing ground mounted light poles and

electrical handholes

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Traversable Element

RDG-Figure 4-1. Breakaway SupportStub Height Measurements

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4 in.

5 ft.

(Steel or Wood)

Traversable Element

4’

1:6(V:H)

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Level 1 Analysis (Article 5.5.1) Level 1 – Proposed AOC’s that are

traversable elements: Proposed Ground-Mounted Signs Proposed Light Poles Proposed Drainage Items (culvert and pipe ends

84” or less in vertical opening)

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Level 1 Analysis-Sample Table

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Breakaway Sign PostsAn important feature of this breakaway sign system is the ability of its post support to swing up and out of the way when it is struck by an errant vehicle.

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Safety End Treatment-Steel GrateHeadwall and storm sewer outlets shall be provided with appropriate safety end treatment per Standard Drawings – Section B.

Direction of Traffic

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Roadway Lighting

Steel Helix Foundation

Needs to be a Traversable

Element

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Level 2 Analysis (Article 5.5.2)

When shielding is required and barrier length of need must be determined.

Cantilever sign post

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Shielding- Definition

Shielding—The introduction of a barrier or crash cushion between the vehicle and an obstacle or area of concern to reduce the severity of impacts of errant vehicles.

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Level 2 Analysis

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Median Emergency Turnaround


This analysis is performed for:

EXISTING/PROPOSED OBSTACLES when there are no feasible alternatives for eliminating, or reducing the impact severity of the obstacle.

PROPOSED OBSTACLES for an Alternative in a Level 3 Analysis. The length of barrier and type of terminals has to be determined for each Alternative that involves shielding of the obstacle.

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The evaluation of two or more feasible alternatives for;

Removing Relocating Reducing the impact severity of Shielding the obstacle

This is part of the design process

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Level 3 AnalysisDetermination of Alternatives (Article 5.6.1) If a Level 3 analysis is warranted, then the designer

needs to use engineering judgment when selecting the alternatives to evaluate.

Only consider alternatives that are feasible. Cannot analyze an alternative that leaves an

obstacle unshielded in the clear zone.

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When considering relocation of a fixed object, in addition to changing the offset from the EOTW, the designer should consider relocation upstream or downstream.

Alternatives for sign truss span lengths or cantilever arm lengths shall not exceed the maximums shown on the Tollway Standard Drawings.

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Additional guidance for determination of alternatives for Level 3 Analysis The following values shall be exceeded when

relocating an obstacle onto a non-recoverable, thus undefined clear zone, foreslope or when considering leaving an obstacle unshielded on a non-recoverable foreslope:

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Roadside Safety Analysis Program (RSAP)

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Roadside Safety Analysis Program (RSAP)

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http://www.trb.org/Main/Blurbs/152743.aspx

Level 3 Analysis

Overhead sign to span roadway with barrier

Overhead sign to span beyond clear zone with no barrier

This is most common Level 3

obstacle

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Level 0 Table Requirements(Articles 5.5 and 6.13.8) Potential AOCs not analyzed with a Level 1, 2, or 3

Analysis shall be included in a Level 0 Table. This table should include all potential AOCs that

were initially identified in the process, but were determined to be well outside of the clear zone or existing obstacles physically removed from the project and, therefore required no analysis.

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Barrier Warrant Analysis Procedure (cont.)g. Clear Zoneh. Clear Zone Adjustmenti. Lateral Extent of the Area of Concernj. Warrant Analysis Levelk. Lateral Offset of Barrier (L2)

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k. Lateral Offset of Barrier

L2


L2

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k. Lateral Offset of Barrier2’- 2 ¾” With Type G-3 Gutter

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k. Lateral Offset of Barrier1’-0” w/o

Gutter

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Barrier Warrant Analysis Procedure (cont.)g. Foreslope/Backslopeh. Clear Zonei. Clear Zone Adjustmentj. Warrant Analysis Levelk. Lateral Offset of Barrier l. Upstream End of Guardrail

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l. Upstream End of Guardrail

Y = L2 + 0.75’

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L2


X= (LA – Y) / (LA / LR )LA

LR

LA - Y X

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Length of Need (LON)

L2


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LON = X + LAOC

LAOC


< LR

LA

L2

Y

X

Figure 5-48. Example of Barrier Design for Fixed Object on Horizontal Curve

Graphical Solution for “X”

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L2


Point of Need

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Barrier Warrant Analysis Procedure (cont.)g. Clear Zoneh. Clear Zone Adjustmenti. Lateral Extent of the Area of Concernj. Warrant Analysis Levelk. Lateral Offset of Barrierl. Upstream End of Guardrailm. Upstream End of Barrier Wall

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m. Upstream End of Barrier Wall

A = Suggested maximum flare rate for rigid barrier system.

B = Suggested maximum flare rate for semi-rigid barrier system.

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Barrier Warrant Analysis Procedure (cont.)g. Clear Zoneh. Clear Zone Adjustmenti. Lateral Extent of the Area of Concernj. Warrant Analysis Levelk. Lateral Offset of Barrierl. Upstream End of Guardrailm. Upstream End of Barrier Walln. Downstream Terminal

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n. Downstream Terminals

Traffic Barrier Terminal Type T2

Traffic Barrier Terminal Type T6 (pictured) or Type T6B

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Barrier Warrant Analysis Procedure (cont.)g. Clear Zoneh. Clear Zone Adjustmenti. Lateral Extent of the Area of Concernj. Warrant Analysis Levelk. Lateral Offset of Barrierl. Upstream End of Guardrailm. Upstream End of Barrier Walln. Downstream Terminalo. Barrier Obstacle

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Barrier Warrant Analysis Procedure (cont.)g. Clear Zoneh. Clear Zone Adjustmenti. Lateral Extent of the Area of Concernj. Warrant Analysis Levelk. Lateral Offset of Barrierl. Upstream End of Guardrailm. Upstream End of Barrier Walln. Downstream Terminalo. Barrier Obstaclep. Compare existing length to proposed

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Barrier Warrant Analysis Procedure (cont.)g. Clear Zoneh. Clear Zone Adjustmenti. Lateral Extent of the Area of Concernj. Warrant Analysis Levelk. Lateral Offset of Barrierl. Upstream End of Guardrailm. Upstream End of Barrier Walln. Downstream Terminalo. Barrier Obstaclep. Compare existing length to proposedq. Prepare warrant text and exhibits

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Presentation of BarrierWarrant Analysis

Section 6.0

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Presentation of Barrier Warrant Analyses

Samples Speed Profile Location Plan Level 1 Table Data Sheet Calculation sheet Site Plan

RSAP Feature Sketch

Level 0 Table

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Presentation of Barrier Warrant Analysis Checklists

Cover Sheet Table of Contents Disposition Location Plan Data Sheet Calculation Sheet Site Plan

Summary Site Plan Cross Sections Level 0 Table Level 1 Analysis Level 2 Analysis Level 3 Analysis

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Barrier Warrant Submittal Check List

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Highlights of the Process

Each AOC analyzed separately If several AOC’s are in close proximity, then

look for overlapping LON’s and gaps. Create Summary Site Plan Create AOC Table Calculations for overlaps / gaps (As Necessary)

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AOC’s in Close Proximity

AOC #1 AOC #2 AOC #3 AOC #4

LON #1

LON #2

LON #3 LON #4

Overlap Overlap

Gap < 100’

Total LON

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Hot List-Common Mistakes Lack of DSE QC/QA Barrier Warrant Analysis is a Stand Alone

Document (Include Applicable Drawings) Site Plans Missing Information

Traffic Barrier Terminals Guardrail (By Type & Post Length) Recovery Area Label all Obstacles

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Common Mistakes (continued) Checklist needs to be submitted and complete Disposition of Comments & Comment Resolution Drainage structures placed within the limits of

traffic barrier terminals Including items in the Level 1 table that are not

Level 1 items Not addressing the barrier clearance distance Intermixing Traffic Barrier Terminal (TBT) Type T6

and TBT Type T6B

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Common Mistakes (continued) Not replacing gutter on rehabilitation contracts

when relocating Traffic Barrier Terminals Calculation of Length of Need on the outside of

horizontal curves (Graphical Solution required) Determination of Feasible Alternatives Locating the beginning and ending of slope

obstacles Evaluating potential obstacles along ramps, C-D

roads, or auxiliary lanes

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Common Mistakes (continued) Analysis of closely spaced or overlapping potential

obstacles Preparation of speed profiles Minimum Length of free standing guardrail Identification of all potential obstacles Cross sections for LAOC & LR

Repeating information in the BWA

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Submittal Schedule (Section 7.0)

Barrier Warrant Analysis is part of the Design Process.

Barrier Warrants are not considered final until there are no further review comments on the final submittal. (Article 7.6)

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Concept Meeting (Article 7.1)The general goals of the meeting are to:

Provide an overview of the project limits, scope of work, and any omissions

Summarize the overall project schedule Discuss potential AOC’s and barrier warrant

analysis methodology Present unique project issues Identify locations that are good candidates to be

included in the preliminary submittal.

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Concept Meeting (cont.) ID potential obstacles before clear zone is determined.

DSE to prepare an exhibit and present potential obstacles at a meeting to be held 1-2 weeks before Concept Plan submittal.

Aerial or TOPO background exhibit showing all potential obstacles.

Concept Plan submittal should only include the Meeting Minutes.

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Preliminary Submittal (Article 7.2) Barrier Warrant Analysis shall be submitted with

the Preliminary Plans. Submit a minimum of five sample locations

At least two Level 2 At least two Level 3 with RSAP output and feature sketch It is recommended that Designer choose locations that

may require more review cycles, are more complex or require extra coordination.

Submit one page each of the Level 1 and Level 0 Tables (at least 4 AOC’s each)

Submit Completed Checklist.

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Pre-Final Submittal (Article 7.3) Barrier Warrant Analysis shall be submitted with

the Pre-Final Plans. Similar to Pre-Final Plans, the Pre-Final Barrier

Warrant shall be considered 100% complete. All comments on preliminary submittal addressed

and a disposition provided. Submit completed checklist. All above materials shall be submitted through the

Tollway’s web-based project management system and in hard copy format.

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Final Submittal (Article 7.4) DSE Final Barrier Warrant shall match the DSE

plans submitted for advertisement. Final Barrier Warrant Analysis should be complete

at the Final Plan Check. All previous review comments addressed and a

disposition provided. Submit completed checklist.

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Amendment Process (Article 7.7)What initiated

change to design?

Who initiated change?

Who completes Amendment to

BWA?

In addition to GEC, who reviews BWA Amendment?

Field Change CM or Contractor DSE CM

Value Engineering

Proposal (VEP) Contractor Contractor’s

Designer DSE & CM

Performance Based Design

(PBD)Contractor Contractor’s

Designer DSE & CM

Tollway Directive Tollway DSE CM

Record Drawings

FieldConditions

Final Amended Barrier Warrant

3 Components must be equal

==

=

=

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Questions?

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LUNCH HOUR

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Traffic Barrier Guidelines Barrier Warrant Analysis Hands-On Workshop III July 2013

Documents

Transcript of Traffic Barrier Guidelines Barrier Warrant Analysis Hands-On Workshop III July 2013