New Guides from Austroads Consortium

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New Guides from Austroads Consortium
23 November 20043rd November 2009
23 November 2004James Hughes - National Design
Engineer Highways Network
Operations
A New Zealand perspective
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The Consortium members

• Representatives from
• NZ Transport Agency
• New South Wales
• Victoria
• Queensland
• Western Australia
• South Australia
• Tasmania
• Northern Territory
• Capital territory
• DOT Regional Services
• Local Government Association

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Guides, Codes and Standards

• Barbossa
• First, your return to shore was not part of our
  negotiations nor our agreement so I must do
  nothing. And secondly, you must be a pirate for
  the pirate's code to apply and you're not. And
  thirdly, the code is more what you'd call
  "guidelines" than actual rules. Welcome aboard
  the Black Pearl, Miss Turner

Pirates of the Caribbean The Curse of the Black
Pearl
Elizabeth Wait! You have to take me to shore.
According to the Code of the Order of the
Brethren...
4
The Guides Positioning (i)

• Augment SHGDM and GTEP series
• Rationalised
• Updated information
• Review of best practice and research
• Refer to Jurisdictional variations
• MOTSAM
• Superelevation application

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The Guides Positioning (ii)

• Replace SHGDM and GTEP Series
• Rationalised
• Updated information
• Review of best practice and research
• Refer to Jurisdictional variations
• MOTSAM
• Require Jurisdictional Supplements
• Phasing out of SHGDM

FEEDBACK
6
The Guides Audiences

• Policy makers and Strategic Planners
• Road Transport Planning
• Road Safety
• Traffic Management
• Project Managers
• Project Delivery
• Project Evaluation
• Design Practitioners
• Road Design
• Bridge technology
• Road Tunnels
• Pavement Technology
• Network and Asset managers
• Asset Management

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Where can I get a copy?

• Guides are available in hardcopy and PDF format
  from the Austroads website
• Guides are free (in PDF format) to road agencies
  including councils in Australia and New Zealand.
• www.onlinepublications.austroads.com.au

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Providing for a Safe System

• designing, constructing and maintaining a
• road system (roads, vehicles and operating
• requirements) so that forces on the human
• body generated in crashes are generally less
• than those resulting in fatal or debilitating
• injury..

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Providing for a Safe System
Speeds
High risk drivers
Safer speeds
Walking and cycling
Light vehicles
Roads
?
Safer roads and roadsides
Safer vehicles
Roadsides
Older users
Heavy vehicles
Fatigue
Restraints
Safer use
Motorcycles
Distraction
Alcohol and drugs
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Providing for a Safe System
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The Guides Summary
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The Guides Road Design

• Part 1 Introduction to Road Design
• Part 2 Design Considerations
• Part 3 Geometric Design
• Part 4 Intersections and Crossings
• Part 4A Unsignalised and Signalised
  Intersections
• Part 4B Roundabouts
• Part 4C Interchanges
• Part 5 Drainage Design
• Part 6 Roadside Design, Safety and Barriers
• Part 6A Pedestrian and Cyclist Paths
• Part 6B Roadside Environment
• Part 7 Geotechnical Investigation Design
• Part 8 Process and Documentation

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The Guide to Road Design

• Largely an amalgamation replacing
• Guides to Engineering Practice (GTEP)
• Geometric Design of Rural Roads
• Geometric Design of Major Urban Roads
• Geometric Design for Trucks
• Grade Separated Interchanges

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The Guide to Road Design

• Project rather than discipline focus
• Advice in the appropriate place for treatment of
• Cyclists
• Motorcyclists
• Pedestrians
• Issues for policy makers and strategists
• Where has it gone guide!

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The Guide to Road Design

• Key Features
• Incorporates the Safe System Approach
• Introduces Design Domains
• Adopts new Sight Distance model
• Issues
• Superelevation Calculations
• Turn Warrants

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Format of each guide

• Body contains the bulk of the design criteria
• Appendices contain additional design criteria
  examples
• Commentaries contain supporting material /
  background information
• Material in one place only i.e. not duplicated
  between parts or between other series
• High level of cross-referencing used

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The Guide to Road Design

• Part 1 Introduction to Road Design
• Part 2 Design Considerations
• Part 3 Geometric Design
• Part 4 Intersections and Crossings
• Part 4A Unsignalised and Signalised
  Intersections
• Part 4B Roundabouts
• Part 4C Interchanges
• Part 5 Drainage Design
• Part 6 Roadside Design, Safety and Barriers
• Part 6A Pedestrian and Cyclist Paths
• Part 6B Roadside Environment
• Part 7 Geotechnical Investigation and Design
• Part 8 Process and Documentation

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Safe System

• Safe System approach
• Highlights the importance of consistency
• Focus on vulnerability
• Importance of readability and predictability
• Forgiving roadside

QED?

• In NZ
• Work hard on Consistency, Readability and
• Predictability

R
C
a
P
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Design Domain (i)

• Normal Design Domain (NDD)
• An acceptable range rather than a single value
• Provide flexibility for context sensitive designs
• Manifests itself primarily wrt Sight Distances
• In NZ
• Onus on designers to justify their decisions
• Should simplify the approval process
• Vigilant Clients!

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Design Domain (ii)

• Extended Design Domain (EDD)
• Provision for values outside the acceptable range
• Encourages extension of engineering rationale
• Must only be considered when all else is
  favourable
• Only ever one parameter in isolation
• Highly constrained sites
• In NZ
• Onus heavily on designers to justify their
  decisions
• Should improve the approval process
• Informed Clients!

The Decision to use EDD should not be taken
lightly
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Extended Design Domain (EDD)
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EDD Parameters

• Urban/Brownfield Sites
• Lane Widths
• Shoulder Widths
• Sight Distance
• Object height Vertical Curves
• Reaction time SSD, ASD
• Deceleration rate SSD ASD
• Clear Zones?
• Anything else?

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New Sight Distance Model (i)

• Based on research findings
• Less conservative values
• Still a high level of safety
• Acceptable reaction times
• 1.5, 2.0 and 2.5 seconds
• Range of deceleration rates
• 0.26g, 0.36g and 0.46g

• Revised Drivers eye- height
• 1.1m for Cars
• 2.4m for trucks
• Revised target heights
• 1.2m for Car roof
• 0.8m for Brake-lights

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The Guide to Road Design

• Part 1 Introduction to Road Design
• Part 2 Design Considerations
• Part 3 Geometric Design
• Part 4 Intersections and Crossings
• Part 4A Unsignalised and Signalised
  Intersections
• Part 4B Roundabouts
• Part 4C Interchanges
• Part 5 Drainage Design
• Part 6 Roadside Design, Safety and Barriers
• Part 6A Pedestrian and Cyclist Paths
• Part 6B Roadside Environment
• Part 7 Geotechnical Investigation and Design
• Part 8 Process and Documentation

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New Sight Distance Model (ii)

• Broad guidance on application
• Need clear advice about hierarchy
• Road classification
• Parameters
• Trucks critical for horizontal widening
• Appropriate for operating speed

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New Sight Distance Model (iii)

• Effect of eye height change from 1.05 -gt 1.1m
• Small percentage change
• Round values up

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Significant Parameters

• Horizontal and vertical geometry
• Removal of Unit Chord
• New Sight Distance model
• Road Cross-section
• Superelevation as per SHGDM

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The Guide to Road Design

• Part 1 Introduction to Road Design
• Part 2 Design Considerations
• Part 3 Geometric Design
• Part 4 Intersections and Crossings
• Part 4A Unsignalised and Signalised
  Intersections
• Part 4B Roundabouts
• Part 4C Interchanges
• Part 5 Drainage Design
• Part 6 Roadside Design, Safety and Barriers
• Part 6A Pedestrian and Cyclist Paths
• Part 6B Roadside Environment
• Part 7 Geotechnical Investigation and Design
• Part 8 Process and Documentation

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Sight distance at Intersections

• Still require
• approach sight distance (ASD)
• safe intersection sight distance (SISD)
• minimum gap sight distance (MGSD)
• Guide no longer contains entering sight distance
  ESD
• Distances so large they were impracticable
• No jurisdictions could quote instances where it
  had been used as a design requirement
• NDD values in guide are minimum should always
  provide better if there are no implications of
  doing so.

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Sight distance at intersections

• ASD - approach sight distance
• SISD - safe intersection sight distance
• MGSD - minimum gap sight distance

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Development of new Right-Turn warrants

• Identify the location at which the benefits of
  providing a higher-level treatment (the reduction
  in estimated accident costs) are made equal to a
  proportion of the additional construction costs
  for
• High speed roads gt100km/h
• Low and intermediate speed roads lt100km/h.

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Development of new Right-Turn warrants

• BCR 1
• Design life 10 years
• Estimated construction costs for intersections on
  new roads (i.e. greenfield sites) based on a
  number of assumptions
• Accident rates from Arndt (2004)
• Cost per accident 38,974.

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Comparison of existing and new Right-Turn warrants
High Speed
Low Intermediate Speed
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New Right-Turn warrants NZ
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Roundabout Design

• No section on performance
• Refer to the Austroads Guide to Traffic
  Management Part 3 Traffic Studies and Analysis
• Table provided for criterion 2 sight distance
• Context specific and speed sensitive
• Requirement for truck stopping sight distance
• New design procedure
• New design tables for central island radius and
  entry radius
• Deflection requirement removed
• Information on treatments for cyclists

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Speed control at roundabouts (i)

• Attributes of the new method
• Be comprehensive as possible in minimising
  accident types (including using the entry path to
  control speed)
• Require little design effort
• Require little subjectivity in drawing of any
  vehicle paths
• The new method sets absolute and desirable values
  for
• maximum entry path radii
• minimum central island radii
• Is based on the models in QDMR (2006).

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Speed control at roundabouts (ii)

• Absolute limits
• Identified combinations of minimum central island
  radii and maximum entry path curvature that meet
  all of the parameter limits in the Queensland
  model
• Desirable limits
• Identified the combinations that avoid corner
  kerb radii and allow sufficient splitter island
  size for pedestrians, whilst still meeting the
  parameter limits.

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Entry treatment

• A straight approach and a single entry curve
• excessive decrease in speed at start of entry
  curves
• potential for high single vehicle crash rate
• Important to treat these situations to alert
  drivers and/or more gradually reduce vehicle
  speeds
• Careful consideration of superelevation

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Pedestrians and Bicycle lanes
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Design of Interchanges

• Need to refer to
• Broad planning requirements
• Guide to Traffic Management
• particularly GTM Part 6 Intersections,
  Interchanges and Crossings
• Guide to Traffic Management Part 3 Traffic
  Studies and Analysis
• Highway Capacity Manual TRB (2000)
• Guide to Road Design
• all parts
• particularly GRD Part 3 Geometric Design

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Principles

• Interchange Elements
• carriageway/s of the major road
• carriageway/s of the minor road
• ramps
• diverge and merge areas associated with the major
  road
• ramp terminals at the minor road (e.g.
  unsignalised or signalised intersections or
  roundabouts)
• shared paths (pedestrians and cyclists)
• Interchange uniformity and spacing

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Service and System Interchanges
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Ramp Design

• Number of Lanes
• Can depend on level of service required, truck
  speed, length
• incorporate future ramp metering
• Guide - two lane ramp required where
• ramp volume and LOS requires it
• truck speeds at nose likely to be lt 50 km/h
• Ramp length gt 600 m
• Entry/Exit layout as per MOTSAM III

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Ramp Design - Cyclists

• ON

• OFF

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The Guide to Road Design

• Part 1 Introduction to Road Design
• Part 2 Design Considerations
• Part 3 Geometric Design
• Part 4 Intersections and Crossings
• Part 4A Unsignalised and Signalised
  Intersections
• Part 4B Roundabouts
• Part 4C Interchanges
• Part 5 Drainage Design
• Part 6 Roadside Design, Safety and Barriers
• Part 6A Pedestrian and Cyclist Paths
• Part 6B Roadside Environment
• Part 7 Geotechnical Investigation and Design
• Part 8 Process and Documentation

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Roadside Design, Safety Barriers

• Hazard Corridor
• Risk assessment
• Identify and mitigate
• More subjective guidelines
• RTA (NSW)
• WA (Perth)

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Roadside Design, Safety Barriers

• Environmental focus
• Context sensitivity
• Variable Clear-zone (AASHTO)
• Practical advice
• Simplified curve correction
• Errant Vehicles
• Steep gradients

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Pedestrian and Cyclist Paths

• Off-road facilities
• Location
• Security
• Amenity
• Geometric design considerations
• Shared or segregated
• Intersections
• Terminals
• Structures

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Roadside Environment

• Environmental
• Storm-water Control
• Fauna management
• Noise control
• Amenity
• Visual/Landscaping
• Rest Facilities

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Roadside Environment

• Infrastructure
• Furniture
• Lighting
• Emergency/Help Telephones
• Off-Street Parking
• Utilities
• NZUAG Code of Practice

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Information Board

• www.nzta.govt.nz
• www.austroads.com.au
• www.onlinepublications.austroads.com.au
• james.hughes_at_nzta.govt.nz