Data Collection Technologies for Road Management

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Data Collection Technologies for Road Management

• Brown Bag Lunch Presentation
• 4 May 2005
• Christopher R. Bennett
• EASTR

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Introduction
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Project Objectives

• Give an overview of technologies available to
  collect data on
• Pavements
• Bridges
• Traffic Volume and Weight
• Provide information to managers to help
• Establish an appropriate data collection program
• Procure appropriate equipment

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Project Details

• Funded by TRISP
• Group Effort
• C.R. Bennett (World Bank)
• H. de Solminihac/A. Chamorro (Catholic University
  Chile) - Pavements
• G. Flintsch/C. Chen (Virginia Tech) - Bridges and
  Traffic
• Conducted research and user surveys
• Outputs
• Report
• www.road-management.info

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Road Management Data
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Categories of Data

• Inventory
• Physical elements of system
• Do not change markedly over time
• Typically measured in one off exercise and
  updated

• Condition
• Change over time
• Require regular (or irregular) monitoring

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What to Collect?

• Foundational question
• Decision often based on
• Wish list (nice to have)
• Existing or historical data collection processes
• Can lead to data collection becoming an end in
  itself
• Excessive or inefficient data collection could
  compromise project

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Recommended Approach

• Collect only the data you need
• Collect data to the lowest level of detail
  sufficient to make an appropriate decision
• Collect data only when they are needed
• Use pilot studies to test the appropriateness of
  the approach

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Information Quality Levels
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Survey Frequency

• Inventory Data
• One off exercise
• Updated/verified 5 years
• Pavement Condition Data
• Main roads 1-2 years
• Minor roads 2-5 years
• Bridge Condition Data
• Regular surveys 1-2 years
• Intensive surveys 5 years
• Traffic Data
• Permanent count stations (24/7/365)
• Short-term count stations ( 1 - 7 days)

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Location Referencing
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The Most Important Issue

• Unless properly referenced, data will be of
  limited use
• Two elements
• The location
• The address used to identify the location
• Three components
• Identification of a known point (eg km stone)
• Direction (ie increasing/decreasing)
• Distance measurement (ie displacement/ offset)

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One Location - Many Addresses
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Linear Referencing

• Most common
• Different methods
• Kilometre point (e.g., 9.29)
• Kilometre post (e.g., 9.29 with equations)
• Reference point (e.g., xx 0.29)
• Reference post (e.g., xx 0.29)

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Spatial Referencing

• Latitude/Longitude
• Usually measured with GPS
• Accuracy typically 95 /- 10 m
• Improved through differential correction or
  post-processing
• Survey issues will typically give accuracy /- 1
  m
• Recorded in WGS84 datum and so usually needs to
  be converted to local co-ordinate system

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Example of Projection Problem
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GPS Topological Corrections
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Pavement Data Collection
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Pavement Data Framework
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Measurement Equipment Types
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Multi-function Systems

• Measure multiple attributes in a single pass
• Most cost effective and reduces location
  referencing issues
• Two groups
• Portable systems installed in any vehicle
• Dedicated systems custom instrumented vehicle
• Portable usually cheaper and more sustainable but
  sophisticated measurements require dedicated
  vehicle

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Location Referencing

• Digital DMI (lt 1 k)
• GPS (lt 1 10 k)
• GPS with Inertial System (lt 2 - 15 k)

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Video Logging
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Geometry

• Combine GPS and precision gyroscopes/
  inclinometers (gt 50k)
• Precise 3-D measurements including cross-fall

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Roughness

• Bumpiness of road
• Usually related to servicability but also
  reflects structural deterioration
• Affects VOC, safety, comfort, speed
• Most commonly expressed as IRI
• IRI simulates response of Quarter-car to road
  profile

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Types of Equipment
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Roughness Measurements
Class I
Class III
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Variability Between Class I Instruments
2.5 IRI (m/km) 3.5
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Comparison of Footprints
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Texture

• Measurements focus on microtexture and
  macrotexture
• High speed measurements use lasers
• Expressed as the MPD or SMTD

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Texture Measurements
Macrotexture
Microtexture
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Skid Resistance

• Primarily function of surface texture
• Tire contact with texture creates grip under
  wet conditions
• Speed has impact
• lt 70 km/h microtexture dominates
• gt 70 km/h macrotexture important
• Measured indirectly by operating wet tire on
  pavement
• Often expressed as IFI

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Skid Resistance Measurements
Dynamic
Static
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Structural Capacity

• Destructive techniques
• Coring
• DCP
• Non-destructive techniques
• Deflection measurements

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Deflectometers
Trailer FWD
Vehicle FWD
Portable
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Benkelman Beam
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Ground Penetrating Radar
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Surface Distresses

• Performed manually or with automated equipment
• Includes
• Cracking
• Surface Defects
• Deformations
• Great variation in measures used between
  countries

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Distress Measurements
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Video Distress Analysis
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Current Situation Video Distress

• A number of successful commercial systems
• Some degree of human intervention required
• Systems usually expensive (gt 200 k) and require
  dedicated vehicles with supplemental lighting
• Technology evolving

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Rut Depths

• Measured using discrete sensors
  (ultrasonic/laser) or line
• Data analyzed to simulate rut depth under a
  straight edge
• Systematic under-recording with discrete sensors

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Selecting Equipment

• Used multi-criteria analysis based on survey and
  literature review

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Cost/Performance Matrix
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Traffic Data
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Types of Traffic Equipment

• Generally two components
• Sensor
• Data Logger
• Different technologies for different purposes

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Classifications

• Based on number of axles and axle spacings or
  length
• Different countries have different systems
• Important to be able to set up for local vehicle
  fleet

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Data Produced by Different Sensors
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Examples of Sensors
Inductance Loop
Video Detection
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Manual Counters
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Vehicle Weighing Equipment
Static Plate
Capacitance Pad
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WIM Classifications

• Type I high accuracy data collection systems
  (typically bending plate scale type WIM)
• Type II lower cost data collection systems
  (typically piezoelectric scale type WIM)
• Type III systems for use in a sorting
  application at weigh station entrance ramps
  (bending plate or deep pit load cell type WIM) at
  speeds from 15 to 50 mph
• Type IV low-speed WIM

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Suitability Rankings