framework for assessment of state performance and management of canada’s core public...

Framework for Assessment of State Performance and Management of Canada’s

Core Public Infrastructure (CPI)

Review of State- of- Art

Meeting of the National Round Table on Sustainable InfrastructureMarch 26, 2008, Toronto

Outline

• Background

• Review of performance assessment of CPI

• Knowledge “deficit” in performance assessment

• Approach

Background

• CPI: roads, bridges, transit, water and wastewater systems • Canada’s CPI enable:

– personal mobility– transport of people and goods,– provide safe drinking water – remove wastes– critical to competitiveness of economy and quality of life

• NRC Cross-Canada Tour- Concerns of decision-makers:– aging infrastructure– lack of reliable performance data – ill-defined acceptable minimum levels of performance – few management tools– PSAB 3150 requirements– ineffective communications to decision makers– closing small towns, concerns of northern communities – Environment now on agenda- Sustainability concerns

Decreasing Capacity / Increasing Risk of Failure

Consequences:Health & Safety problems

Economic & Social impactsEnvironmental impact

Background

Inadequate Performance Assessment

+Deterioration of Core Public Infrastructure

Aggressive

Environment

Climate

Change

Aging CPI

Systems

Increasing

Demand

Background

• Life cycle management of CPI = challenging problem

• Optimize allocation of funds for maintenance, rehabilitation & renewal for different CPI systems, given:– large network of CPI systems and components

– CPI systems/components deteriorate with time

– risk of failure increases with time

– lack of reliable data on current and future state of systems

– different assets with different consequences of failure

– limited funds

Challenges

• Safety– load rating, load carrying capacity, reliability index– condition rating, sufficiency rating, appraisal rating, health index

• Serviceability– condition rating– excessive stresses, cracking, deformation, vibration

• Fatigue• Functionality

– condition rating, sufficiency rating– bridge width, vertical/horizontal clearances

Performance Indicators – Bridges

CPI Performance Assessment

Performance Indicators - Bridges


9 to 0 (excellent, very good, …, imminent, failed)

Three general ratings (deck, superstructure and substructure)

• Appraisal ratings

• Sufficiency rating

• SD/FO classification

AASHTO (CoRe elements)

FHWA

Agency Condition rating system

Pontis: 1 to 5 or 1 to 3

Based on detailed element-level inspection (one rating per element type)

Performance Indicator

• Appraisal ratings

• Sufficiency rating

• SD/FO classification

• Health Index (CalTrans)

Canada (e.g. MTO)

Four conditions states : excellent, good, fair and poor

Based on detailed element-level inspection (one rating per element type)

• Bridge condition index (BCI)

• Bridge sufficiency index (BSI)

• Riding comfort index

• Surface distress index

• Structural adequacy index

• Pavement condition index

• International roughness index

• Pavement quality index

Performance Indicators - Roads


Performance Indicators - Roads


Agency Performance Indicators Evaluation

MTO - Ride Condition Rating (RCR)- Pavement distress severity and extent- Pavement condition index (PCI)

0-10 (very poor to excellent)6 severity levels, extent in %

0-100 (poor to excellent)

MTQ -International roughness index (IRI)-Rutting-Pavement cracking

Engineering units (m/km)

Rutting depth

0-100 (poor to excellent)Three ratings : wheel path, transverse cracking and general condition

Alberta -IRI-Surface distress index (SDI)-Structural adequacy index (SAI)-Pavement quality Index (PQI)


FHWA IRI

Present serviceability rating (PSR)


0-5 (subjective rating)

1) Point of Entry (POE) and distribution guidelines

2) Customer Satisfaction

1) Residual Chlorine2) Customer complaints (#) 3) Boil water advisories (# / time)4) …

Hydraulic and Quantity of flow

Water Quality

Failure Criteria Sub Criteria

1) Adequate Pressure2) Fire Fighting Capability3) Emergency Storage4) Adequate Capacity5) Customer Satisfaction

Performance Indicator

1) Flow velocity (max)2) Pressure (min/max) 3) Water age (>1 day) 4) Demand (average, peak) 5) Pumps and storage capacity6) Water consumption/capita7) Low Pressure Complaints …

System Integrity

1) Minimize # and Duration of Interruptions

2) Minimize Response Time3) Minimize Non-Revenue Water4) Maximize Efficiency

1) # of Breaks (normalized)2) # of Leaks (normalized) 3) Amount Non-Revenue Water 4) # Service interruptions5) …


Performance Indicators – Water Systems

1) Effluent guidelines 2) Customer Satisfaction

1) Fecal Coliform Count2) Sewer bypass (#)3) Sewer overflows (#)4) …

Hydraulic and Quantity of flow

Quality Sanitary/Storm

1) Adequate Flow2) Emergency Overflow3) Adequate Capacity4) Customer Satisfaction

1) Flow velocity (min/max) 2) Average daily flow3) Pumps and storage capacity 4) Wastewater produced/capita5) …

System Integrity1) Blockages and backups (#)2) Collapses (#)3) I & I (% or amount)4) Sewage flooding incidents due

to capacity and blockages (#)5) Service interruptions (#)6) Pollution incidents (#,

Severity)7) …

Failure Criteria Sub Criteria Performance Indicator

1) Minimize # and Duration of Interruptions

2) Minimize Response Time3) Maximize Efficiency


Performance Indicators – Wastewater Systems

1) Managing breaks for small diameter distribution systems

2) Transmission Trunks (Large Diameter) use Structural distress indicators (NRC-AwwaRF)

1) WRc Condition Grade (1-5 Defect-based) – Structural (Physical Condition)– Operational (Blockages and

Infiltration)2) NRC Trunk Sewers Guidelines (Defects)3) National Association of Sewer Service

Contractors - NASSCO (Simplified WRc)4) North American Association of Pipeline

Inspectors – NAAPI (Simplified WRc)

Water Sanitary and Storm Water


Performance Indicators – Water & Wastewater Systems

• State-of-art deterioration prediction models are based on Markov chain models :

– qualitative prediction of future performance based on ratings

– modeling of cumulative damage only – No “shock” modeling

– assumption of constant rate of deterioration - Not realistic at all !

– no information on residual capacity and safety

– predicted service life is a rough approximation

– ‘true” condition can be seriously overestimated – disaster!

– examples of decision support systems: “Pontis”, “Bridgit”, etc.

Deterioration Prediction Models


• Same bridges rated by different inspectors :– up to 5 rating points difference! (FHWA 2000) – unacceptable for such critical structures!– predicted remaining life is arbitrary and may lead to unsafe

estimates- disasters (loss of life, injuries, economic impacts, etc.)

Reliability of Performance Indicators- Examples

• Same bridge can be rated by 3 different inspectors as either:– Serious condition – Probability of collapse could be 0.01– Fair condition - Probability of collapse could be 0.05– Critical condition - Probability of collapse could be 0.1

Unacceptable for safety-critical systems


Reliability of Performance Indicators- Examples


• I35 bridge superstructure:

– bridge opened to traffic in 1967

– rated “Poor” not “Critical”

– scheduled for reconstruction in 2020-25– estimated Remaining Life 12-15 years

Condition Rating

4

2

0

3

Poor

Serious

Critical

Imminent failure

Failed

1

Probability of failure

?

?

?

1 ?

? –bridge collapsed 2 years after evaluation !

• Current performance assessment is mainly qualitative

• Focus on material distresses instead of system distresses

• Based on “visual” inspection + some non-destructive techniques

– mapping observed material distresses to subjective rating scales

• Arbitrary definition of minimum performance or failure criteria

• No differentiation between safety-critical and secondary systems

• Limited or no quantitative data on:

– residual capacity, safety

– probability of failure and risk of failure

– remaining life

Summary


“Knowledge Deficit” in CPI Performance Assessment

Time (years)

Per

form

ance

Life cycle

Residual life

Limit state/ acceptable minimum performance

Service life 1

Cumulative damage “wear & tear”

Service life 2

Repair/Rehab/Replace

Random shock- induced damage

Service life 3

Quantitative Measures of CPI Performance - Examples

LoadLoad

Capacity Initial capacity

Time-decreasing capacity

Time

Time-varying probability of failure


• Performance= Capacity – Load• Performance= Capacity / Load• Performance= Probability that Capacity is higher than Load

• Develop rational and objective acceptable minimum levels of performance or limit states considering:

– type of CPI system and component

– consequences of failure/ importance/ criticality of CPI system: e.g. loss of life, health/ injury risks, property loss, environmental impact

– type of failure mode: ductile / progressive or brittle / sudden

– design life of CPI system/ component

Acceptable Minimum Levels of Performance


• Risk of failure enables decision makers to :

– identify critical / high priority components of CPI

– Integrate management of different CPI systems

Quantifying Risk of Failure of CPI

“Knowledge Deficit” in CPI Performance

Assessment

CPI ProjectManagement

CPI Network Management

Integrated CPI Management

• Develop approaches to assess risk of failure of CPI systems:

Risk of failure = Probability of Failure X Consequences of failure

• Build on existing knowledge and best practices• Advance state of knowledge using sound scientific and

engineering approaches and develop: – reliable and practical performance assessment of CPI systems– objective minimum performance levels– “unified” or “model” CPI performance indicators and measures

• Promote adoption and implementation of developed approaches for CPI performance assessment and management

Approach

• NRC and NRTSI will collaborate on research projects:– Phase 1: Development of a framework for assessment of state,

performance and management of CPI

– Phase 2: Development of approaches and tools for performance assessment and management of CPI

• Benefits– ensure safety and health of Canadians– improve the performance of Canada’s CPI– support decision making at all levels of government– reduce economic, environmental, and social impacts of CPI– evaluate impact of funding on performance of CPI

Approach

Questions?

Zoubir Lounis, Ph.D., P. [email protected]: (613) 993-5412

framework for assessment of state performance and management of canada’s core public...

Documents