Life-Cycle Cost Management of Interlocking Concrete Pavements

February 5, 2008

LIFE-CYCLE MANAGEMENT OF INTERLOCKING CONCRETE PAVEMENT

By:

Applied Research Associates, Inc. 5401 Eglinton Avenue West, Suite 204

Toronto, Ontario M9C 5K6 Telephone: (416) 621-9555 Facsimile: (416) 621-4917

Web: www.ara.com/transportation

TABLE OF CONTENTS

1.0 Introduction ........................................................................................................................ 2 1.1 Life-Cycle Costing......................................................................................................... 2 1.2 Scope.............................................................................................................................. 2

2.0 Initial Design Life of Interlocking Concrete Pavements .................................................... 3 2.1 Data Source .................................................................................................................... 3 2.2 Level of Service ............................................................................................................. 4

3.0 Maintenance and Rehabilitation Needs for Interlocking Concrete Block Pavements........ 5 3.1 Initial Interlocking Concrete Block Pavement Design................................................... 5 3.2 Estimating Activity Costs .............................................................................................. 6 3.3 Maintenance and Rehabilitation Plan............................................................................. 6

4.0 Comparable FLEXIBLE and Rigid Structure and M&R Program..................................... 7 4.1 Flexible Pavement Structure .......................................................................................... 8 4.2 Rigid Pavement Structure .............................................................................................. 9

5.0 Estimating Total Life-Cycle Cost....................................................................................... 9 5.1 Calculation of Net Present Value................................................................................. 10 5.2 Pavement Residual Value ............................................................................................ 10 5.3 Life-Cycle Cost (LCC)................................................................................................. 10

6.0 Conclusions ...................................................................................................................... 12

7.0 References ........................................................................................................................ 12

LIST OF APPENDICES

APPENDIX A – Example Life-Cycle Cost Analyses

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1.0 INTRODUCTION

Life-cycle costing has become an essential component of any modern infrastructure design. It has long been realized that maintenance and rehabilitation costs, not just the immediate initial construction costs should be considered when evaluating similar pavement alternatives. Applied Research Associates, Inc. (ARA) was retained by the Interlocking Concrete Pavement Institute (ICPI) to develop some guidelines and a spreadsheet model to develop realistic life-cycle cost procedures for flexible, rigid and interlocking concrete block pavements for low traffic volume pavements.

As a part of the development of pavement design and management tools for the ICPI, ARA has developed appropriate pavement design, maintenance and rehabilitation (M&R) procedures to document the life-cycle costs (LCC) of interlocking concrete block pavements. These tools and procedures can be used to document the life-cycle cost benefits of interlocking concrete block pavements compared to flexible and rigid pavements.

1.1 Life-Cycle Costing

The FHWA [1] describes LCCA as “an analysis technique that builds on the well-founded principles of economic analysis to evaluate the over-all-long-term economic efficiency between competing alternative investment options.” The comparison of life-cycle costs has become standard to not only compare different pavement types, but also evaluate different feasible rehabilitation plans over the service life of a pavement.

Municipal pavements are typically designed for an initial service life of between 10 and 20 years. At the end of the service life, some form of rehabilitation action such as a mill and overlay for flexible pavements, concrete pavement restoration treatment (e.g. slab repairs, crack sealing, etc.) for rigid pavements or removal and resetting of interlocking concrete blocks for interlocking concrete pavements (ICP) is completed.

The actual service life of both the initial pavement construction and rehabilitation treatment is dependant on a variety of factors including type and composition of the traffic, timeliness of maintenance treatments, and environmental factors such as temperature and precipitation. In order to develop comparative cost estimates to determine the whole life cost of the different pavement types, it is necessary to know the timing, type and quantities of repairs and their service life. The service life of a pavement is defined as the time between initial construction and the time when the pavement reaches a minimum acceptable level of service. Life-cycle costing is a technique that quantifies all of the costs necessary to construct and maintain a pavement over a set analysis period, typically between 25 and 50 years. Future costs are discounted to today’s dollars by using a discount rate which takes inflation and interest rates in account to determine the net present value of future costs. By comparing the total life-cycle cost of two or more pavement options, it is possible to make informed decisions as to the best pavement alternative for a particular application.

1.2 Scope

The development of a life-cycle cost tool is important to allow flexibility when analyzing a variety of pavement type options. To evaluate the life-cycle cost it is important to evaluate the costs in terms of several key parameters:

• Life-cycle costing parameters o Analysis period o Discount rate

• Initial pavement costs

3

o Design o Construction

• Maintenance and rehabilitation activities o Types o Timing o Cost

All of these factors should be considered for interlocking concrete, flexible, and rigid pavements. A Microsoft© Excel based tool has been developed to assist agencies and practitioners in evaluating the total costs of the various pavement alternatives.

2.0 INITIAL DESIGN LIFE OF INTERLOCKING CONCRETE PAVEMENTS

The initial design and construction of pavements is a critical factor in the life-cycle cost evaluation procedure. A pavement built for its appropriate traffic and environmental conditions will have a reasonable service life and provide a functional and safe platform for the travelling public. The service life of a pavement is usually established during the initial design considering the subgrade, pavement layer materials and their thicknesses and the anticipated traffic that will utilize the roadway. This service life can be somewhat variable depending on the environmental and loading conditions to which the pavement is exposed during its service life. By monitoring and rating the pavement performance over its service life using standard pavement management tools such as the pavement condition index (PCI), it is possible to establish typical pavement performance curves for the pavement [2].

To determine the expected life of a pavement, the measured condition, along with a minimum acceptable level of service is used. The typical path of deterioration is monitored over the life of the pavement until the pavement reaches the typical terminal level of serviceability, at which point very few field data points are available.

To generate the deterioration path, several possible techniques can be used. A common statistical technique called regression consists of selecting an appropriate form for modelling pavement condition deterioration and using the method of least squares to determine the best fit model. This method calculates the best-fitting line for the observed data by minimizing the sum of the squares of the vertical deviations from each data point to the line (if a point lies on the fitted line exactly, then its vertical deviation is 0).

2.1 Data Source

The pavement performance data was collected from 48 interlocking concrete block pavement roadways located in 7 cities across North America. The detailed pavement condition assessments were completed based on the draft procedure in the Standard Practice for Pavement Condition Index Surveys for Concrete Block Pavement [2]. The survey procedure is modelled on the U.S. Army Corps of Engineers MicroPAVER distress guide as published by ASTM [3].

The surveys were completed in the summer and fall of 2007 on interlocking concrete block pavements in the following cities:

• Baltimore, MD • Boston, MA • Hamilton, ON • North Bay, ON • San Antonio, TX

4

• Syracuse, NY • Vancouver, BC

To compare the various pavements and their stage of deterioration, construction history was determined through local knowledge of the various projects. The construction history included the initial construction date as well as any information regarding maintenance and rehabilitation treatments. The pavement age was then used in conjunction with the current pavement condition to develop a deterministic regression model.

The results of the performance modelling is shown in Figure 1. From this data it can be seen that a large degree of variability is measured in the field. This type of variability is common among all pavement types and reflects many factors, other than age, that affect the service life of the pavement. A general trend can be seen from the regression indicating the typical path of deterioration.

0102030405060708090

100

0 5 10 15 20 25

Age (Years)

Pave

men

t Con

ditio

n In

dex

Figure 1. Pavement Condition Index and General Performance Model for Interlocking Concrete Block Pavements

The path of deterioration shown in Figure 1, shows that a typical interlocking concrete brick pavement will show a relatively slow deterioration in the first 8 years of service.

2.2 Level of Service

The minimum acceptable level of service is an important decision that must be made by a designer. The maximum state of deterioration that a pavement is expected to reach can greatly change the service life. It many cases however, the service level of a pavement must be maintained at a high level due to the types of use it will be exposed to.

The level of service can be described in terms of a variety of types of condition indicators such as structural capacity, ride quality, or visual distress. On most low volume roads, the visual condition is typically used because it can represent the other factors in terms of an overall rating. With the relatively

5

low operating speed of most low volume pavements the impact of other functional performance factors is reduced. A typical rating scale for the visual condition in terms of the PCI is show in Figure 2.

Based on the condition descriptions in Figure 2 and the level of service measured during the field inspections, a typical rating of a PCI of 60 is recommended as a minimum level of service. Once a pavement passes this level, substantial repairs throughout a section are likely required to bring the pavement up to an excellent condition level. Using a typical minimum serviceability trigger value PCI of 60, this data would indicate a typical ICP service life of 20 years. It was noted that the variability increases significantly after 8 years into the service life. The data also shows a group of pavement sections with relatively low PCI values (between 40 and 60) which do not seem to be grouped with the remainder of the pavement sections. If these sections were removed from the population, the performance curve would cross the PCI of 60 trigger value closer to 30 years.

Excellent100

85705540

PCI Rating

Failed

Very Good

Good

Fair

Poor

Very Poor25

010

Excellent100

85705540

PCI Rating

Failed

Very Good

Good

Fair

Poor

Very Poor25

010

Figure 2. Level of Service Based on Pavement Condition Index

It is possible however to consider reduced level of service requirements for very low volume roads or parking areas. Due to the low speed of vehicles and the limited use, consideration could be given to setting the minimum acceptable PCI at 50 for these types of pavements.

3.0 MAINTENANCE AND REHABILITATION NEEDS FOR INTERLOCKING CONCRETE BLOCK PAVEMENTS

There is little doubt as to the importance of the initial construction cost of a pavement. However the on-going maintenance and rehabilitation costs can be a significant cost over the entire life-cycle of a pavement. To account for these costs, pavement maintenance of rehabilitation activities are typically scheduled to occur at various times to maintain and improve the serviceability of the pavement. The timing of the activities, in conjunction with the cost to perform the activities is then combined to estimate the total life-cycle cost.

3.1 Initial Interlocking Concrete Block Pavement Design

The cost to design and construct the initial pavement structure is typically the largest expense over the life-cycle. The initial pavement design of an interlocking concrete block pavement is very dependent on many factors such as traffic level, environment, and materials used. For the purpose of the life-cycle costing, a typical structure, based on an example from the ASCE Draft Pre-Standard for the Structural Design of Interlocking Concrete Pavement [4], has been used as an example:

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Design Details

Design Traffic 300,000 ESALs Drainage Type Fair Subgrade Type CL (Mr = 20 MPa)

Concrete pavers (with sand filled joints) – 80 mm thickness Bedding sand – 25 mm thickness Granular base – 150 mm thickness Granular subbase – 295 mm thickness

This is adequate for the types of traffic typically supported by a municipal roadway.

3.2 Estimating Activity Costs

One of the key components for the evaluation of total costs over the pavement life-cycle is the estimation of maintenance and rehabilitation costs. This is typically accomplished by reviewing the potential activities that will occur through out the service life of a pavement, their frequency and costs.

The maintenance and rehabilitation costs used in the analysis are based on current dollars. Adjustments due to inflation and discounting are taken into account later during the life-cycle cost analysis. The unit costs represent the whole cost to complete the maintenance and rehabilitation activity, including labor, equipment and materials. An example of the estimated unit costs for the expected activities on the interlocking concrete block pavements are given in Table 1. It must be recognized that unit cost can vary significantly depending on location, size of the project, availability of materials and contractors, etc.

Table 1. Unit Costs for Mainenance and Rehabilitation

Activity Unit Cost ($) Unit Bedding Sand and Paver Installation $40.00 m2 Granular Base $13.00 tonne Granular Subbase $8.50 tonne Replace Cracked Pavers $40.00 m2 Replace Worn/Rutted Pavers (wheelpath) $60.00 m2

3.3 Maintenance and Rehabilitation Plan

The maintenance and rehabilitation (M&R) plan for the block pavements is set out as a typical scenario to maintain the pavement in a cost effective and serviceable manner and reflects maintenance and rehabilitation activities and timing. These activities are typically include mill and overlay for flexible pavement, concrete pavement restoration (e.g. slab repairs, crack sealing, etc.) for rigid pavement and replacement and resetting of interlocking concrete blocks for an ICP. The typical life-cycle and timing of maintenance and rehabilitation treatments is illustrated in Figure 3.

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Time (Years)

Preventive Maint.

Routine Maint.

Rehabilitation

Reconstruction

Good

Poor

Time (Years)

Preventive Maint.

Routine Maint.

Rehabilitation

Reconstruction

Good

Poor

Figure 3. Timing of Maintenance and Rehabilitation Activities

A typical plan for maintenance and rehabilitation expected for an interlocking concrete pavement is outlined in Table 2. This plan should be evaluated on a project by project basis before implementation in the field to ensure the correct timing of activities.

Table 2. Unit Costs for Maintenance and Rehabilitation

Year Activity Quantity (%)

8 Replace Cracked Pavers 2 20 Replace Worn/Rutted Pavers (wheelpath) 5 28 Replace Cracked Pavers 2 35 Replace Worn/Rutted Pavers (wheelpath) 5

4.0 COMPARABLE FLEXIBLE AND RIGID STRUCTURE AND M&R PROGRAM

The key benefit of a life-cycle cost analysis is the ability to compare multiple pavement structures that have different initial cross-section and hence different maintenance strategies. Flexible and rigid pavement designs have been developed based on the matching geometric and traffic conditions to the interlocking concrete block pavement example. Unit costs for the flexible and rigid pavement structures can be found in Table 3 [5].

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Table 3. Unit Costs for Mainenance and Rehabilitation

Activity Unit Cost ($) Unit Doweled Jointed Concrete Pavement (200 mm) 60.00 m2 Plain Jointed Concrete Pavement (200 mm) 45.00 m2 Asphalt Concrete (Surface) 95.00 tonne Asphalt Concrete (Base) 85.00 tonne Granular Base 13.00 tonne Granular Subbase 8.50 tonne Rout and Seal Crack 2.00 m Reseal Joints 2.00 m Asphalt Patching 7.00 m2 Mill and Overlay Pavement 86.00 tonne Concrete Pavement Restoration 160.00 m2

4.1 Flexible Pavement Structure

Flexible pavement structures are typically composed of an asphalt concrete surface over granular base and subbase combination. A typical flexible pavement structure, based on the 1993 AASHTO Design Guide, with a comparable traffic and subgrade condition to the interlocking concrete block pavement example is:

Design Details

Design Traffic 300,000 ESALs Drainage Type Fair Subgrade Type CL (Mr = 20 MPa) SNDesign 97.4 mm

Asphalt Concrete – 100 mm thickness

Granular base – 150 mm thickness

Granular subbase – 400 mm thickness

This structure is a pretty typical for a municipal pavement. A typical maintenance and rehabilitation plan for this flexible pavement structure is given in Table 4.

Table 4. Flexible Pavement Mainenance and Rehabilitation Plan


4 Rout and Seal Cracks 5 8 Machine Patching 5

15 Mill and Overlay (50 mm) 100 19 Rout and Seal Cracks 10 22 Machine Patching 10 25 Mill and Overlay (90 mm) 100 27 Rout and Seal Cracks 10 30 Machine Patching 10 37 Mill and Overlay (50 mm) 100

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4.2 Rigid Pavement Structure

Rigid pavement structures are typically composed of a Portland Cement Concrete (PCC) layer over a granular base material. A typical PCC design assuming jointed plain concrete pavement is provided below:

Design Details

Design Traffic 300,000 ESALs Drainage Type Fair Subgrade Type CL (K = 51.5 MPa/m) DDesign 200 mm (minimum recommended PCC thickness)

PCC Pavement – 200 mm thickness

Granular subbase – 150 mm thickness

Table 5. Rigid Pavement Mainenance and Rehabilitation Plan


5 Reseal Joints 5 15 Minor Concrete Pavement Repair 2 18 Reseal Joints 15 25 Major Concrete Pavement Repair 5 30 Reseal Joints 5 40 Minor Concrete Pavement Repair 2 43 Reseal Joints 15

5.0 ESTIMATING TOTAL LIFE-CYCLE COST

The estimation of the total life-cycle cost is an aggregate of the initial and the maintenance and rehabilitation costs for each alternative. The inputs used for evaluating the total life-cycle cost are slightly more complicated. This process is handled by a spreadsheet tool to provide accurate and consistent numbers.

The total life-cycle combines many factors for all three pavement type scenarios to determine the lowest life-cycle cost. The required inputs include:

• General inputs o Analysis period o Discount rate o Site description/dimensions

• Interlocking concrete block pavements o Unit costs o Initial pavement layer thickness o Maintenance and rehabilitation plan and quantities

• Flexible pavements o Unit costs

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o Initial pavement layer thickness o Maintenance and rehabilitation plan and quantities

• Rigid pavements o Unit costs o Initial pavement layer thickness o Maintenance and rehabilitation plan and quantities

5.1 Calculation of Net Present Value

The costs distributed over the pavement are typically translated into a Net Present Value (NPV). The NPV represents the total cost today that would be required, accounting for the interest and inflation in terms of the discount rate. The NPV of all activities are summed up to estimate the total maintenance and rehabilitation cost.

( )

( )∑ +=

iAge

i

RateDiscountCostRM

1&Cost R&M Total

The discount rate used in the analysis represents the potential interest rate that can be achieved. The discount rate typically reflects the social discount rate for public sector projects and is dependent on many factors such as current economic environment, market risk, and many other potential factors.

5.2 Pavement Residual Value

To ensure fair comparison of the alternatives, residual value of any unused pavement rehabilitation activity at the end of the analysis period must be included in the life-cycle cost analysis. The residual value is estimated by the straight line depreciation of the last capital activity cost. The Prorated Life method is used in the LCCA procedure to estimate the residual value. The recoverable cost is estimated by dividing the remaining life of the last rehabilitation treatment, by the expected life of the treatment.

⎟⎟⎠

⎞⎜⎜⎝

⎛ −⋅=

LifeServiceAgeActivityLifeServiceCostRM &Value Residual

To determine the salvage value, the last major rehabilitation activity is used. Based on the year of implementation of the last rehabilitation, the expected service life (from the Unit Costs table) and the activity cost, a proportion of the initial cost is determined. The residual value, at the end of the design period, is then converted in to a net present value. The residual value is then subtracted from the other costs.

5.3 Life-Cycle Cost (LCC)

The total cost to construct and maintain each design option is the key focus of a LCCA. To accomplish this, the total sum of all costs, in equivalent NPV is required. The total cost is thus calculated as:

LCC = Initial Cost + Total M&R Cost – Residual Value

This value can then be used to benchmark other potential options and determine which is the most cost effective.

A worked example of total life-cycle costs using the above data and procedures is provided in Appendix A. A summary of the overall results is provided in Table 6.

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Table 6. Summary of Present Worth of Example Life-Cycle Cost Analysis (Design Traffic = 300,000 ESALs)

Pavement Type Initial Cost ($) Maintenance and

Rehabilitation Costs ($) Total Present Worth

of Costs ($) Asphalt Concrete 252,694 112,465 365,158 Concrete 482,175 44,094 526,269 ICP 373,549 20,012 393,561

The initial and life-cycle costs were recalculated for equivalent pavement structures with a design traffic of 5 million ESALs. The results of the analysis are provided in Table 7 and on Figure 4. This analysis also includes an ICP design incorporating an asphalt treated base over a granular subbase.

Table 7. Summary of Present Worth of Example Life-Cycle Cost Analysis (Design Traffic = 5,000,000 ESALs)

Pavement Type Initial Cost ($) Maintenance and

Rehabilitation Costs ($) Total Present Worth

of Costs ($) Asphalt Concrete 368,400 112,465 480,865 Concrete 519,675 44,094 563,769 ICP Granular Base 451,388 20,012 471,400 ICP Asphalt Base 465,025 15,470 480,495

Life-Cycle Cost Comparison

420,000

440,000

460,000

480,000

500,000

520,000

540,000

560,000

580,000

Asphalt Concrete Concrete ICP Granular Base ICP Asphalt Base

Pavement Type

Life

-Cyc

le C

ost/2

lane

-km

Figure 4. Total Life-Cycle Cost Comparison for 5 Million ESAL Pavement Designs

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6.0 CONCLUSIONS

The development of a Life-Cycle Cost tool allows for the examination of various design options to determine which pavement type is the most cost effective over the total life-cycle of the pavement. The LCCA tool developed for the ICPI can be customized on a site by site basis to allow for specific pavement details and costs to be used.

7.0 REFERENCES

1. Walls, James III and Michael R. Smith. Life-Cycle cost Analysis in Pavement Design – Interim Technical Bulletin. FHWA Report FHWA-SA-98-079, September 1998.

2. Interlocking Concrete Pavement Institute, Standard Practice for Pavement Condition Index Surveys for Concrete Block Pavement, Washington, D.C., December 2007.

3. American Society for Testing Materials, ASTM D6433-07 Standard Practice for Roads and Parking Lots Pavement Condition Index Surveys, ASTM, Washington, D.C., 2003.

4. Smith, David R.. Draft Pre-Standard, Structural Design of Interlocking Concrete Pavement. American Society of Civil Engineers, Draft 07/16/07.

5. Applied Research Associates, Inc., Estimation of the Representative Annualized Capital and Maintenance Costs of Roads by Functional Class, March 31, 2006, http://www.tc.gc.ca/pol/en/aca/fci/menu.htm.

A.1

APPENDIX A

EXAMPLE LIFE-CYCLE COST ANALYSES

SI Urban PaveUS Customary Parking Lot

Project Description Denver Examples

Location Denver, Colorado

Type of Project Urban Pavement Design

Analysis Period 40

Discount Rate 4.0

Construction Year 2008

Measurement Units SI

LIFE-CYCLE COST ANALYSIS

LIFE CYCLE COST ANALYSIS SPREADSHEET

BASIC INPUT PARAMETERS

INTERLOCKING CONCRETE PAVEMENT INSTITUTE

Life-Cycle Cost Comparison

420,000

440,000

460,000

480,000

500,000

520,000

540,000

560,000

580,000

Asphalt Concrete Concrete ICP Granular Base ICP Asphalt Base

Pavement Type

Life

-Cyc

le C

ost/2

lane

-km

No. Description Mean Price St. Deviation Unit1 Bedding Sand and Paver Installation $40.00 $4.00 Sq. m2 Granular Base $13.00 $2.00 Tonne3 Granular Subbase $8.50 $1.00 Tonne4 Replace Cracked Pavers $40.00 $4.00 Sq. m5 Replace Worn/Rutted Pavers (Wheelpath) $60.00 $6.00 Sq. m6 Doweled Jointed Concrete Pavement $60.00 $8.00 Sq. m7 Plain Jointed Concrete Pavement $45.00 $4.50 Sq. m8 Asphalt Concrete Surface $95.00 $8.00 Tonne9 Asphalt Concrete Base $85.00 $7.00 Tonne

10 Rout and Seal Cracks $2.00 $0.50 m11 Reseal Joints $2.00 $0.50 m12 Patching (%) $7.00 $1.00 Sq. m13 Mill and Overlay Asphalt Pavement $86.00 $8.60 Tonne14 Concrete Pavement Restoration $160.00 $16.00 Sq. m15

Denver ExamplesLIST OF CONSTRUCTION ITEMS

Project Definitions:Length of Section: 1000 m Analysis Period: 40.0Lane Width: 3.75 m Discount Rate: 4.0Number of Lanes: 2 m Initial Year of Construction: 2008

Total Pavement Area: 7,500 Sq. m

YEAR AMOUNT QTY. UNIT UNIT PRICE ST DEV COST PRESENT

WORTH

INITIAL CONSTRUCTION

0 7500 7500 Sq. m $40.00 $4.00 $300,000 $300,0000 150 2475 Tonne $13.00 $2.00 $32,175 $32,1750 295 4867.5 Tonne $8.50 $1.00 $41,374 $41,374

MAINTENANCE AND REHABILITATION ACTIVITIES


WORTH

8 150 150 Sq. m $40.00 $4.00 $6,000 $4,38420 375 375 Sq. m $60.00 $6.00 $22,500 $10,26928 150 150 Sq. m $40.00 $4.00 $6,000 $2,00135 375 375 Sq. m $60.00 $6.00 $22,500 $5,702

Granular Subbase

Example Project, Gainesville, Florida

LIFE CYCLE COST ANALYSISINTERLOCKING CONCRETE PAVEMENT

CONSTRUCTION ITEM

Bedding Sand and Paver InstallationGranular Base

MAINTENACE ACTIVITY

Replace Cracked PaversReplace Worn/Rutted Pavers (Wheelpath)Replace Cracked PaversReplace Worn/Rutted Pavers (Wheelpath)




WORTH


LIFE CYCLE COST ANALYSISINTERLOCKING CONCRETE PAVEMENT

CONSTRUCTION ITEM

TOTAL COST OF NEW CONSTRUCTION $373,549

TOTAL COST OF MAINTENANCE AND REHABILITATION $22,356

RESIDUAL VALUE -$2,343

PRESENT WORTH $393,561

EQUIVALENT UNIFORM ANNUAL COST $19,884

Top 10 Construction Item Costs

$6,000

$6,000

$22,500

$22,500

$32,175

$41,374

$300,000

$0 $50,000 $100,000 $150,000 $200,000 $250,000 $300,000 $350,000

Year 28, Replace Cracked Pavers

Year 8, Replace Cracked Pavers

Year 35, Replace Worn/Rutted Pavers(Wheelpath)

Year 20, Replace Worn/Rutted Pavers(Wheelpath)

Year 0, Granular Base

Year 0, Granular Subbase

Year 0, Bedding Sand and PaverInstallation

Actual Cost ($)




WORTH


0 50 918.75 Tonne $95.00 $8.00 $87,281 $87,2810 50 825 Tonne $85.00 $7.00 $70,125 $70,1250 150 2475 Tonne $13.00 $2.00 $32,175 $32,1750 450 7425 Tonne $8.50 $1.00 $63,113 $63,113



WORTH

4 500 500 m $2.00 $0.50 $1,000 $8558 5 375 Sq. m $7.00 $1.00 $2,625 $1,91815 50 918.75 Tonne $86.00 $8.60 $79,013 $43,87319 1000 1,000 m $2.00 $0.50 $2,000 $94922 10 750 Sq. m $7.00 $1.00 $5,250 $2,21525 90 1653.75 Tonne $86.00 $8.60 $142,223 $53,35027 1000 1000 m $2.00 $0.50 $2,000 $69430 10 750 Sq. m $7.00 $1.00 $5,250 $1,61937 50 918.75 Tonne $86.00 $8.60 $79,013 $18,512

Asphalt Concrete SurfaceAsphalt Concrete Base

Mill and Overlay Asphalt Pavement

Mill and Overlay Asphalt Pavement

Patching (%)Mill and Overlay Asphalt Pavement

CONSTRUCTION ITEM

LIFE CYCLE COST ANALYSISASPHALT CONCRETE PAVEMENT DESIGN (FLEXIBLE PAVEMENT)

Denver Examples, Denver, Colorado

MAINTENACE ACTIVITY

Rout and Seal Cracks

Rout and Seal CracksPatching (%)

Rout and Seal Cracks

Granular BaseGranular Subbase

Patching (%)




WORTHCONSTRUCTION ITEM

LIFE CYCLE COST ANALYSISASPHALT CONCRETE PAVEMENT DESIGN (FLEXIBLE PAVEMENT)








$2,625

$5,250

$5,250

$32,175

$63,113

$70,125

$79,013

$79,013

$87,281

$142,223

$0 $20,000 $40,000 $60,000 $80,000 $100,000 $120,000 $140,000 $160,000

Year 8, Patching (%)




Year 0, Granular Subbase

Year 0, Asphalt Concrete Base

Year 37, Mill and Overlay Asphalt Pavement


Year 0, Asphalt Concrete Surface


Actual Cost ($)


Total Pavement Area: 7,500 Sq. m 2500 Long. Concrete Joints (M or Ft) 1667 Trans. Concrete Joints (M or Ft)


WORTH


0 7500 7500 Sq. m $60.00 $8.00 $450,000 $450,0000 150 2475 Tonne $13.00 $2.00 $32,175 $32,175



WORTH

5 1625 1625 m $2.00 $0.50 $3,250 $2,67115 150 150 Sq. m $160.00 $16.00 $24,000 $13,32618 4875 4875 m $2.00 $0.50 $9,750 $4,81325 375 375 Sq. m $160.00 $16.00 $60,000 $22,50730 1625 1625 m $2.00 $0.50 $3,250 $1,00240 150 150 Sq. m $160.00 $16.00 $24,000 $4,99943 4875 4875 m $2.00 $0.50 $9,750 $1,805


LIFE CYCLE COST ANALYSISPORTLAND CEMENT CONCRETE PAVEMENT DESIGN (RIGID PAVEMENT)

CONSTRUCTION ITEM

Doweled Jointed Concrete PavementGranular Base

MAINTENACE ACTIVITY

Reseal JointsConcrete Pavement RestorationReseal JointsConcrete Pavement RestorationReseal JointsConcrete Pavement RestorationReseal Joints


Total Pavement Area: 7,500 Sq. m 2500 Long. Concrete Joints (M or Ft) 1667 Trans. Concrete Joints (M or Ft)


WORTH


LIFE CYCLE COST ANALYSISPORTLAND CEMENT CONCRETE PAVEMENT DESIGN (RIGID PAVEMENT)

CONSTRUCTION ITEM







$3,250

$3,250

$9,750

$9,750

$24,000

$24,000

$32,175

$60,000

$450,000

$0 $50,000 $100,000 $150,000 $200,000 $250,000 $300,000 $350,000 $400,000 $450,000 $500,000

Year 30, Reseal Joints




Year 40, Concrete Pavement Restoration




Year 0, Doweled Jointed Concrete Pavement

Actual Cost ($)

Analysis Period: 40 YearsDiscount Rate: 4 %

INTERLOCKING CONCRETE PAVEMENT

TOTAL COST OF NEW CONSTRUCTION: $373,549

TOTAL COST OF MAINTENANCE ACTIVITIES AND REHABILITATION: $22,356

RESIDUAL VALUE: -$2,343

PRESENT WORTH: $393,561

EQUIVALENT UNIFORM ANNUAL COST: $19,884

FLEXIBLE PAVEMENT






RIGID PAVEMENT






Urban Pavement Design

INTERLOCKING CONCRETE PAVEMENT INSTITUTELIFE CYCLE COST ANALYSIS

ECONOMIC ANALYSIS REPORT


Analysis Period: 40 YearsDiscount Rate: 4 %Note: This Analysis Assumes a St. Dev. of +/- 2 for Calculation of Lower & Higher Side Present Worth Values

Year Construction Item Cost Lower Side PW Higher Side

FLEXIBLE PAVEMENT ANALYSIS

INITIAL CONSTRUCTION IN YEAR 0

0 Asphalt Concrete Surface $87,281 $72,581 $87,281 $101,9810 Asphalt Concrete Base $70,125 $58,575 $70,125 $81,6750 Granular Base $32,175 $22,275 $32,175 $42,0750 Granular Subbase $63,113 $48,263 $63,113 $77,963

MAINTENANCE AND REHABILITATION ACTIVITIES4 Rout and Seal Cracks $1,000 $427 $855 $1,2828 Patching (%) $2,625 $1,370 $1,918 $2,466

15 Mill and Overlay Asphalt Pavement $79,013 $35,098 $43,873 $52,64719 Rout and Seal Cracks $2,000 $475 $949 $1,42422 Patching (%) $5,250 $1,582 $2,215 $2,84825 Mill and Overlay Asphalt Pavement $142,223 $42,680 $53,350 $64,02027 Rout and Seal Cracks $2,000 $347 $694 $1,04030 Patching (%) $5,250 $1,156 $1,619 $2,08137 Mill and Overlay Asphalt Pavement $79,013 $14,810 $18,512 $22,215

SUMMARY OF LIFE CYCLE DATA FOR FLEXIBLE PAVEMENT DESIGN

TOTAL COST OF NEW CONSTRUCTION $201,694 $252,694 $303,694

TOTAL COST OF MAINTENANCE AND REHABILITATION $97,946 $123,985 $150,024

RESIDUAL VALUE -$11,520 -$11,520 -$11,520

PRESENT WORTH $288,119 $365,158 $442,198

RIGID PAVEMENT ANALYSIS


0 Doweled Jointed Concrete Pavement $450,000 $330,000 $450,000 $570,0000 Granular Base $32,175 $22,275 $32,175 $42,075


DETAILED ECONOMIC ANALYSIS REPORT







MAINTENANCE AND REHABILITATION ACTIVITIES5 Reseal Joints $3,250 $1,336 $2,671 $4,007

15 Concrete Pavement Restoration $24,000 $10,661 $13,326 $15,99218 Reseal Joints $9,750 $2,406 $4,813 $7,21925 Concrete Pavement Restoration $60,000 $18,006 $22,507 $27,00830 Reseal Joints $3,250 $501 $1,002 $1,50340 Concrete Pavement Restoration $24,000 $3,999 $4,999 $5,99943 Reseal Joints $9,750 $903 $1,805 $2,708




RESIDUAL VALUE -$7,030 -$7,030 -$7,030

PRESENT WORTH $383,057 $526,269 $669,481

INTERLOCKING CONCRETE PAVEMENT (ICP) ANALYSIS


0 Bedding Sand and Paver Installation $300,000 $240,000 $300,000 $360,0000 Granular Base $32,175 $22,275 $32,175 $42,0750 Granular Subbase $41,374 $31,639 $41,374 $51,109






MAINTENANCE AND REHABILITATION ACTIVITIES8 Replace Cracked Pavers $6,000 $3,507 $4,384 $5,261

20 Replace Worn/Rutted Pavers (Wheelpath) $22,500 $8,215 $10,269 $12,32228 Replace Cracked Pavers $6,000 $1,601 $2,001 $2,40135 Replace Worn/Rutted Pavers (Wheelpath) $22,500 $4,561 $5,702 $6,842




RESIDUAL VALUE -$1,875 -$2,343 -$2,812

PRESENT WORTH $309,924 $393,561 $477,199

Documents

Life-Cycle Cost Management of Interlocking Concrete Pavements