Scholarly article on topic 'Life Cycle Cost Analysis – Integral Part of Road Network Management System'

Life Cycle Cost Analysis – Integral Part of Road Network Management System Academic research paper on "Civil engineering"

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Procedia Engineering
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{"Pavement Management System" / "Life-Cycle Cost Analysis" / "Road Network Administration" / "Cost Benefit Analysis" / "Maintenance Repair & Rehabilitation"}

Abstract of research paper on Civil engineering, author of scientific article — Jan Mikolaj, Lubos Remek

Abstract The article deals with economical aspect of Slovakia's Pavement Management System (PMS) – Road Network Management System (RNMS). Economic efficiency is a criterion, which enables us to create incisive outputs like strategy for allocation of limited funds between particular road sections, or the total funding amount necessary for preserving the road network in serviceable condition. In principle, economic efficiency assessment evaluates the impact of all Maintenance Repair & Rehabilitation (MR&R) actions. The positive effect – improvement of current state − of these actions has to overweight their construction costs. Economic efficiency can be evaluated by several methods, however, most commonly used is the Life-Cycle Cost Analysis (LCCA), which evaluates costs of various variants of MR&R actions.

Academic research paper on topic "Life Cycle Cost Analysis – Integral Part of Road Network Management System"

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ScienceDirect Procedía

Engineering

Procedía Engineering 91 (2014) 487 - 492 -

www.elsevier.com/locate/proeedia

XXIII R-S-P seminar, Theoretical Foundation of Civil Engineering (23RSP) (TFoCE 2014)

Life Cycle Cost Analysis - Integral Part of Road Network

Management System

Jan Mikolaja, Lubos Remeka *

aDepartment of Construction Management, Faculty of Civil Engineering, University of Zilina, Univerzitna 8215/1, 01026 Zilina

Abstract

The article deals with economical aspect of Slovakia's Pavement Management System (PMS) - Road Network Management System (RNMS). Economic efficiency is a criterion, which enables us to create incisive outputs like strategy for allocation of limited funds between particular road sections, or the total funding amount necessary for preserving the road network in serviceable condition. In principle, economic efficiency assessment evaluates the impact of all Maintenance Repair & Rehabilitation (MR&R) actions. The positive effect - improvement of current state - of these actions has to overweight their construction costs. Economic efficiency can be evaluated by several methods, however, most commonly used is the Life-Cycle Cost Analysis (LCCA), which evaluates costs of various variants of MR&R actions.

© 2014The Authors.Publishedby ElsevierLtd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/).

Peer-review underresponsibility of organizing committee of the XXIII R-S-P seminar, Theoretical Foundation of Civil Engineering (23RSP)

Keywords: Pavement Management System, Life-Cycle Cost Analysis, Road Network Administration, Cost Benefit Analysis, Maintenance Repair & Rehabilitation

CrossMar]

1. Introduction

Within the scope of LCCA, impact of chosen MR&R action on particular pavement is evaluated, as each method has different costs and different impact on the improvement of technical parameters, such as increased serviceability or prolonged service life.

* Corresponding author. Tel.: +421-41-513-5836; fax: +421-41-513-5510. E-mail address: lubos.remek@fstav.uniza.sk

1877-7058 © 2014 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/).

Peer-review under responsibility of organizing committee of the XXIII R-S-P seminar, Theoretical Foundation of Civil Engineering (23RSP) doi: 10.1016/j.proeng.2014.12.031

Nomenclature

AD Annual depreciation cost of vehicle, [€];

B Pavement structure parameter

CBA Cost-Benefit Analysis

CFF Hourly cost of freight forwarders, [€/hour]

CTT Circular Test Track

DW Crew wages, [€]

HDM Highway Design and Management

IRI International Roughness Index

IRR Internal Rate of Return

Katg Annual transportation growth coefficient

Kdeg Coefficient of function predicting condition of the pavement

LCCA Life-Cycle Cost Analysis

MR&R Maintenance Repair & Rehabilitation

n Loading repetitions

N Load repetition for pavement lifespan

NPV Net Present Value

OC Operational capacity

p(x) Pavement deterioration parameter

PCH Physical characteristics- horizontal and vertical alignment, category of the communication

PMS Pavement Management System

PP Payback Period

RNMS Road Network Management System

RT Road tax, [€]

RUB Road user benefits

RUC Road user costs, [€]

RUCdn Road user costs in "do nothing" variant

RUCds Road user costs in "do something" variant

SAL Standard axle load

T Years 1 - Y

TCH Traffic characteristic- intensity and composition of traffic

TTC Travel time costs, [€]

VEL Economic life of vehicle

VFCH Vehicle fleet characteristic- category of vehicles and their technical level

VI Vehicle insurance costs, [€]

VOC Vehicle operating costs, [€]

Y Service life of MR&R action

Furthermore, impact on road user costs and social & environmental costs is evaluated. The economic efficiency analysis is carried out with the use of Cost-Benefit Analysis. CBA evaluates positive impacts - benefits - related to improved operational parameters of the pavement in comparison to costs for applied MR&R actions. The Payback Period, Internal Rate of Return and Net Present Value are economic indicators of CBA.

This article gives an overview of most crucial part of LCCA - estimation of benefits, and describes the objective of CBA and its position within RNMS processes.

2. Illustrations

Identification and calculation of benefits generated through repaired pavements is a key factor for economic efficiency calculation. Benefits are calculated as a difference in transportation costs before the MR&R action and

decreased transportation costs stemming from improved pavement parameters as a result of the MR&R action. Benefits may be internal or external. Internal benefits are the road user costs, which consist of vehicle operating costs and travel time costs. External benefits are savings from emission, noise and accident rate reduction.

Fig. 1. Hyperbolization of road user costs dependency from pavement condition.

Dust particular matter and vibration are not crucial, but they monetization adds to the overall benefits. At this point they are not included in the RNMS. The vehicle operating costs are the transportation costs, which include fuel consumption, lubricant consumption, car maintenance, wearing of tires, and transportation time of cargo and passengers. Vehicle operating costs are a function of following factors:

uc = voc + ttc = f (tch, oc, pch, vfch) (1)

In the road user cost calculation, HDM coefficients are employed [1]. Those coefficients are based on horizontal and vertical alignment of the road. Among all surface characteristics of the pavement, the most important is the longitudinal roughness expressed through International Roughness Index. The calculation of user cost is defined for the consumption of fuel, lubricants, travel time, tire wear, spare parts and vehicle maintenance.

Time savings are the result of increased speed on repaired road section, and they can be monetized. The changes in travel time are adjusted by Highway Development and Management coefficients. For the monetization of time savings, it is important to know, whether we deal with the time of passengers or cargo transportation time. Currently, in the calculations, we are considering only cargo transportation times.

One-hour costs of freight forwarders are used to calculate total cost of total cargo transportation time. The hourly cost of freight forwarders is calculated according to equation (2).

ad + dw + rt + vi

— (2)

cff = -

Road user benefits are calculated as savings, i.e. difference between higher road user costs prior to the MR&R action and road user costs after the MR&R action. Each MR&R method has its expected serviceability, defined by its pavement performance functions - equation (3).

rub = j\{rucl

■ kleg ■ katg \t

kleg - 1

The coefficient of degradation Kdeg, equation (4), is a mathematical expression for degradation of surface characteristics. This coefficient is a parameter of a fundamental importance for the accuracy and validity of economic efficiency calculation.

For the needs of the RNMS, the trend lines for degradation of skid resistance, longitudinal and transverse roughness and surface distress were derived according to outputs of Circular Test Track, which is an outdoor accelerated pavement testing facility [2] [3]. At this facility, several pavement designs were tested and trend lines for degradation were derived for various traffic intensities. All tests performed on this facility were carried out in 1:1 scale - real life traffic load was applied on real life pavements - this way, accuracy of the results was ensured and these results could be used to derive exact equations. The equations arise as result of first performed measurements [4] and, at present, they are being refined on the base of cyclical measurement performed by the department of road databank. These equations, since they were deterministic in their nature, were derived on the basis of regression analysis. As an

example, we present the trend line for degradation of longitudinal roughness for specific pavement type in Figure 2. In this Figure, n is the number of SAL repetitions from the start of service to the expected date of pavement repair; N is the total number of SAL repetitions needed to achieve the load limit value. In this case, the parameter B 2.0 was derived for flexible pavements and parameter B 3.0 was derived for semi-rigid pavements. A warning value is at 60% difference between initial and limit value. Critical value is 40%.

* Stabilised Base ' Granular Base

Fig. 2. Degradation functions of IRI for flexible pavements. [5]

Currently, the CTT is not in service anymore, mainly due to energy costs of its operation. At present, the trend lines of degradation are being verified using results of measurements carried out for the needs of Slovak Road Database [6]. However, given the large number of input variables and conditions, and thus the large dispersion of the results, construction of a new experimental test facility started at University of Zilina. This facility will simulate traffic load, and subsequently, scrutinize inducted pavement response on a 1:1 model. This research will allow us to analyze all the physical-mechanical properties of the pavement under given conditions. Subsequently, it will be possible, at the level of absolute model, to analyze all the parameters by specifying their existing trend lines of degradation.

Pa ra meter x=n/N

Apart from trend lines for degradation of skid resistance, longitudinal and transverse roughness and surface distress, bearing capacity is also a significant factor influencing the overall results [7], however, the calculations performed in the Comprehensive Analysis of the Pavement Bearing Capacity software are out of scope of this article.

3. Cost benefit analysis

Cost-benefit analysis is a formal analysis of the impacts of a measure or programme, designed to assess whether the advantages (benefits) of the measure or programme are greater than its disadvantages (costs).

The calculation of economic efficiency of selected repairs is based on comparison of the benefits they will produce and their construction and maintenance costs. In view of the fact that it is necessary to incorporate a huge amount of data from the pavement evaluation, future maintenance costs, year in which the repair will take place, expected service life of the repair and calculated benefits, an algorithm of this procedure was created. Diagram of the algorithm is shown in Figure 4. The construction costs for particular MR&R method are included in the library of technologies, which is annually actualized with new market prices, paid by the administrator.

For project level, the CBA output shows if and how effective the repair action is. Economic indicators have threshold at which the project can be called „effective". IRR has to be higher than discount rate; net present value has to be higher than zero, Benefit-Cost Ratio has to be higher than 1.0 and payback period has to fall within the lifespan of repaired pavement.

Fig. 4. CBA algorithm within RNMS.

For road network level, the final output of the whole CBA is used in a cumulative table, which includes a final list of selected road sections and corresponding repair types. The table shows all necessary data required for final decision, In particular pavement operating condition index, appropriate repair action, traffic load, and, as a CBA output - repair

procurement costs and internal rate of return. Price for the repair is only an estimated value; the real value will be based on competition process where contractor for the construction works will be selected.

4. Conclusion

The application of LCCA and CBA provides us with fund allocation strategies and creation of site specific plans for MR&R actions, i.e. plans for meeting the performance objective. The application proved that the resources are allocated to road sections which have the highest demand for repairs, thus financial funds are used effectively. The saved funds are in turn used as additional resources for further repairs. Another important fact is that this systematic approach increased the discipline of subcontractors of repair works, employed by road administrators. The road network administrator has, by means of LCCA, a huge number of results, enabling him to optimize his activities; for example, the trend lines of roughness, skid resistance or surface damage.

RNMS provides a full set of outputs for network and project level assessment. In particular, the prioritization of fund expenditures allocated for MR&R policies and creation of site specific plans for MR&R actions, i.e. plans for meeting the performance objective. In addition, several others outputs are generated, for instance pavement distress data and traffic related data, data regarding the results of the evaluation - pavement operating condition index, IRI, selected MR&R technology, their costs, traffic load and internal rate of return.

Acknowledgements

The research is supported by the European Regional Development Fund and the Slovak state budget for the project "Research Centre of University of Zilina", ITMS 26220220183.

References

[1] T. Watanatada, et al., The Highway Design and Maintenance Model: Description of the HDM-III Model. Baltimore: Johns Hopkins University Press, 1987.

[2] Z. Benko, Pavement Management Systems Employed by Slovak Road Administration. Proceedings of Q-2012 conference: Construction, Financing and Management of Roads and Motorways, University of Zilina, ISBN 978-80-554-0572-8, 2012.

[3] J. Celko, M. Kovác, M. Decky, Analysis of Selected Pavement Serviceability parameters. Communications: Scientific Letters of the University of Zilina. 3/2011, ISSN 1335-4205, 2011.

[4] European Commission, COST 324 - Long Term Performance of Road Pavements. Luxembourg: Office for Official Publications of the European Communities, 1997.

[5] F. Schlosser, et al., Rheological characteristics of asphalt mixtures extracted from Circular Test Track: Testing of Bituminous Mixtures, VU report no. 93/SvF/98. University of Zilina, 1998.

[6] Research Institute of Engineering Constructions, Report no. 05-514-904 04 phase 3 Assessment of pavement performance and its development. Bratislava: Research Institute of Engineering Constructions, 1993.

[7] J. Komacka, Change of Bearing Capacity Characteristics of Asphalt Pavement, Communications: Scientific Letters of the University of Zilina, 3/2011, ISSN 1335-4205, 2011