Pavement Maintenance Management System for Urban Roads Using HDM-4

Transcription

1 INDIAN GEOTECHNICAL SOCIETY CHENNAI CHAPTER Pavement Maintenance Management System for Urban Roads Using HDM-4 ABSTRACT: Various maintenance treatments are being practiced in India for the urban roads. The type of treatment is at present selected arbitrarily by the field engineers without any scientific basis. In this study, optimum maintenance treatment is identified for the urban roads among the various alternatives recommended in Government of India specifications using a sophisticated and modern scientific tool namely HDM - 4 developed by the World bank. KEYWORDS: HDM-4, Urban roads, Pavement maintenance R. Sudhakar 1 Introduction The current maintenance practice in India is to provide the maintenance and rehabilitation strategies based on subjective judgment and engineering experience. The principal causes for the deterioration of roads and ineffectiveness of different maintenance strategies often remain unevaluated due to nonavailability of objective data base required for the analysis of various activities, such as, design, construction, maintenance, etc. Consequently, the gap between the allocation and requirements has been accumulating over the years. Road engineers, planners and managers are forced to make a more careful examination of cost effectiveness of various investment options due to the lack of financial resources. The development of scientific maintenance system will enable the engineers to project the requirement of funds to maintain the road network at a desired level of serviceability. HDM - 4 software tool developed by World Bank for global applications can be effectively utilized for identifying optimum maintenance strategy for highway pavements. In this paper, optimum pavement maintenance strategy is arrived using HDM - 4 analysis after making due calibration for the local conditions for the urban roads in India. Definitions of terms used in Pavement Maintenance The definitions for various terminologies used in pavement maintenance are given below (Haas, 1978); Deterioration Pavement deterioration is the process by which distress (defects) develop in the pavement under the combined effects of traffic loading and environmental conditions. Cracking Area Sum of rectangular areas circumscribing manifest distress (line cracks are assigned a width of 0.5m) expressed as a percentage of carriageway area. Ravelling Area Area of loss of material from wearing surface, expressed as a percentage of carriageway area. Number of Potholes Number of potholes per kilometer expressed in terms of the number of 'Standard' sized potholes of area 0.1m 2. A pothole is defined as an open cavity in road surface with at least 150mm diameter and at least 25mm depth. Edge Break Area Loss of Bituminous surface material (and possibly base materials) from the edge of the pavement, is expressed in m /Km. Roughness Deviations of surface from true planar surface with characteristic dimensions that affect vehicle dynamics, ride quality, dynamic of loads and drainage, expressed in the International Roughness Index, IRI (m/km) Structural Number The pavement strength is generally expressed in terms of Structural Number (SN). The structural number depends on subgrade strength and thickness and quality of various pavement layers. The sub grade strength is found by California Bearing Ratio (CBR) Test. This is a penetration test developed by the California Division of Highway, as a method for evaluating the stability of soil sub grade and other flexible pavement materials. The structural number is determined using the formula (Paterson, 1987), SN = a1 x t1 + a2 x t2 + a3 x t3+ where + a nx t n a 1, a2...a n are the strength coefficients of materials used indifferent pavement layers, t1, t2...t n are the corresponding thickness in inches. 1 P.G. Student, College of Engineering Guindy, Anna University

2 32 STUDENTS PAPER COMPETITION 2009 The strength of subgrade also affects the pavement strength. Hence, the Structural Number as determined above is modified to take in to account the subgrade effect, using the following formula (Paterson, 1987), MSN = SN (log CBR) (log CBR) where, MSN = Modified Structural Number SN = Structural Number CBR = Subgrade Strength at Field Conditions The strength co-efficient suggested for different pavement materials used in India are given in Table 1 (CRRI, 1994). Table 1 Strength co-efficient Layer / Specifications Strength Co-efficient Bituminous Concrete (BC) 40 mm 030 Bituminous Concrete (BC) 25 mm 0.28 Semi-Dense Bituminous Concrete (SDBC) 25 mm 0.25 Dense Bituminous Macadam (DBM) 0.28 Premix Carpet (PC) 20 mm (only in the case of overlaid pavements which 0.18 have PMC as original surfacing) Bituminous Macadam (BM) 0.18 Water Bound Macadam / (Lime Cement) stabilized 0.14 Granular Sub - Base (GSB) 0.11 Use of HDM - 4 in Pavement Maintenance The Highway design model was developed by the World Bank in It has been updated to Highway Development and Management Tool (HDM-4) in 1998, under the sponsorship of Permanent International Association of Road Congress (PIARC). It is ideally suited for making the total assessment of deterioration and economic returns so that optimum utilization of funds may also be achieved for roads. Also, it is recognized as a state-of-the-art system for the analysis of road maintenance and investment alternatives because of the following advantages (HDM - 4, 2001): > The incorporation of both agency costs and road user costs in a life-cycle cost analysis, > The use of calibration parameters for broad-based applicability in diverse climates and conditions, and > The use as an appropriate design tool for pavements, if properly calibrated, especially for developing countries, while borrowing design standards directly from the design specifications of industrialised countries. The data required for the HDM - 4 analysis are listed in the Table 2. HDM-4 supports flexible options for data analysis and results. Users can make printed or electronic reports. They can also export data and results to standard database for other users. HDM-4 can produce the following three types of output, which can assist road managers to make informed decisions: > Strategic road maintenance and development plans, produced from long-term predictions of road network performance, > Economic efficiency indicators, produced from analysis of individual road projects, > Multi-year work programs, produced from prioritization of several road projects. Table 2 HDM -4 Input data Input Road network data Vehicle fleet data Work standards Description Basic road details, geometries, pavement history, pavement condition etc. Basic characteristics of vehicle fleet, economical and financial costs, etc. Specifications for maintenance and improvement works Source: HDM - 4 manual - Vol. I (2001)

3 PAVEMENT MAINTENANCE MANAGEMENT SYSTEM USING HDM-4 33 Methodology adopted in this Study The methodology in this study involves five stages. In the first stage, the experimental stretches were identified and the preliminary data were collected. In the second stage, classified traffic surveys were conducted. The traffic data were converted in to Annual Average Daily Traffic (AADT) for the analysis. In the third stage, pavement evaluation was carried out by measuring the surface distresses like roughness, pothole and patching, ravelling, edge breaking and surface cracking. In the fourth stage, the secondary data like history of road maintenance, the maintenance strategies existing in the study area, the cost data for maintenance of study stretches and periodicity interval of maintenance were collected from the Highways Department, Tamilnadu. The climatic details were collected from the Meteorological Department of India and utilised in the current study. In the last stage, the analysis was carried out using HDM - 4 and optimum maintenance strategy was evolved. Study Area Description Chennai- the capital city of Tamil Nadu being the largest city in south India and one of the four metropolitan cities in the country is chosen as the study area. Chennai has been chosen as the study area as this study is proposed exclusively for urban roads and due to ease of availability of stretches in the nearby area. Preliminary Identification of Sites for Study Stretches > Stretches on flexible pavements with Bituminous concrete (BC) and Semi-Dense Bituminous Concrete (SDBC) surfacing. > Stretches on straight reaches and plain terrains with same rainfall conditions > Stretches without cross roads, cross drainage works and habitations. > Availability of data such as year of construction, crust details, traffic particulars, strengthening details, year of last renewal and specifications. > Stretches with uniformity in longitudinal and transverse directions with regard to crust composition, sub-grade, drainage and surface conditions to the extent possible. Finalisation of Study Stretches Having completed the preliminary identification of 36 stretches, the following data were collected on these stretches through field surveys and testing with a view to ensure uniformity in various characteristics of the stretches for the database development. Pavement Surface Condition The extent and type of distress developed in pavements were observed visually. The information on drainage, width of pavement, etc. were recorded Evaluation of Test pits Test pits of size 0.9m x 0.9m were dug, diagonally opposite on both ends of the identified stretches. The pits were under the wheel path at a distance of 0.5m to 1m depending upon the carriage way width, from the edge of the pavement. The pits were dug up to sub-grade level. The pavement was dug layer by layer. Thickness of each layer and the total crust were measured accurately. Stretches having substantially different composition and thickness were rejected. The following values of sub grade soil were collected from the Department records. > Field dry density > Field moisture content > Soaked CBR Pavement Evaluation In the selected study stretches, the following primary surveys were conducted for the requirement of HDM - 4 inputs. > Road Inventory Survey > Road Condition Survey > Traffic Survey Traffic Volume Survey The classified traffic volume surveys were conducted in all the 36 stretches in both directions during Feb'2009 and the details are given in Table 3. Road Condition Survey The following performance indicators were physically measured on the study stretches: > Cracking > Patches and Potholes > Ravelling > Roughness > Rutting > Edge breaking The results of distress survey are given in Table 4. Cost Data The cost data for maintenance of study stretches were collected from Highways Department, Tamilnadu and are shown in Table 5. Analysis Project analysis was carried out using HDM - 4 software with various maintenance options. The following maintenance options were considered in the analysis and the optimum maintenance option was identified by

4 34 STUDENTS PAPER COMPETITION 2009 Table 3 List of Study Stretches & Traffic Details S.No Name of the Road Section ID Chainage Age Length Traffic CBR AADT 1 Besant Nagar, 6th Avenue SI 0/50-0/ low Vandikaran street S2 0/200-0/ med Besant Nagar, 6th Avenue S3 0/570-0/ low furlong road S4 0/600-0/ Hev Besant Avenue S5 0/200-0/ med Indira Nagar, 2nd Avenue S6 0/200-0/ med Musirisubramaniam salai S7 0/350-0/ Hev Musirisubramaniam salai S8 0/50-0/ Hev Dr.Ranga Road S9 0/50-0/ med Venkateswara Agraharam Street S10 0/50-0/ low Greenways Road Sll 0/350-0/ med Gandhi salai S12 0/50-0/ med Besant Nagar, 3rd Avenue S13 0/200-0/ med Sringeri Mutt Road S14 0/250-0/ med R.A puram main road S15 0/50-0/ Hev R.A puram main road S16 0/350-0/ Hev South Canal Bank Road S17 0/50-0/ Hev South Canal Bank Road S18 0/700-0/ Hev Notron road S19 0/50-0/ low velachery main road S20 0/0-0/ Hev velachery main road S21 0/400-0/ Hev furlong road S22 0/50-0/ Hev Besant Nagar 3rd Main Road S23 0/50-0/ low C.v.Raman Road S24 I 0/50-0/ low R.R. Colony 1st Street S25 0/100-0/ med Besant Avenue S26 0/750-0/ med 'Feet Road S27 0/100-0/ Hev Devanathan Street S28 0/50-0/ Hev West canal bank road S29 0/350-0/ low West canal bank road S30 0/50-0/ low Indira Nagar, 3 rd Avenue S31 0/100-0/ med Besant Nagar, 7th Avenue S32 0/50-0/ med Mandhaveli Street S33 0/50-0/ med Kasturibai Nagar 3rd street S34 0/100-0/ Hev Kasturibai Nagar 3rd street S35 0/500-0/ Hev Indira Nagar, 1 st Avenue S36 0/200-0/ Med

5 PAVEMENT MAINTENANCE MANAGEMENT SYSTEM USING HDM-4 35 Table 4 Results of Distress Survey Section ID Drainage Carriage way(m) Roughness (m/km) Crack(%) Ravelling(%) No of Potholes No of Egdge Breaks Rut Depth (mm) Texture Depth (mm) S1 Good S2 Poor S3 Avg S4 Good S5 Avg S6 Good S7 Avg S8 Good S9 Good S10 Avg S11 Good S12 Good S13 Avg S14 Good S15 Good S16 Avg S17 Avg S18 Poor S19 Good S20 Poor S21 Avg S22 Poor S23 Good S24 Avg S25 Poor S26 Poor S27 Avg S28 Avg S29 Avg S30 Good S31 Avg S32 Poor S33 Poor S34 Avg S35 Good S36 good

6 36 STUDENTS PAPER COMPETITION 2009 Table 5 Cost of Maintenance Works SI. No. Type of Maintenance works Cost of works (Rs /sq.m) Economic cost Financial Cost 1 20 mm Premix carpet (PC) mm Semi Dense Bituminous Concrete (SDBC) mm Bituminous Concrete (BC) mm Dense Bituminous Macadam (DBM) Pothole patching Crack sealing Edge repair Source: Highways Dept, Tamilnadu (2008) considering the criteria of economic indicator, called NPV/CAP ratio. Option 1 - Do Nothing Option 2 - Routine Maintenance Option 3 - Overlay 25 mm SDBC Option 4 - Overlay 40 mm BC The NPV/CAP ratios for various options arrived are given in Table 6 and it can be seen that option 3 is yielding maximum NPV/CAP ratio for the stretches. Hence option 3 (i.e.,) overlay with 25mm thick SDBC is found to be optimum maintenance strategy. The average roughness of roads in the study stretches is shown in Figure 1. The roughness value exceeds the permissible IRI value of 4 in two years. Hence it may be concluded that the optimum periodicity interval for the maintenance strategy is 2 years. Fig 1 Average Roughness of study stretches predicted by HDM-4 Conclusions The following conclusions are drawn, from the field study and HDM - 4 analysis. > Maintenance treatment with 25mm SDBC is found to be optimum for the urban roads. > Average periodicity interval required for renewing the road surface is 2 years. However it varies for 2-10 years for the individual roads. Table 6 NPV/CAP ratio for various alternatives Section Option Option Option Option ID SI S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S32 0 o S S S S

7 PAVEMENT MAINTENANCE MANAGEMENT SYSTEM USING HDM-4 37 References Hernan de Solminihac.T (1996), Calibration of Performance Models for Surface Treatment to the Chilean conditions The HDM-4 case, Transportation Research Board and National Research Council, Washington R. Ul-islam, M. Nozawa, N. Ooguri and K. Tsunokawa (2002), A Preliminary Calibration Exercise of HDM-4'S Road User Effect Relationships for Japanese Conditions, Department of Civil & Environmental Engineering, Saitama University, Japan. Gary Chai(2000), Long Term Pavement Performance Study in Southeast Queensland, Malaysian Road Conference, Malaysia, 16-18, August Neethu Roy, Dr.kuncheriap.Isaac and Dr.A.Veeraragavan (2006), "Sensitivity Analysis of Input Parameters for Application of Highway Development and Management Tool (HDM-4) for Investment Decisions", Indian Highways, January 2006, ppl5-19. S.S.Naidu, DrP.K.Nanda, Dr P.K. Kanchan and K.Sitaramanjaneyulu(2005), Pavement Maintanance and Management System for Urban Roads using Software HDM-4 a case study, Indian Road Congress, Vol.66.3, pp S.SJain, Sanjiv Aggarwal and M.Parida (2005), HDM-4 Pavement Deterioration Models for Indian Highway Network, Journal of Transportation Engineering, Vol.131, pp Daba S. Gedafa (2006), Present pavement maintenance practice: a case study for Indian conditions using HDM- 4. Fall Students Conference, Midwest Transportation Consortium. G Morosiuk, T Toole (2002), Modeling the Deterioration of Bituminous Pavement in Indonesia within a HDM-4 Framework, Transport Research Laboratory. Christopher.R.Bennet, William.D.O (2000), HDM-4 volume -5 Aguide to Calibration and Adaptation.