Analysis of Traffic Data Determination of Vehicle Damage Factor VDF

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CHAPTER 4 RESULTS AND ANALYSIS

4.1 Analysis of Traffic Data

In this study, analysis of traffic data in the means of calculating average daily traffic ADT was performed by summing all groups of vehicles for the entire survey period 24-hours a day and then divided on how many days to collect the 24-hour data. The data survey period was 5 days for each direction. However, the full-set data, i.e. 24-hour traffic data, available in this study was only 3 days. Therefore, all traffic analyses in this study were based upon these 3-day traffic data. According to Bina Marga standards 2009, vehicles could be categorized into 7 classes, however, only three classes of vehicles categorized as truck-type heavy vehicle that were considered in this study, in accordance with 1993 AASHTO Design Guide requirement. They are vehicle-class of 6B for 2-axis trailer, 7A for 3-axis trailer and 7C for more than 3-axis trailer. Vehicle-class 7C consists of three sub-classes; they are 7C1 for 4-axle trailer, 7C2 for 5-axle trailer and 7C3 for 6-axle trailer. The ADT of heavy vehicles for both directions for three-day survey is as shown in Table 4.1 below. Table 4.1: ADT for Heavy Vehicles Direction ADT of Each Vehicle Classes and Sub-classes vehicle 6B 7A 7C Total 7C1 7C2 7C3 Demak – Trengguli 921 781 74 130 119 2,025 Trengguli – Demak 814 968 83 146 134 2,144 Source: Bina Marga 2009 From the table above, it can be seen that there is relatively no much deviation of ADT for heavy vehicles for both direction. 27

4.2 Determination of Vehicle Damage Factor VDF

VDF or axle load equivalency factor LEF or E of each heavy vehicle was determined using 1993 AASHTO Design Guide procedure, as follows. 1. The axle load unit was converted from ton to kips and the type of the axle load was determined whether it is single, tandem or triple axles. 2. VDF or E was determined by correlating the axle load see the first column of Tables 4.2, 4.3 and 4.4 for single, tandem and triple axles, respectively and its corresponding VDF value see the rest columns of the tables. The selected VDF was the value under pavement structural number SN equals to 5, as recommended by 1993 AASHTO Design Guide. In this study, all axle load equivalency factor tables were associated with terminal serviceability p t equals to 2. 3. The VDF of front and rear axles for every type of heavy vehicle were calculated based upon the configuration specification defined by Bina Marga 2009 4. The VDF for each heavy vehicle was determined by summing its corresponding front and rear axles. Then, the total VDF for each type of heavy vehicle could be calculated. The results for VDF for each type of heavy vehicle are shown in Table 4.5. The sample of VDF calculation can be seen in Appendix D. 28 Source AASHTO 1993 Source: AASHTO 1993 Table 4.3: Table 4.2: 29 Source: AASHTO 1993 Table 4.3: 30 Source: AASHTO 1993 Table 4.4: 31 Table 4.5: Total VDF for Each Type of Heavy Vehicle Used in This Study As seen in Table 4.5, the total VDF of Demak – Trengguli direction is higher than the opposite direction. The deviation of VDF is mainly contributed by VDF of classes 6B, 7C1 and 7C3.

4.3 Calculation of Traffic Load