A Computer Model for Selecting Equipment for Earthmoving Operations Using Simulation paper

Ain Shams University, Faculty of Engineering

Ain Shams Journal of Civil Engineering(ASJCE)

Vol. 1.No.1, March, 2009, pp.203-214

A Computer Model for Selecting Equipment for Earthmoving Operations Using Simulation

K.M.Shawki*; A.M.Ragb** ,H.K.Eliwah***

*Assistant prof., College of Engineering and Technology, AASTMT, Alexandria, Egypt.** Associate prof., College of Engineering and Technology, AASTMT, Alexandria, Egypt.***M.Sc. College of Engineering and Technology, AASTMT, Alexandria, Egypt.

ARTICLE HISTORY Received: Accepted

ABSTRACT

Earthmoving is often one of the most important operations in many construction projects in terms of its great effect on costs and productivity. In this paper we propose a simulation decision supporting model using PROEQUIP to assist engineers and decision makers to select the appropriate earthmoving operation and to control and record earthmoving productivity and cost. For this purpose, a graphic and analytic model that represents the earthmoving productivity was idealized. Data were collected concerning a real case, followed by several simulations aiming at the identified operational scenarios. As a conclusion of the study, PROEQUIP model provide an important instrument for decision makers when managing earthmoving planning and execution .

Keywords

Construction ,equipment, production , simulation

Earthmoving refers to all the operations involving the cut, loading, haulage, unloading, grading and compaction of materials in a civil engineering projects. To improve earthmoving planning, a variety of methods and techniques has been tried. Planners have relied upon three methods to estimate productivity: historical data; references, such as equipment handbooks;

particular methods such as construction simulation or statistic analysis.In 1968 the Caterpillar Tractor Company developed a graphical model for solving the machine matching problem by analyzing machine output. Also the Queue theory will be used as the controlling tool for checking the accuracy of number of allocated equipment and the effect of any changes in number of equipment on the project duration.

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The history of Queue theory goes back to 1909. In this year A. K.Erlang, a Danish engineer, studied the Queue systems and waiting time in telecommunication systems. In 1953 David G. Kendall formulated the Queue theory to the form known today and showed the empirical applications of this theory for different problems. The first book discussing the basis and applications of Queue theory issued in 1958 by Philip M. Morse. The main components of Queue system are interiors (customers) and service suppliers. In the truck filling and refilling problem, the trucks are assumed as the customers of Queue system. Hoes are known as service providers in this system. One hoe along with specified number of trucks is known as a Queue system. The objective of solving this problem is to determine the number of trucks that serve one hoe. Applications of simulation techniques to earthmoving operations were made in the 1960s. Willenbrock (1972) developed a model using a computer simulation language, GPSS (General Purpose Simulation System), to estimate cost for earthworks.Simulation has been used extensively in many areas of Construction Engineering starting with the introduction of CYCLONE by Halpin (1977). This methodology has been considered as the basis for a number of construction simulation systems. AbouRizk and Shi (1994) developed an optimization model that considers only the quantities of resources being used along with their respective user-specified boundaries. Special purpose simulation (SPS) was proposed by AbouRizk and Hajjar (1997) to address the stated issues. The idea is to develop user friendly simulation tools native to the application domain itself. In (2007) Bruno, Ernesto and Giovanni propose a model using Stochastic Colored Petri Nets to represent the operational dynamics of earth moving work. Finally in (2008) Raj Kapur, Nashwan and Serafim Castro presented a new method for

integration of ((variable productivity)) data with a visualization model of earthwork operations.

1. EART MOVING FUNDAMENTALS

In order to understand the true benefits of an automated earthmoving simulation system such as PROEQUIP, it’s important to present some background information about the processes involved and the traditional method of preparing project estimates. Earthmoving is a specialized construction field where large quantities of earth are moved from one location to another location. Earthmoving projects consist of many interacting processes including preparation, loading, hauling and dumping. Loading is the process of transporting earth from the prepared earth pile into incoming trucks. This is done using hauling equipment such as hoes. Hauling involves trucks traveling through roads with varying slopes and ground conditions in order to transport earth and return. Dumping is the transfer of earth from the trucks into a spreading pile. The travel velocity of trucks is dependent on the grade and rolling resistances of a given road segment. Grade resistance is a measure of the force that must be overcome to move trucks over uphill slopes. Rolling resistance is a measure of the force that must be overcome to roll or pull a wheel off the ground.

2. SYSTEM DESIGN

The input data are one of the most important aspects in the implementation of any modeling and simulation study. In order to calculate and compare production and cost rates between several different models, a great deal of time could be spent on the necessary calculations. The computer modeling and simulation system was designed to facilitate this process. Microsoft Visual Basic.Net was chosen as main programming language to develop the main system PROEQUIP.

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Microsoft Excel – powered by crystal ball tool - was chosen for simulation calculation by integration with the main system. The User Interface is divided into seven sections. In the first section the user may insert the data about studied project. In second section (see Figure (1)) the user may insert the data about excavation job. Third section required user to insert the data about the hauling road surface. In section four (see Figure (2)) the user may

choose a single model from the database of all available trucks. This section also allows user ability to add, edit or delete models to/from database. In section five and section six the user may insert the data about the equipment costs. Section seven (see Figure (3)) is for the simulation, the user may choose a model from the database of all available trucks for simulation calculation. The User interface

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contains links to the traditional and simulation results.The software rolling resistance has been integrated with a Microsoft Access database of soil properties, road condition and trucks to facilitate calculation using equation during programming. The Soil Properties database contains the table of available types of earth to be moved – 23 types of materials are listed -. This database lists the weight per BCM (Bank cubic meter) and per LCM (Loose cubic meter), bucket fill factor and the excavator cycle time for each type. The Road Conditions database contains a table which lists the types of haul roads from which the user can choose – 21 types of roads surface are listed -. The table also lists the rolling resistances for these road types.Finally there is a database contains a list of trucks. Each record in this database consists of the model, horse power, empty weight, payload, top speed at loaded and heaped capacity. There are also a database tables for job efficiency factors. The users can add new truck from the main interface (see Figure (2)). This option facilitates addition of a new truck into the database.

The output section contains three parts: deterministic performance result, simulation result and recommendations page. The output of the first part - by clicking on the “RESULTS” button – may use as a productivity monitor and control. It show the production by LCM (Loose cubic meter) per hour, BCM (Bank cubic meter) per hour or LCY (Loose cubic yard) per hour, BCY (Bank cubic yard) per hour, cost per hour, cost per LCM … etc, number of buckets, number of trucks need to result the maximum production, maximum truck speed loaded and empty (starting speed) at haul travel and (end speed) at return travel, project duration per hour and per day and expected finish date. This section is shown in Figure (4).

3. THE SIMULATION

Simulation has been utilized to capture the dynamic behavior and the characteristics of the process being modeled. It is a proven technique for the planning of construction projects. Construction operations are frequently impacted by uncertainties and characterized by dynamically shared resources. Accordingly, simulation is considered a potent modeling technique to capture their essential characteristics. Considerable efforts have been made to develop general simulation languages to model these operations. In this paper during simulation process, when a truck enters a road segment, it is randomly assigned a travel speed based on the speed study data to find a travel time by equations. The input data to be used in the simulation program have been taken from literature values that are most commonly used and from site researches. The parameters which had been used for the random variables are arbitrarily assumed and are given in Table (1). The truck and excavator unit cost random range variables have been selected to be inserted by the software user because the natural of the unit cost and its changes according to variable conditions.The following basic modeling assumptions are made in the proposed simulation program are as follows:.1. All trucks in the project are identical – for each case - (i.e. their capacities, horse power, speed, etc are the same).2. To use the results for more than one excavator in the project, all excavators in the project should be identical in terms of their loading capabilities – for each case - (i.e. they have the same probability distribution types and same parameters for loading process).

3.The project haul roads are designed to provide two-way traffic for the trucks.

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4. The excavator must complete loading for the truck before start loading another truck 5. Single material type is assumed for the simulation program and all trucks in the project dump their loads at the same dumping site.6. All trucks start operation at the parking area near the hauling point at the start of the shift and park there at the end of each shift.

7. During a simulation run, the haulage system is performing without any rest (i.e. eight hours per shift).8. Up to five earthmoving cases can be compared during simulation.

Because the random variables may change every trip during the job, all simulation trials just simulate project job until it finish for one time then it record productivity, unit cost and duration, those trials have been repeated x

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times. The user can select the proper number of trials according to the required accuracy of the results. The trip trials has been designed for 1,000 m3 excavation quantities jobs, but the results will be fit for more than 1,000 m3

quantities jobs. To facilitate the mathematical logic which has been used in the simulation, see the proposed flowchart that included in Figure (5).

4. PROEQUIP VERIFICATION

To verify PROEQUIP model, a solved example is performed. The problem data are as shown in Table (2) and data used for estimating equipment cost are as shown in Table (3).

Table (4) shows the comparison between output data from the solved example and resulting from PROEQIP model. One can see that the output data from PRTOEQUIP and the solved example are identical.

The results of the two cases of study are shown in Figures (6, 7, 8 and 9). Figures (6 and 7) show the maximum production for each of the proposed scenario. Form this figures we can obtain the scenario which gives the maximum production. Figures (8 and 9) shows the cost of each of the propose scenario which we can get the case that gives minimum cost

5. IMPLEMENTATION

In order to demonstrate PROEQUIP capabilities, two case studies of projects will be performed using particular project conditions.

5.1 CASES FOR STUDY

The description of the first case study is shown in Table (5). The available company trucks are as shown in Table (6). Also the

equipment available trucks for renting are as Table (7). The available company excavators are as shown in Table (8). Also the excavators available for renting are as Table (9).The description of the second case study is shown in Table (10). The available company trucks are as shown in Table (11). Also the equipment available trucks for renting are as Table (12).From Figures (6 and 7) we can recognize that case 4 in first case of study gives maximum production and minimum cost for earthmoving. The fleet configuration consists of Kumatsu PC210 LC crawler excavator and Scania 113H trucks as hauling units. The same for second case of study shown in Figures (8 and 9). 6. CONCLUSIONS

This paper presents a computer model “PROEQUIP” for equipment fleet selection for earthmoving operations using simulation. The developed system is designed to assist engineers, owners, and contractors for earthmoving projects in selecting the best equipment fleet that can complete the task in maximum production and minimum cost. It also provides fleet production rates, cost for each fleet, number of buckets, number of trucks, maximum speed of trucks for hauling and return, project duration and project expected finish date.

REFERENCES

1. Hassan Eliwah, "Earthmoving Productivity and Cost Estimating Using Computer Modeling and Simulation", M. Eng. thesis, Arab Academy for Science and Technology and Maritime Transport, Alexandria, Egypt, 2010.

2. Caterpillar. "Caterpillar Performance Handbook", ed. 36th. Caterpillar Tractor Company, Peoria, Illinois, USA, 2006.

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3. Peurifoy, P.E./Schexnayder, P.E "Construction Planning, Equipment, and Methods", ed. 6th. McGraw-Hill, Inc., New York, N.Y., USA, 2002.

4. S. M. Karamihas and T. D. Gillespie, “Characterizing Trucks for Dynamic Load Prediction”, Heavy Vehicle Systems, Vol. 1, No. 1, USA, 1993

5. James York and Tom Maze, “Applicability Of Performance-Based Standards To Truck Size and

Weight Regulation in The United States”, Road Transport Technology, 4: Proceedings of the Fourth International Symposium on Heavy Vehicle Weights and Dimensions, Ann Arbor, 1995.

6. Amirkhanian , S.N., and Baker, N.J. "Expert System for Equipment Selection for Earth-Moving Operations", ASCE, Journal of Construction Engineering and Management, Vol. 118, No. 2, New York, N.Y., USA, 1992.

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7. Hanna, A. “SELECTCRANE: An Expert System for Optimum Crane Selection” Proceedings on the 1st Conference of Computing in Civil Eng., USA, 1994

8. AbouRizk, S.M., Shi, J., “Automated Construction Simulation Optimization”, Journal of Construction Engineering and Management, ASCE, USA, 199

9. Christian, J. & Xie, T.X. “Improving Earthmoving Estimating by More Realistic Knowledge.” Canadian Journal of Civil Eng., Canada, 199

10. AbouRizk, S.M. and Hajjar “Applying Simulation in Construction”, Submitted to the Canadian Journal of Civil Engineering, NRC, Canada, 1997

11. McCabe, B., “Belief Networks in Construction Simulation”, Proceeding of the 1998 Winter Simulation Conference, ed., D.J. Medeiros, E.F. Watson, J. S. Carson, and M.S. Manivannan, 1279-1286. Institute of Electrical and Electronics Engineers, Piscataway, New Jersey, USA, 1998.

12. Naoum, S. and Haidar, A. “A hybrid knowledge base system and genetic algorithms for equipment selection”, Engineering, Construction and Architectural Management, 7(1), USA, 2000

13. Kannan, G., Schmitz, L. and Larsen, C. “An industry perspective on the role of equipment

based earthmoving simulation”, In Proceedings of the 2000 Winter Simulation Conference, USA, 2000

14. Bruno, Ernesto and Giovanni Cordeiro “A Stochastic Colored Petri Net Model To Allocate Equipments For Earth Moving Operations”, ITcon Vol. 13 (2008), Prata et al, pg. 490

15. Frank Harris "Modern Construction and Ground Engineering Equipment and Methods", ed. 2nd. Longman Group, United Kingdom, 1994.

16. FAO Co., “Cost Control in Forest Harvesting and Road Construction”, Food and Agriculture Organization of the United Nations, Rome, 1992

17. Hesham Rakha, Ivana Lucic, "Variable Power Vehicle Dynamics Model for Estimation Truck Accelerations", Journal of Construction Engineering and Management, ASCE, USA, 2002

18. Ivana Lucic, "Truck Modeling Along Grade Section", M. Eng. thesis, Virginia Polytechnic Institute and State University, Virginia, USA, 2001.

19. Douglas D. Gransberg, "Optimizing Haul Unit Size and Number Based on Loading Facility Characteristics", Journal of Construction Engineering and Management, ASCE, USA, 1996

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ملخصالبحث

و حفار من مكونة معدات لمنظومة للحفر التكلفة و االنتاجية دراسة إلى البحث هذا يهدف

المحاكاة باستخدام االتربة نقل سيارات من برنامج . SIMULATIONمجموعة اقتراح وتم

هذا PROEQIP حاسب يتضمن و المقاوالت، شركات و التشييد لمهندسي االستخدام سهل

و المعدة نوع حيث من الحفر معدة مواصفات في تتمثل المدخالت من مجموعة البرنامج

بشاشة موضحة المعلومات من اخري مجموعة و التحميل زمن و بالقادوس الخاصة السعة

نوع مثل االتربة نقل بسيارات الخاصة بالمواصفات البرنامج تزويد تم ايضا و االستخدام

بشاشة االخري المواصفات بعض الي باالضافة حجما و وزنا المقررة الحمولة و السيارة

السيارات. تسلكة سوف الذي الطريق مواصفات علي ايضا البرنامج يحتوي كما البرنامج

المعدات . تشغيل باسعار خاص جزء علي ايضا البرنامج يشتمل و العمومية المقالب الي

بحساب البرنامج قيام الي باالضافة للحفر تكلفة افضل حساب من المستخدم يتمكن حتي

. بقاعدة البرنامج تزويد تم االنتهاء تاريخ و الحفر اعمال لنهو الالزمة التشغيل ساعات عدد

اي . اضافة المستخدم يستطيع كما التربة نقل سيارات و الحفارات انواع عن معلومات

. البرنامج يتميز المعلومات قاعدة في جودها و عدم حالة في المعدات عن اخري معلومات

. تم البحث هذا في التكلفة و االنتاجية في تتمثل التي المخرجات قراءة بسهولة المقترح

. و التشييد مواقع من لموقعين حفر تكلفة اقل مع انتاجية اقصي لحساب البرنامج استخدام

المعدات استخدام مجال في الصحة و السالمة عن ارشادات بجزء البرنامج تزويد تم اخيرا

التشييد مواقع في و خاصة المعدات استخدام مجال في المهنية الصحة و السالمة الهمية

عامة.

Figure (1) User interface – Job information

Figure (2) Model database

Figure (3) User interface – Simulation section

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Figure (4) The production and cost results page

Figure (5)- The simulation model pseudocode

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Figure (6) The simulation overlay charts for all study cases


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Table (1) Parameters for the Random Variables Used in the Models

Random VariablesMin. Value

Max. value

meanstandard deviation

Type of distribution

(Figure 8)Notes

Excavator cycle time (Sec.)

10 40 25 9.49 Normal

Truck speed loaded (km/hr)

10 By userauto

BetaAlpha = 3Beta = 1Truck speed empty

(km/hr)20 By user Beta

Dump time (min.) 0.30 2.50 1.40 0.68 Normal

Unit cost By user auto Normal

Table (2) Articulated Truck and road configurations for example 1 Truck Gross power = 309 hp

Truck Net empty weight = 22,260 kg

Truck Payload = 23,590 kg

Truck Top speed loaded = 56.8 km/hr

Truck heaped capacity = 14.4 m3

Excavator heaped capacity = 1.9 m3, and its cycle time = 23 seconds

Quantity of excavation material = 20000 m3

Project work 8 hours per day and 6 days per week

Road (smooth roadway - rolling resistance = 1.5%) with 90 km/hr legal speed

Haul material (dry clay - loose material weight = 1480 kg/m3),

The haul road from the borrow site to the dump is 4 km uphill grade of 2%

Job efficiency = 50 minutes per hour = 0.83

Excavator engine power = 115 hp

Table (3) Cost data for example 1 Truck purchase price = 850,000 LE

Truck Salvage price = 200,000 LE

Excavator purchase price = 450,000 LE

Excavator salvage price = 90,000 LE

Interest rate = 5%

Taxes rate = 9%

Insurance rate = 6%

Operator cost = 6 LE/hr

Helper cost = 4 LE/hr

There are 3 helpers

Cost of fuel per liter = 1 LE

Truck tire cost = 1000

Engine type is diesel

Site condition: shallow depth excavation, high safety and good management at

site (ownership period = 25,000 hrs for truck & 12,000 hrs for excavator (ZONE

A))

Table (4 ) Results of model testing

ParametersSOLVED

EXAMPLEPROEQUIP

Actual Production (LCM/hr) 211.02 LCM/hr 211.044 LCM/hr

Truck speed loaded (km/hr) 55.52 km/hr 55.52 km/hr

Truck speed empty (km/hr) 90 km/hr 90 km/hr

No. of required trucks 4 trucks 4 trucks

No. of buckets per truck 8 buckets 8 buckets

Earthmoving system unit cost (LE/hr)

683.44 683.47

Table (5) The description of the first case study

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Project name: GAZADCO SHRIMP FARM EXPANSION

Project location: Jizan, Kingdom of Saudi Arabia

Excavation material type: Wet clay

Project Area: 910,000 m2

Area of the study part of the project: 75,000 m2

Quantity of excavation for project: 1,816,331 m3

Quantity of excavation for the study part of the project:

150,000 m3

Distance from site to dump: 9000 m

Number of simulation trials: 5000 trials

Table (6) Available company trucks

S.N Type (Model)Payload (ton)

Heaped capacity (m3)

Number available

Equipment cost (SR)

T1 Mercedes Benz 3328K (1987) 18.5 16 8P = 419,000S = 65,000(62.58 +- 10% SR/hr)

T2 Mercedes Benz 2638 (1993) 19 13 6P = 280,000S = 50,000(50.20 +- 10% SR/hr)

T3 Mercedes Benz 2635 (1991) 20 14 8P = 297,000S = 50,000(51.89 +- 10% SR/hr)

T4 Volvo – FM12.420 (2004) 19.2 14 13P = 507,000S = 45,000(73.37 +- 10% SR/hr)

T5 Mercedes Benz 2628(1983) 18.96 15 14P = 318,000S = 45,000(54.57 +- 10% SR/hr)

Table (7) Equipment available for renting (Trucks)



Number available

Equipment unit cost (SR/day)

RT1 Mercedes Benz 4143 (2003) 19 13 8 600 - 680

RT2 Mercedes Benz 4037 (1997) 19 12 4 560 - 620

Table (8) Available company excavators

S.N Type (Model)Heaped

capacity (m3)Number

availableEquipment cost (SR)

E1 Hyundai R140 LC – 7 1.5 1P = 310,000S = 90,000(96.46 +- 10% SR/hr)

E2 Caterpillar 325 DL 1.9 1P = 390,000S = 100,000(110.40 +- 10% SR/hr)

Table (9) Equipment available for renting (Excavators)

S.N Type (Model)Heaped capacity (m3)

Number available

Equipment unit cost (SR/day)

RE1 Kumatsu PC240 LC 1.5 1 680

RE2 Caterpillar 225 1.3 1 680

Table (10) The description of the second study case

Project name: Increase (Kabary/Matrooh) railway efficiency

Project location: Marsa Matrooh - Egypt

Excavation material type: Sand

Project Area: 28 km'

Area of the study part of the project: 5 km'

Quantity of excavation for project: 25000 m3

Quantity of excavation for the study part of the project:

4000 m3

Distance from site to dump: 4000 m

Number of simulation trials: 5000 trials

Table (11) Company Equipment (Trucks)

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Number available

Equipment cost (EGP)

T1 Mercedes Benz 3331 19 12 11P = 520,000S = 100,000(98.80 +- 10% EGP/hr)

T2 Scania 113H 14 10 5P = 400,000S = 100,000(84.75 +- 10% EGP/hr)

Table (12) Equipment available for renting (Excavators)

S.N Type (Model)Heaped capacity (m3)

Number available

Equipment unit cost (EGP/day)

RE1 Kumatsu PW160-7 wheeled 1.0 1 700

RE2 Kumatsu PC210 LC crawler 1.3 1 800

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A Computer Model for Selecting Equipment for Earthmoving Operations Using Simulation paper