Comparison between Critical Path Method (CPM) and Last Planners System (LPS) for Planning and Scheduling METRO Rail Project of Ahmedabad

Viraj Parekh1 , Karan Asnani1, Yashraj Bhatt1 and Rahul Mulchandani1

1 Civil Engineering Department, Institute of Technology, Nirma University, Ahmedabad, India

Abstract. The purpose of this paper is to compare Critical Path Method (CPM) and Last Planner System (LPS) with respect to Planning and Scheduling of METRO Rail Project, Ahmedabad, Gujarat. Critical Path Method emphasises on updating the network for tracking the progress as well as to identify the delays. Last Planner System works on the weekly schedules prepared from the Master Plan and Look-ahead schedules to avoid the delays. One of the stretch from North-South Corridor was selected for the study from Vijaynagar to Usmanpura. The data such as activities, duration of activities, sequence and inter-relation of activities etc. were collected to prepare the network as well as weekly schedules. The network was updated and original network was compared with the up- dated one and the delays were spotted for the stretch selected. Weekly plans were also prepared for the selected stretch from the look-ahead schedule and Master Plan. PPC (Percent Plan Complete) were calculated to track the progress as per planned schedule. The data were collected by conducting interviews of various personnel and visual obser- vations. Both the approaches (CPM and LPS) have been applied on the selected stretch by action research process. The delays were calculated and studied for both the methods and it was observed that Last Planner System is more appropriate to use for big infra- structure projects like this to avoid time-overrun and consecutive cost over-run. Re- sources can be well utilized with the Last Planner System, too. The type of this paper is a Case Study.

Keywords: Construction Planning and Scheduling, Last Planner System, Con- struction Project Management

1 Introduction

Planning and Scheduling is the back-bone for any Construction Project as execution is purely based on the planning and scheduling. If Planning and Scheduling is done haphazardly then execution of the project will be affected and the project would observe time overrun and consecutive cost overrun. Critical Path Method (CPM) and Program Evaluation and Review Technique (PERT) are being used for planning and scheduling in the construction industry since last 5 decades. Over the period of time, certain limi- tations of CPM and PERT was observed. Though the network representation in CPM and PERT is an integral part of Project, Last Planner System aids in better clarity about the work on executional basis.

© Springer Nature Singapore Pte Ltd. 2020 519 C. Ha-Minh et al. (eds.), CIGOS 2019, Innovation for Sustainable Infrastructure, Lecture Notes in Civil Engineering 54, https://doi.org/10.1007/978-981-15-0802-8_81 520 V. Parekh et al.

A Network is created in Critical Path Method connecting all the activities. Forward Pass and Backward Pass gives the Critical Path of the Network. All the activities lying on Critical Path are considered as Critical Activities; having float value zero. Rest of all the activities are considered to be non-critical activities. When the project is not executed as per the planned schedule, Critical Path of the Network may get changed. In that case, certain activities may become critical which were non-critical earlier. Change in Critical Path and Critical Activities disturb the entire planning and schedul- ing with respect to time, resources, cost, etc. and it can be considered as the major limitation of Critical Path Method. Once the original schedule gets disturbed, it is very difficult to bring back on track and the project observes time overrun and cost overrun. Last Planner System (LPS) was developed to increase the effectiveness of planning and control by making programmes more predictable, thereby improving the chances of delivering them on time [1]. The LPS has been implemented in a large number of projects in several countries since 1992 [2]. Many reports and research papers have confirmed that the technique has achieved remarkable improvements, including better planning and control, improved work flow reliability, increased productivity, promo- tion of team building; improved quality and safety, enhanced predictability, thereby reducing the duration and cost of projects (e.g. [3], [4], [5], [6], [7] and [8]). The liter- ature, however, shows no evidence of LPS practical applications within India as well as on METRO Rail Projects. Therefore, this study is concerned with the application of LPS in METRO Rail Project of Ahmedabad in the state of Gujarat, India. The study also compares the traditional method of planning and scheduling CPM with LPS re- garding the METRO Rail Project of Ahmedabad. Ahmedabad Metro is an under construction mass transit system being built for the Ahmedabad City. It is being built by Gujarat Metro Rail Corporation (GMRC) Limited; a Special Purpose Vehicle constituted to implement all the Metro Projects in the state of Gujarat. The total length of the Ahmedabad Metro Rail Project (Phase-I) is about 40.03 km out of which 6.35 km is underground tunnel construction and the rest is ele- vated construction. The project will connect 4 corners of the Ahmedabad city with 2 corridors (North-South and East-West) and 32 stations.

2 Methodology

Feasibility study for the Ahmedabad METRO Rail Project was done two times. Therefore, since beginning of the project, delays were observed. In such situation, plan- ning and scheduling of the project must be thorough to reciprocate the delays. To pre- pare the planning and scheduling of METRO Rail Project, data collection was done at the first place. Data was collected by interviewing respective personnel of METRO Rail Project. List of Activity, Duration of Activity and Interdependency was collected for the stretch of Vijaynagar to Usmanpura in North-South Corridor. Based on the collected data presented in Table 1, a network was prepared (Fig.1). Duration was calculated from the Network and that came as 42 days. The Network was updated after 28 days and updated network was also created. By performing forward pass and backward pass in the updated network, the duration on critical path was calculated and it came to be