Dr. Maryam Mirhadi, PMP, PSP
This article is part of a technical article, entitled Planning and scheduling requirements of subway station rehabilitation/renovation projects, that Adroit’s competent professionals have authored and presented in AACE International’s 2016 Annual Meeting in Toronto.
As discussed in previous articles, subway rehabilitation projects have special characteristics; therefore, some considerations for scheduling these projects shall be applied with special attention and emphasis [1]. The following provides key considerations for planning and scheduling of these projects:
Constructability and phasing Review
Constructability and phasing review in early stages of work (i.e., design phase) is an important aspect of time management for subway construction projects. The constructability and phasing review should cover the entire project scope and be done in such a way that the number of required diversions (occasions for service interruption), work-trains, and flaggers be minimized. The following figure provides an example work breakdown structure for s subway rehabilitation project.
Constructability review is a construction management technique that reviews construction processes to minimize design errors, ambiguous specifications, costly, difficult-to-bid or difficult-to-implement features [2,3,4]. Constructability and phasing review helps the stakeholders to study the feasibility of the execution plan and to ensure that the project can be completed either with safe and continuous operation of trains or during planned diversions. In some cases, the constructability study may result in design changes to make the construction phases feasible. One of the key outputs of the constructability and phasing review process is the list of constraints that should be taken into account during construction.
To efficiently develop the phasing plan, the project team should consider various factors including, but not limited to:
- The activities that cannot be executed during normal service hours (i.e., the activities that need diversion of train services) should be identified. Examples include activities on the platform edge and activities on, under, or near tracks. If a project involves working on several stations on the same line, the stations that are between two immediate switches can utilize the same diversion (by piggy-backing on each other). Under these circumstances, diversion-related tasks should be scheduled properly to maximize efficiency.
Having multiple diversions on one line and between different switches is called double-heating. If the stations are not between two immediate switches, diversions are not usually scheduled at the same time to avoid double-heating and ensure train service interruptions are minimized.
- The preliminary number and type of the required diversions, work-trains, and other special services for the project should be determined.
- The special services identified should be reviewed with operations departments to ensure availability. If the requested diversions cannot be accommodated during required timeframes, the scope of work, design requirements, alternative construction methods, job phasing, or the project timeline should be reviewed and revised based on the available diversion plans. In addition to time, budget, and resource constraints, the availability of diversions is one of the major constraints that impact subway rehabilitation projects.
- In each subway station, the project team needs to identify the areas and equipment that cannot concurrently be closed or taken out-of-service to ensure of continuous and safe operation of the station. Examples include entrance stairs, platform stairs, mezzanine areas, elevators, and tracks. For instance, if there are two elevators in a station and upgrading both elevators are in the project scope of work, working on the two elevators at the same time may not be permitted.
- Some old subway stations may contain hazardous materials such as lead, asbestos, and mercury. As such, performing abatement operations might be necessary before the commencement of work in certain areas. In these cases, direct communication and coordination between the client, contractor, and environmental agencies is crucial to identify proper course of actions. In addition, removal of these material during the construction phase may require special permits and equipment for which contractors should plan in advance.
- The long-lead and client-furnished items should be identified.
- The activities that are supposed to be executed in areas that are under the authority of other agencies need to be identified. Examples include utility relocations or working in a public street. In addition, it should be determined if these activities require additional permits (e.g., DOT permits). The project team should be aware that these tasks have the potential to delay the project to a great extent because the project team usually has little control on expediting the permit application, inspection, or review processes.
Program management
One of the key inputs required to review/revise project prioritizations, manage workloads, and allocate shared resources (e.g., special services) is an integrated and enterprise-wide program control system. Having a centralized database to store project records not only facilitates decision making, but also increases the reliability of the decisions made. For this purpose, tools such as the enterprise-based Oracle® Primavera P6™ Professional Project Portfolio Management can be used [5]. Appropriate procedures should be in place to standardize input data from different departments and to ensure that project records are updated on a regular basis.
Considerations for special activities
The tasks that have special prerequisites or require special considerations should be identified in early stages of project planning. Examples include:
- Removing, repackaging, transportation, and disposal of mercury, lead, or asbestos. Containing materials may require acquisition of special licenses and permits. These permits should be considered as predecessors for related activities.
- Working in or impacting areas under the authority of other agencies may require permit acquisition. For instance, working in public streets or bringing heavy equipment to certain areas may need permission form the DOT; and obtaining these permits should be defined as a predecessor for related activities. The activities that impact or interrupt the operation services of equipment, systems, or utilities under the authority of other agencies, such as removing or placing a communication system need to go through a bulletin approval process. The purpose of bulletin is to support continued operations of the systems and equipment by having backup plans in place. The bulletin should be reviewed and approved by different client’s departments such as operations and planning, maintenance of way, and system safety groups. As such, the bulletin initiation and approval are prerequisites for the related construction tasks. The review and approval process should be initiated in a timely manner to ensure no delays occur.
- Working in historic areas: If the project scope involves working in historic areas of a station, special permits such as permits from the local historic preservation office may be required.
- Some activities such as utility relocation work may need to be performed by other agencies; therefore, it is important that the project team obtains sufficient information (e.g., forecasted start and finish dates or forecasted durations, calendars, constraints, execution plans, and intended activity sequences) about these activities to ensure possible conflicts can be resolved in a timely manner.
- Sometimes, subway rehabilitation projects require the acquisition or procurement of long-lead items (e.g., special signal equipment); therefore, it is important that planning and scheduling professionals timely start the process of obtaining long-lead items. They also need to perform periodic reviews to ensure that the delivery of the long-lead items are on schedule.
Calendar
Working days and shifts that are available for the scheduled activities and resource availability dates denoting when a resource is available for work on the project are to be revisited depending on the types of activities, timeline of receiving proper permits, timeline of diversions, interfaces with other agencies, locations where those activities are executed, and whether activities are performed in or impact other agencies’ areas of work.
For instance, the project team may need to modify the project working days and/or shifts based on the moratorium period and subway station service hours. Some diversions may be scheduled only for few hours, during night, or during weekends; therefore, the calendars assigned to related tasks should be set to hourly, nightly, or other calendar types as needed. Incorporating multiple calendars in project schedules is recommended to account for availability times for scheduled activities, project resources, agencies resources, special services (i.e., diversions in particular).
It is important to note that due to the nature of some subway rehabilitation projects, special services such as diversions, may become one of the key drivers of the project completion date. Special schedules such as look-ahead schedules with short time periods should be used in these cases to plan and monitor the project work at a detail level. Otherwise, unavailability of resources or special services may adversely affect service utilizations and result in significant delays and damages.
Considerations for updating schedules
Planning and scheduling professionals need to pay special attention to updating project schedules in subway rehabilitation projects (see AACE® International recommended practice 53R-06 [6] for minimum considerations for schedule update reviews). Updating schedules helps to determine remaining tasks or portions of tasks, identify the number and types of special services required to complete the projects, and update enterprise resource plans. It also helps clients minimize service diversions and maximize efficiency of planned services by what-if analyses, piggybacking, distributing resources, and re-phasing of projects. It is important to ensure that project schedules are developed and updated in such a way that no conflicts exist with pre-determined phasing restrictions and the schedule does not use more than the contractually agreed number of services.
Another important consideration for effective scheduling of subway rehabilitation projects is compatibility of look-ahead schedules with updated project control schedules (i.e., detailed schedules). Since look-ahead schedules highlight the near-term priorities and identify work-fronts, it is important that look-ahead schedules do not contradict updated project control schedules. Look-ahead schedules should be prepared based on and after adding more detailed scheduling information to project control schedules. On the other hand, if the contractor updates the look-ahead schedule based on the latest and up to date project information, the contractor should ensure that project control schedules are updated accordingly.
Determining activity durations
For estimating durations required for review/approval of contractor submittals by public transit companies, contractors need to consider sufficient time for all steps of the process including submission, review, resubmission, and approval steps. Following the guidelines provided in recommended practice 32R-04 [7] for determining activity durations is recommended to ensure all important considerations are taken into account. Sometimes, construction contracts define key expected durations such as maximum allowable duration for submission, review, and approval; therefore, it is important to review the contracts prior to developing project schedules.
Another important consideration for scheduling subway rehabilitation projects is inspection times. Inspections are among the special considerations for these types of projects and adequate durations need to be accounted for to ensure inspection times are not under-estimated during schedule development or updating processes.
Impact/delay analysis
Proper record keeping is important in contemporaneous cause-and-effect analysis of project changes and delays. Establishing an effective change management system will help to avoid unnecessary and costly investigations in case of any disputes. As soon as a change is introduced or an AWO is discussed, its impact on the project schedule should be investigated and outcomes need to properly be communicated with relevant parties in a timely manner. All assumptions and basis documents for impact analyses should also be properly recorded.
Conclusion
Subway rehabilitation projects have unique characteristics; and various uncertainties exist in these types of projects. Too many variables and uncertainties make time management of these projects challenging. Addressing the challenges in advance and effective risk response planning play important roles in successful execution of these projects. This article highlighted some the most important considerations for successful time management of these projects. Some of these considerations include constructability and phasing review, effective program management, considerations for special activities, considerations in the use of calendars, considerations for updating schedules, considerations in determining activity durations and in performing schedule analysis.
References:
[1]. M Mirhadi Fard, Planning and scheduling requirements of subway station rehabilitation/renovation projects, AACE International’s 2016 Annual Meeting, Toronto
[2]. AACE® International, RP 30R-03 Implementing Project Constructability, AACE® International, Morgantown, WV, USA.
[3]. AACE® International, RP 48R-06 Schedule Constructability review, AACE® International, Morgantown, WV, USA.
[4]. Construction Industry Institute (CII), Constructability: A Primer, Publication RS3-1 (July), CII, Austin, Texas, 1986.
[5]. Owen, JK, Criss, B., Managing Los Angeles $40 Billion Transportation Program with P6. AACE® International Transactions, PM.05, 2010.
[6]. AACE® International, RP 53R-06 Schedule Update Review— As Applied in Engineering, Procurement, and Construction, AACE® International, Morgantown, WV, USA.
[7]. AACE® International, RP 32R-04 Determining Activity Durations, AACE® International, Morgantown, WV, USA.
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