Contract documents for a construction project consist primarily of the agreement, conditions of the contract, drawings and specifications, and any addenda issued to clarify, or modify the bidding or proposal documents before the contract for construction is signed. As such, construction drawings and specifications are parts of the legal documents of the agreement that are issued to delineate the requirements regarding the materials, products, systems, installation guidelines and procedures, standards and workmanship, and quality aspects involved with the execution of the work. This short article identifies some of the design-related factors that may result in change orders.
Defective specifications are examples of design-related issues that may result in contract modifications. An owner may specifically direct a contractor to make changes to the contract scope of work if it finds out that the specifications are defective. It is more likely, however, that defective specifications result in constructive changes. Incomplete or inaccurate specifications are examples of defective specifications.
Here are examples of changes that may occur due to design-related reasons:
Changes due to incomplete specifications: If specifications provide insufficient information necessary to implement the work outlined in the contract, they are considered incomplete. In addition, if specifications provide inadequate information in coordinating construction details between different design disciplines (e.g., structural, mechanical, electrical), specifications are considered incomplete. A complete set of specifications are intended to provide adequate information necessary to execute the work to achieve the project objectives set forth in the contract.
Changes due to design discrepancies: If the construction drawings associated with different trades are inconsistent, a design discrepancy exists between contract documents. In addition, differences and discrepancies among plans, specifications, and details or discrepancies between planned and actual equipment details may be indicative of design discrepancies that need to be rectified by issuing proper change orders.
Changes due to physical or technological constraints: Specifications may also be considered defective if a project design does not provide adequate space for fitting all the elements or does not meet physical or technological constraints that need to be considered in design and construction. Depending on the level of complexity of the issue, site conditions, and other technical and contractual requirements, resolving such issues may require changes in design, modification of requirements, and subsequently making minor or major adjustments on-site where appropriate.
Changes to satisfy regulatory requirements. Design documents are supposed to satisfy the requirements of applicable codes, standards, and regulations. Therefore, if the project team finds out that the project scope of work needs to be modified to properly satisfy regulatory requirements, a change order may be needed to ensure the requested change is properly reflected on design documents and implemented to satisfy regulatory requirements.
Latent conditions: Some changes are made due to differing site or subsurface conditions, unknown at the time of bidding. They are conditions within the project site that are materially different from what was shown on the contract documents or those that substantially differ from conditions that are obvious and apparent.
Other changes that occur due to design-related reasons may include changes due to a change in needs and expectations, changes made to address value engineering concerns, and modifications due to technology-related needs, and those due to errors and omissions. It is important to identify, properly document, and control changes over the course of projects to ensure project scope is managed in an effective manner, and to ensure time and cost overruns arisen from scope-related issues are minimized.
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One of the factors with adverse effects on labor productivity is shiftwork. Shiftwork is defined as working other than regular daytime hours. Shiftwork is the most commonly utilized alternative to overtime; however, these two methods may be used together so that segregating the two may not be straightforward. It is also important to note that overtime and shiftwork adversely influence productivity in a generally similar way.
When work is performed on a shiftwork basis, labor productivity is adversely affected because of reasons such as stress on circadian rhythms, additional resource or preparation needs, or other factors such as additional coordination, labor, and supervision. These factors need to be considered when work on a shiftwork is scheduled to ensure informed decisions are made.
One of the key issues with shiftwork is its adverse effect on circadian rhythms. Circadian rhythms are the approximate 24-hour variations in bodily functions in individuals. The key cyclic changes that occur in bodily functions in individuals include sleep patterns, blood pressure, heart rate, and core body temperature. Bodily functions tend to increase right after awakening, increase in midafternoon, and then steadily decrease in the middle of the night. As such, those who need to perform on a shiftwork basis typically experience a degradation in performance.
Although the body of those individuals who perform on a shiftwork basis tend to adapt to night work, the circadian rhythm does not in fact completely shift and bodily adjustment periods tend to be long. Some indications that may suggest shiftwork has adversely affected an individual’s body include higher rates of accidents and error in performing tasks, fatigue, appetite loss, increased sickness rates, digestive problems, and other health problems.
Consequences of shiftwork are not limited to those effects that adversely affect the circadian rhythms of individuals who perform on a shiftwork basis. Other issues with shiftwork include the following:
1- The adverse effects of shiftwork on social interactions and negative effects on family life of those who perform on a shiftwork basis.
2- Dilution of supervision typically occur as a result of shiftwork because the supervising team may not use the same working pattern than the working pattern used by shift-working individuals.
3- Challenges in exchanging performance information among individuals who work in different shifts.
4- Higher work setup times. Different shift-working teams tend to work with the same set of tools, machinery, and equipment; therefore, work setup times are typically higher when multiple teams (instead of one team) use the same set of tools, machinery, and equipment. In addition, extra time is needed in shiftwork for the process of hand-over and transition from one shift to another.
5- Work environment considerations: Since shiftwork is performed in hours other than daytime hours, work environment considerations need to be identified. Examples include natural lighting vs. artificial lighting and additional demands for air conditioning.
All of the above-mentioned factors adversely influence work performance in performing tasks that are implemented on a shiftwork basis. Moreover, successful implementation of the work that needs to be performed on a shiftwork basis typically requires additional resources to accommodate the shift project. Additional resources that are generally needed to support shiftwork can be categorized into the three main categories of labor, supervision and job-specific costs. Each of these categories are further discussed in the following:
1- Labor needs
Shiftwork typically requires hiring of additional personnel; however, it is important to note that, because of the learning curve effect, the efficiency level of new hires are typically lower than the efficiency of the current team members. In addition, employers need to pay for shift premium differentials, as needed. Other labor-related considerations that need to be given to shift-working include long bodily adjustment periods, especially for those individuals who are not used to shift-working, higher accident and error rates in performing shiftwork, higher likelihood of improper alcohol consumption before or during shiftwork, and poor attitude towards shiftwork.
2- Supervision needs
Adequate supporting and supervisory personnel are needed when a work is performed on a shiftwork basis. Establishing relationship between work shifts and proper hand-over process between shifts are also important to ensure the work smoothly progresses across different work shifts.
3- Job-specific needs
Examples job-specific needs that have to be evaluated include safety requirements, higher demands for air conditioning or heat equipment to perform shiftwork, and adequacy of equipment, tool, machinery, and material to ensure enough resources are available on-site to make progress as expected.
A number of studies address the adverse effects of shiftwork on productivity. Some of the key studies include the Bureau of Labor Statistics, the Business Roundtable, NECA 1969 study, and the Construction Industry Institute (CII). The American Association for Cost Engineering (AACE) has identified some of the recommended specialized studies that can be used to evaluate the adverse effects of shiftwork on productivity (AACE, 2004). AACE categorizes the specialized studies related to overtime and shiftwork into the same category because these two areas overlap and the adverse effects of overtime and shiftwork on productivity are similar
One set of models that are often used to assess the adverse impact of shiftwork and/or working overtime on labor productivity is the work of Hanna and Haddad (2009), which is a modified version of the NECA study. The work of Hanna and Haddad (2009) proposes using macro and micro approaches. The macro approach is used for projects in which no specific overtime schedule is used whereas the micro approach is used in projects in which a fixed overtime schedule (e.g., such as six 10 hour days per week throughout a certain number of weeks) is utilized. Both models indicate that as the number of weekly hours worked increase, the labor productivity declines. The following two figures illustrate these two models:
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(Adapted from the work of Hanna and Haddad (2009))
In Figure 1 a regression line is fitted to the data which plots the performance factor index (i.e., earned hours / actual hours) against the total hours worked per week. Figure 2 plots productivity against the number of weeks in which a fixed overtime schedule (e.g., such as six 10 hour days per week throughout a certain number of weeks) is utilized. Since this model uses Measured Mile Method (MMM) to calculate productivity loss in periods with and without overtime, the outcomes of the model are shown as MMM. These outcomes are compared against the NECA 1969 study.
In sum, shiftwork is one of the methods that are used to accelerate projects. It is important to note, however, that, similar to working overtime, shiftwork has adverse effects on labor productivity. Some of the key issues with shiftwork include its adverse effect on circadian rhythms, dilution of supervision, challenges in exchanging performance information among individuals who work in different shifts, the adverse effects of shiftwork on social interactions, and higher work setup times. The methods used to assess the adverse effects of shiftwork on productivity overlap with the methods used to evaluate the loss of labor productivity due to overtime because the adverse effects of overtime and shiftwork on productivity are similar.
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A variety of reasons may cause an increase or decrease in the amount of work from the scope of work specified in the original contract. These reasons result in either directed changes or constructive changes to the project’s scope of work. This article briefly describes each of these main categories of changes. It also outlines the potential implications of changes to a contract scope of work from the time, cost, and productivity perspectives.
In general, owners have the contractual right to make changes to the scope of work outlined in the original contract. Since owner changes impact contract scope of work and they potentially have time, cost, and productivity implications, it is important to identify various types of change in project scope of work and recognize potential effect of each type of change on project contracts. Examples of the most common changes include:
Changes in means and methods or material to be installed
Differing site conditions not envisioned in the original contract price
Modifications that change the planned work sequence as originally envisioned
Changes to the scope of work due to constructability issues or conflicts between systems
Changes in construction, prescriptive, proprietary, or performance specifications
Corrections made due to errors or omissions
Modifications as a result of the actions or inactions of third-parties
A directed change is issued when the owner specifically directs the contractor to make a change. This type of change may or may not affect the contract price. A directed change that influences only the schedule is an example of a directed change with no effect on the contract price. As another example, a directed change that impacts a project’s configuration, work sequence, or space requirements may adversely influence labor and equipment productivity on-site. A directed change with cost impact may reduce or add the contract price. Directed changes are typically not complicated because the owner specifically directs the contractor to make a change and as such, directed changes are easier to recognize.
Constructive changes, on the other hand, occur as a result of non-owner-directed events that implicitly necessitate modifying the scope of work. Unlike directed changes, the owner does not specifically direct the contractor to make a change in case of a constructive change. Instead, as a result of non-owner-directed events or actions or inactions of the owner, the contractor is forced to modify the scope set forth in the contract. Typically, constructive changes are not easy to recognize because they generally occur due to non-owner-directed events or circumstances. In addition, in case of a constructive change, the owner does not typically have explicit acknowledgment of a change to the original scope of work set forth in the contract. Examples of the most common types of constructive changes include:
Verbal communications that implicitly necessitate making changes
Deficient drawings or specifications
Ambiguity in architect-provided responses to information requests
Differing site conditions
Over-inspection
It is important to identify changes in a timely manner, especially in case of constructive changes whose effects are not explicit and readily recognizable. The reasons for each change need to properly be identified and documented in proper change management logs. Moreover, the effects and implications of each change need to properly be documented to ensure sufficient documentation and historical records are readily accessible to substantiate contractual entitlements. If your project has been affected by multiple change orders and they have adversely affected labor or equipment productivity on-site, or if you are interested to investigate the extent of time and cost impacts due to change orders, Adroit will be able to assist in assessing these impacts. For more information, please contact us.
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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.
An Example Work Breakdown Structure of a 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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A Work Breakdown Structure (WBS) provides a hierarchical or a breakdown structure that decomposes the project scope into more discrete and manageable work components [1]. The process of breaking down the scope into a WBS should continue until the entire project scope is decomposed in adequate details matching the level of control that the project team wants to exercise.
WBS breaks down the entire project scope into meaningful components. WBS is a key project artifact that provides a basis for project planning, performance measurement, and project control. It also creates common language among the project team members and stakeholders to ensure everyone is using the same terms in referring to specific parts of the project scope.
Contrary to the popular belief that only one WBS should be developed for each project, it is suggested that two WBSs be produced to define a project scope: a deliverable-oriented WBS and a process-oriented WBS [2,3]. These two work breakdown structures are different but they are not produced independently of each other. Developing and using these two key types of WBS has certain benefits that justify the efforts to produce these two artifacts and use them in tandem.
A deliverable-oriented WBS (also known as product-oriented WBS) decomposes the project scope into smaller and more manageable deliverables. Deliverable are tangible components that need to be delivered to complete the project. They are typically a physical component or an item that needs to be produced, obtained, or supplied as a result of executing project activities. These deliverables are either interim or ultimate deliverables that are delivered to satisfy project requirements. In construction projects, preliminary plans and specifications, bid documents, and pre-construction mockups are example interim project deliverables. Example of ultimate project deliverables in a construction project may include concrete structures, structural steels, building facade, and a building’s mechanical system.
WBS elements in a deliverable-oriented WBS are typically in the form of a noun because WBS elements identify tangible components that are typically a physical item that needs to be produced, obtained, or supplied. A verity of breakdown criteria can be used to develop a deliverable-oriented WBS to meets the specific needs of projects. For example, a construction contractor may breakdown its scope of work based primarily on physical locations of different project components; whereas, a mechanical contractor may use a system-wise approach to identify systems, sub-systems, and lower level components in each subsystem to decomposes its scope of work. The following figure provides an example deliverable-oriented WBS for a residential project.
An Example Deliverable-Oriented Work Breakdown Structure (WBS) for a Residential Project
A process-oriented WBS, on the other hand, defines the project scope of work in terms of process steps (i.e., work phases, or functions)[5]. A process-oriented WBS defines what process steps need to be taken to deliver each of the project deliverables. WBS elements in a process-oriented WBS are typically in the form of a verb. They may also identify different work disciplines that are involved to work on various project deliverables. Example WBS elements in a process-oriented WBS include engineering, detailed design, procure, install, and construct. These WBS elements are provided in a hierarchical structure to breakdown the project scope into different functions or process steps. For example, a WBS element such as install may need to be broken down into mechanical and electrical installation depending on a particular project’s scope of work and the scope of responsibilities of the party that is developing the WBS. The following figure provides an example process-oriented WBS for a piping project.
An Example Process-Oriented Work Breakdown Structure (WBS) for a Piping Project
It is important to properly develop project work breakdown structures by choosing proper breakdown criteria, selecting meaningful WBS elements, and using proper level of breakdown to ensure a) project deliverables are properly identified and organized in a hierarchical structure b) work processes are identified in an appropriate fashion to ensure project team members have the same understanding of what needs to be done from a work process or functional perspective to deliver each project deliverable. Developing both deliverable-oriented and a process-oriented WBSs also helps project teams to better identify project activities.
To learn more about project work breakdown structures and the way project management professionals can use the full potential of work breakdown structures, please contact us.
References:
[1]. Project Management Institute. (2013). A guide to the project management body of knowledge (PMBOK guide). Newtown Square, PA: Project Management Institute. ISBN: 9781935589679
[2]. Golpayegani, S. A. H., & Emamizadeh, B. (2007). Designing work breakdown structures using modular neural networks. Decision Support Systems, 44(1), 202-222.
[3]. AACE International®. RP 33R-15 Developing the Project Work Breakdown Structure, AACE International®, Morgantown, WV, USA
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Our posts to the Insights page share fresh insights and seasoned advice about many project and construction management topics. To have the Insights monthly newsletter delivered automatically to your email inbox, please subscribe here.
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.
Subway station rehabilitation / renovation projects (hereinafter referred to as subway rehabilitation projects) are among the projects with special needs [1] in which a variety of stakeholders including the Department of Transportation (DOT), Department of Environmental Protection (DEP), Department of Historic Resources (DHR), utility companies, regulatory organizations, municipalities, and community organizations are usually involved. Some rehabilitation projects interfere with daily operations at stations; therefore, specific execution strategies such as diverting trains and working in confined spaces are required for successful completion of these projects. Execution of these strategies usually requires proper management of project-specific constraints, assumptions, and objectives and being equipped with a right set of skills and knowledge.
Subway rehabilitation projects have special characteristics which differentiate them from other types of construction projects. The most important characteristics of subway rehabilitation projects from a project planning perspective are shown in the figure below.
Key Planning and Scheduling Considerations for Subway Rehabilitation Projects
Maintaining the reliability of the existing railway transit system while following safety and punctuality guidelines is an important factor that needs to be accounted for. According to the study performed by Collins and Rowe [2], some of the unique considerations of transit projects are as follows:
Acquisition of right-of-way
Acquisition of special services
Relocation of utilities
Relocation of construction infrastructure.
These requirements are all applicable to subway rehabilitation projects; hence, they should be addressed in such a way that the typically large number of private and public stakeholders remain satisfied with the project. Based on the foregoing, it is important to investigate planning and scheduling requirements of subway rehabilitation projects to ensure these projects are executed efficiently and delivered per expectation. The following section describes special characteristics of subway rehabilitation projects in more depth:
Special services are among the distinct aspects of subway rehabilitation projects. It is important to identify different types of special services that are commonly used in these projects. The following provides a brief explanation of some of the special services frequently encountered on subway rehabilitation projects:
Diversions
Subway projects often require temporary service diversions due to interference with normal train operations. A diversion occurs when a train changes its track in a station (e.g. from a local track to an express track); whereas, a by-passing occurs when a train passes a station through its normal tack of service and without any stop. Some tasks can be performed during a by-passing, however, some tasks such as working on tracks need diversion.
Public transit systems constantly try to maximize the productivity of tracks and minimize track outages and passenger inconvenience; therefore, service diversions for maintenance, emergencies, and special events are costly and not easily coordinated. Before approving any diversion requests, all impacts (i.e., definitive and potential impacts) on the affected tracks need to be closely analyzed by the planning and operations departments; therefore, detailed planning for each diversion is of great importance in advance of subway construction, rehabilitation, or renovation projects.
Depending on the project type, location of the station, and daily average subway ridership in the station, the following considerations need to be taken into account for diversion planning:
Permissible days and hours of work during each service diversion
Number of diversions provided within a month and during the construction phase
Timeframes during which no diversion is available (e.g., holiday seasons)
Work restrictions during diversions
A so-called piggy-back diversion is scheduled when a project utilizes the available diversion opportunities of another project or a maintenance task. Piggy-backing has several benefits including:
Utilization of available diversions
Maximizing track access productivity
Minimizing track access schedule conflicts
Reducing customer inconvenience
Reducing the project expenditure
For planning of subway projects with multiple diversions, the during-diversion work should be broken down into scopes of work scheduled for each diversion based on each diversion’s calendar, sequence of activities, and open (i.e., available) work-fronts. With this method of planning, contractors and owners will be able to analyze the number of diversions required to complete the project and assess the feasibility of the tasks scheduled for each diversion. This method of planning also helps contractors make timely requests for adequate work-trains and services they need.
Efficient utilization of diversions is a crucial factor to consider in time and cost management of subway rehabilitation projects. To reduce costs and inconvenience of passengers, the activities that require a diversion should be scheduled together to the extent possible [3]. That being said, safety should not be compromised by stacking several trades in limited areas. In addition, it should be noted that inefficient use of diversion opportunities usually result in deviations from plans and cause disputes and unexpected losses.
Flagging
Some tasks that are performed on or under the tracks or in close proximity with the platforms (i.e., close to train tracks, or in certain heights above the platform) may require flaggers. Construction flaggers signal approaching trains to slow down and warn project personnel of oncoming trains. Some activities such as working on elevators, mezzanine areas, or street entrances are executed without a need for diversion and flaggers; however, some activities are planned either with service diversions or under traffic with flagging protection (i.e., without suspension of train services). Examples of activities that require flagging include surveying operations, inspections, and activities that require work- or test-trains. Operations departments usually prefer activities to be executed under traffic with flagging rather than having activities performed with diversions. Nonetheless, flagging is costly and clients and contractors typically try to minimize the use of flagging. The following steps should be performed before requesting flagging:
Identify the tasks that require flagging and determine the timeframes during which flagging is required;
Calculate the numbers of required flaggers for each task.
Determine the total number of flaggers required for each event.
Specify the flaggers’ working hours.
Consider alternative methods for minimizing the number of required flaggers. Some alternative methods include but are not limited to barricades, safety railings, and barricaded scaffolds.
Analyze the sequence of the tasks that require flagging to check if they can be done sequentially – doing so may decrease the total number of flaggers required for each event.
Work-Trains
In subway rehabilitation projects, work-trains with special equipment (such as crane and scaffold) are sometimes required. Since work-trains of a company are usually enterprise-wide resources that are shared among multiple projects, issuing timely requests and accounting for a reasonable lead-time to acquire work-trains is paramount. Some companies have guidelines for requesting and proper scheduling of work-trains as part of their enterprise resource planning system. Project planners should familiarize themselves with their company’s equipment request procedures. The following considerations need to be taken into account for requesting work-trains:
The number of required work-trains during each planning timeframe
Safety considerations in scheduling activities that involve the use of work-trains
Required modifications/additions to work-trains (e.g., mounting work platforms or cable reels)
The amount of material to be transported by each work-train
The number of required round trips
The required equipment for and the party responsible for loading/unloading work-trains
The allowable hours and locations for loading/unloading operations
The possibility of using other projects’ idle work-trains.
Conclusion
Subway rehabilitation projects have unique characteristics; and various uncertainties exist in these types of projects. Some special characteristics of subway rehabilitation projects include the need for work-trains, diversions, flaggers, and utility relocations. Keeping various stakeholders (e.g., local communities, operation and maintenance departments, utility agencies, and environmental agencies) satisfied over the course of the project is also extremely important.
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