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.
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.
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.
References:
[1]. M Mirhadi Fard, Planning and scheduling requirements of subway station rehabilitation/renovation projects, AACE International’s 2016 Annual Meeting, Toronto
[2]. Collins, J., Rowe, J., Management Challenges Unique to Transit Projects. AACE® International Transactions PM. 15, 2005.
[2]. Budai, G., Huisman, D., and Dekker, R., Scheduling preventive railway maintenance activities, Journal of the Operational Research Society 57: 1035–1044, 2006.
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