Constructability (Value engineering)

The objective of this procedure is to make optimum use of development knowledge and experience in planning, design, procurement, and field operations to achieve overall project objectives. A common view of design guidelines involves only:

• Determining more efficient methods of development after initiation of the project;
• Allowing development personnel to review engineering documents periodically during the design phase;
• Assigning development personnel to the engineering office during design; and
• A modularization of pre-assembly program.

In fact, each of these represents merely a part of the optimization process. Yet only through effective and timely integration of development input into planning, design, and field operations will the potential benefits of optimization be achieved.

The planning/execution phases for a typical major project involve conceptual engineering, detailed engineering, procurement, development, and start up. Development optimization analysis should begin during the conceptual stage, at the same time as operability, reliability and maintainability considerations surface. It can then continue through the remaining phases. Planners must recognize that the payoff for optimization analysis is greatest in the earliest phases of a project, growing progressively less, but never ceasing, until the end of the project. In modern engineering jargon this process of design optimization is called constructability.

Constructability

Constructability analysis is a form of both Value Engineering (VE) and Value Analysis (VA) that focuses mainly on the development phase. Constructability decisions are oriented toward:

• Reducing total development time by creating conditions that maximize the potential for more concurrent (rather than sequential) development, and minimize rework and wasted time;
• Reducing work-hour requirements by creating conditions that promote better productivity or creating designs that demand less labor;
• Reducing cost of development (and tools) by reducing requirements for such equipment, creating conditions that promote more efficient use of the equipment, and minimizing the need for high-cost, special purpose equipment;
• Reducing materials costs through more efficient design, use of less costly materials, and creation of conditions that minimize waste;
• Creating the safest work place possible, since safety and work efficiency go hand in hand; and
• Promoting total quality management (TQM)

Essential Elements of Constructability

Three elements must be present if a constructability program is to realize its full potential.

First          

Constructability must be viewed as a program that requires proactive attention. The mistaken idea that constructability is a review of designs by someone familiar with development is totally wrong. By the time designs are ready for review, it may be too late to change anything, and, if such changes are made, they will be costly.

Instead, individuals with a knowledge of development must jointly participate with the other interested parties-owner, engineer, operator, and maintainer- to brainstorm concepts and approaches before they are committed to a drawing. In other words, constructability is a component of planning that must be included in all phases.

Second

Constructability is a team effort. Only if the interests of all parties are jointly represented in all decisions will the optimum solution be realized. Reducing development costs is certainly an important objective, but doing so must not compromise other needs.

Third

Constructability must have management commitment and support. The time and resources needed for such a program must be made available if the program is to be a success.

A Constructability Program

While no single approach will fit every program, the consensus is that most successful constructability programs have the following elements:

• Clear communication of senior management's commitment to the program;
• Single-point executive sponsorship of the program;
• An established policy and program, as well as tailored implementing phases for each project;
• A database compiling "lessons learned and examples;
• Orientation and training as needed; and
• Active appraisal and feedback.

Constructability Culture

Constructability works best when it is an accepted part of the way an organization operates. If the subject is given enough emphasis and attention over time, it becomes ingrained within the organization reaching what it can be called a constructability culture. Every staff person must feel part of the system, since their input is frequently sought in constructability brainstorming session and their ideas are welcome additions to the database.

Constructability Concepts

The Management Approach

Recognize that startup and development drive engineering and procurement scheduling.

• Develop a network schedule as early as possible; and
• Include engineering and procurement packages in the control schedule.

Use contracting and management approaches that promote development efficiency.

• On engineering-procurement-development projects executed on a fast-track basis (overlapping phases), use single management of the total effort from the outset of conceptual engineering;
• Use development contract packages of a quality that will allow fixed-price bidding as a means of reducing or eliminating the problems associated with changes;
• Do not start on a work package until the availability of all required resources is assured (personnel, materials and support equipment.);
• Work with the owner to use any existing facilities or services rather than creating duplicate ones for the development period;
• When packaging designs for specialty subcontracting, consider normal jurisdictional lines so that packages logically fit the specialty contractors involved and do not require sub-tier subcontracting;
• Plan the release of contracts to take advantage of favorable development weather;
• Provide adequate planning time for contractors and subcontractors in the bidding-award process;
• Keep the control schedule at a summary level;
• Ensure that project milestones are reasonably attainable considering both development and procurement time;
• Do not impose unnecessary hold points for quality checks;
• Keep requirements for owner involvement in the project(such as reviews and approval) to a minimum;
• Issue instrumentation, piping and insulation packages as early as possible, since these require the most field time to execute; and
• Use a contract form that incorporates incentives designed to reduce development costs. For example, include Value engineering (value analysis) clauses that provide for sharing in savings engendered by adopting cost improvement suggestions made by the contractor;

Ensure that project requirements and conditions are understood.

• Make certain that field conditions are accurately reflected on design documents;
• Identify all access routes and any limitations on their use;
• Be sure that all parties understand their roles and responsibilities with regard to providing equipment, the use of project areas and facilities, security and gate control, administrative policies, etc;
• Identify disposal areas for excavations, vegetation, non-hazardous waste and hazardous waste; and
• If working in or adjacent to an operating facility, identify all constraints that the situation presents.

Design Phase

Emphasize standardization and repetition.

• Standardization and repetition maximize application of the learning curve to the work force, allow volume buying of materials, and simplify purchasing and warehousing.
• Standardize structural members, foundations, bolt sizes, and other components as much as possible;
• Dimension concrete components to take advantage of readily available commercial form sizes; and
• Repeat designs throughout the facility. This will reduce design costs while promoting the learning curve effect during development.

Take maximum advantage of readily available, off-the-shelf materials and components.

• Maintain access to commercial catalogs of equipment and materials;
• Make maximum use of vendor representatives to assist in item selection;
• Survey the area to determine which materials are most readily available locally;
• Require procurement specialists to publish bulletin on a regular basis, identifying materials and items in short supply on the world market and approximating order-ship-deliver lead times of all equipment and materials regularly used in the contractor's work; and
• Consider using pre-engineered structures in lieu of specially designed structures.

Choose configurations that facilitate or simplify handling and erection.

• Require design engineers to develop recommended development methods and include them with the design. This will force them to think constructability.
• When designing steel members and connection, remember that erection is much easier if a member to be connected to another can be temporarily positioned on top of the in-place member or on a pre-installed seat on that member before bolting or welding.
• Take advantage of modularization. Vendor-assembled modules are produced under more favorable conditions than those in the field. This ensures better quality while reducing field erection time.
• Use designs that employ pre-cast concrete components which can be cast in a controlled environment, delivered to the project when needed without intermediate handling, and directly installed.
• Avoid components that require special care and handling in the field.
• Create designs not requiring special care and handling in the field.
• Include special foundations in the design o structures for mounting climbing cranes and elevators if such equipment will be used during development.
• Locate heavy and/or bulky items within structures so that as many as possible can be hoisted from a single location of the lifting equipment.
• Maximize the use of straight runs and perpendicular tie; avoid curves (particularly complex curves) and angles.
• Consider limitations of standard transport and lifting equipment when designing components. If necessary, design over-size items so they can be fabricated, transported and erected in parts.
• Use designs that minimize the need for temporary structures such as forming, shoring, bracing, and tie-downs.
• For multiple electrical and piping systems, consider using common utility tunnels, trays, or conduits through which multiple system can be installed (and easily removed or expanded later if necessary) rather than using direct embedment or multiple conduits.
• For multiple foundations in the same are, establish the same bottom elevation for all foundation so that excavation can be handled on a mass basis rather that individually.
• Design engineered items so that they can be dressed out on the ground for installation. In other words, design any components that cross several items (such as ladders or raceways) so portions of them can be pre-assembled with the engineered item to create a module.
• Design electrical/instrumentation connections with plug-in configurations rather than a labor-intensive connection.
• For complex wiring networks, specify the use of wiring harnesses that are factory assembled and coded.
• In lieu of cast-in-place reinforced walls, consider using the lift-slab technique.
• On multi-storied buildings with reinforced concrete floors, consider casting the floors one at a time on the lower deck and lifting them into position. This will eliminate many bracing and scaffolding requirements.
• In lieu of specifying concrete block wall using conventional masonry techniques (mortar between blocks), specify simple stacking of blocks followed by plastering of both sides with fiber-reinforced mortar. The result is a better-looking, stronger wall that can be constructed more quickly by less skilled personnel.
• When designing connections for hydraulic or other systems, create unique designs for each category of connection to avoid any potential for connection mixups in the field.
• When designing or specifying large components (such as vessels or rotating equipment), include lifting hooks or other handling devices/features in the design so field erectors will not have to improvise the rigging and handling.
• Provide designs for special measuring devices, templates, or other erection aids that may be useful for aligning or achieving tolerances.

Create designs that promote accessibility and provide adequate space for development personnel, material, and equipment.

• Consider interstitial designs for buildings. This means providing space above all operating floors that is zoned for various operating systems. The vertical clearance in this space should be enough to allow for easy movement of workers. This design greatly simplifies development, and facilitates future maintenance and upgrading.
• Locate electrical pull boxes with adequate space around them to simplify cable pulling.
• Size pipe racks to allow easy addition of new lines.
• Incorporate access openings in both exterior and interior walls.
• Provide for reasonable working space around all installed components.