The Benefit of Constructability Reviews
Title: The Benefit of Constructability Reviews
Phase(s): Final Design
Date: February 16, 2001
The New Jersey Transit Corporation’s (NJTC) $69 million Hamilton Transit Transportation Complex is comprised of two components: a new, state of the art Bus Maintenance Facility (BMF) and a new Rail Station and 1600 car parking area.
The project delivery system was "traditional" design-bid-build, with all operational and management responsibilities by NJTC. Design of the project was initiated in 1994. Construction bids were opened in May 1996, and construction of the initial phase of the project, the BMF, was initiated in September 1996. The NJTC Project Manager assigned to the project during the design phase, advocated that a CR be performed in conjunction with design. However, a CR was not authorized for budgetary reasons. In addition, the construction management services for the project were competitively bid, but the CMC was not issued a notice to proceed until shortly after award of the construction contract.
The project was completed by the original completion date conveyed in the contract documents, November 1998. Although design omissions and change orders are anticipated throughout the life of a project, the volume of design omissions or changes required on this project appears to be greater than normal. The Project Management Oversight Consultant along with the current NJTC Project Manager and the CMC Resident Engineer concur that this project would have benefited greatly with a CR. Although the CMC was authorized to conduct an abbreviated CR just prior to the start of construction, the contractor noted the majority of the design omissions. Examples include:
- The site geometry of the BMF was conveyed inaccurately on the contract drawings, impacting quantities of sitework and utilities.
- Sprinkler design was not adequately presented to comply with local codes.
- Electrical requirements for owner supplied equipment was not conveyed on the drawings.
- Lack of coordination between plumbing and architectural drawings resulted in numerous inconsistencies.
- Fire protection/fire alarm systems did not meet with local codes.
- Conflicts between light pole foundations and large diameter pipes comprising the underground detention basins under the parking lots necessitated re-design.
Several of these items impacted elements of work on the critical path of the project. A secondary impact of the large volume of Requests for Information (RFI) submitted by the contractor was that the designer had to mobilize extra resources to investigate and respond to the RFI’s. For the first 6 months of the project, the turn around of RFIs was slow, resulting in frustrations among the designer, CMC, NJTC and the construction contractor. One of the most conspicuous topics at the two partnering sessions convened for the project dealt with improving turnaround of RFIs.
2. The Lesson
Minimizing design omissions should be a prime objective of construction management services rendered during the preconstruction phase of a design-bid-build project. If the grantee has its own resources, CRs can be performed "in house", in conjunction with the design review or value engineering of the designer’s plans. As an alternative if the grantee does not have the resource, it is recommended that the CMC be authorized to conduct a thorough CR, ideally prior to completion of the 50% design package. It is vital that, regardless of who performs the CR, attention is focused on the following elements:
- Coordination of drawings for each discipline (e.g., mechanical, electrical, plumbing, structural, architectural)
- Compliance with both federal (e.g., BOCA, ADA, APTA, ANSI) as well as state and local codes (e.g., DCA for NJTC).
- Accuracy of site geometry (e.g., compare building dimensions to dimensions derived form coordinates).
- Compatibility of specifications, with design drawings.
- Overall clarity of the drawings.
CR comments should be compiled and submitted to the designer. The designer should formally respond to each comment with a "status" designation (e.g., done, will comply, to be discussed, not applicable). Involving the CMC is the CR process enhances the CMC’s understanding of potential issues well before construction gets underway.
The benefits recognized from The CR process include:
- Reduced design omissions and, consequently, reduced change orders and time and cost impacts.
- Reduced volume of RFIs.
- Enhanced quality of the contract documents for bidding.
These comments and recommendations should be applicable to all rail transit facility construction projects, regardless of complexity or whether the construction is new or rehabilitation/modernization.