When it comes to managing projects, Parsons Brinckerhoff (PB) is no stranger to controversy. Here is another screwup of a project involving PB, and this one could be very costly:
Metro could walk away from the troubled Silver Spring Transit Center if it isn’t satisfied with repairs Montgomery County will have to make to the $112 million bus-and-train hub, an agency spokesman said Wednesday.
Metro was supposed to assume control of the three-level structure at least two years ago. But an engineering report released Tuesday found the facility unusable and unsafe in its current condition, plagued by design and construction errors that led to cracked, inadequately strengthened concrete. The opening, delayed several times, has been postponed indefinitely, as officials devise a plan to address the problems.
“If we’re not satisfied [with it] we won’t accept it,” said Dan Stessel, Metro’s chief spokesman and director of communications. “If the facility is not safe or there are issues regarding its long-term maintainability, we have the right to not accept it.”
Parsons Brinckerhoff provided on-site construction project management, with responsibility for site structural inspection. As noted in the report:
PB’s structural engineer visited the site and reviewed the area of a pour before the pour for a number of deck pours and in each case, PB’s structural engineer eventually signed off on them (we can only find eight such reports for the eighteen post‐tensioned deck pours, including subpours, in the information provided).
There are notations in the RBB reports of cold joints forming in the concrete as shown in jobsite photographs (Attachment 13) (i.e., concrete hardening not at a pre‐planned joint) without indications as to the resolution of those unplanned joints, only that stressing was delayed.
In the information provided, we can only find PB approval of formwork removal and stressing record review for limited pours.
We can find only one inspection report in those supplied with notation of formwork inspection required of RBB, and then without detail.
Despite Project requirements, we can find no record of measurement of slab thickness, in situ clear cover determination, or of the deck finishing process in the RBB reports presented to us. We can find only several notations in the RBB daily reports regarding the concrete curing process used as to methods and/or time, and only limited records of in situ concrete deck temperatures. Also, there are no notations as to above slab wind break installation. We found no RBB inspection reports of the installation of the evaporation retarder called for or the curing compound called for, nor for any deck curing methods used in the non‐winter months.
There are several Project photographs that show workers using procedures that are not approved for winter concreting. Attachment 14 shows a worker spraying something, presumably an evaporation retarder or curing compound, on the concrete slab while walking on it. Another photograph shows a worker using a Rosebud acetylene torch (Attachment 14A) in an apparent attempt to heat epoxy‐coated reinforcing before a pour. In a third photograph, a worker is apparently applying some type of deicer on the reinforcing steel. During the period 10/02/10‐10/05/10, cracks began appearing in slabs in areas where no stressing had not yet occurred.
There is an expansion joint called for on the Contract Documents in the center of the ellipse at each side. The distance to the temporary Pour Strip on the East and West end is approximately 240 feet on the centerline of the radius and another 40 feet (280 feet total) on the outside radius. (A Pour Strip is an area of a slab left out during construction and then placed after adjacent concrete has been poured and has had an opportunity to shrink. It is not an expansion joint.) We would note the as‐designed Pour Strips themselves are substantially wider than the normal 3‐4 foot Industry Standard.
Read the entire report at: report-structural-evaluation-of-superstructure.
Read Full Post »
Systemic Failure 