Study Cites ‘Inappropriate’ Procedure in Subway Work : Construction: Outside firm hired by MTA criticizes the use and installation of wood wedges in tunnels.

The substitution of wood wedges for metal bracing in 12 miles of Los Angeles subway tunnels under construction was “inappropriate,” according to an outside engineering study performed for the Metropolitan Transportation Authority.

The study, obtained Wednesday night, also concluded that the wedges in tunnels along Hollywood Boulevard failed two months ago mainly because the contractor did not install them properly and did not surround them with concrete or grout material as required.

The findings present the MTA with a critical portrait of the design and construction of the twin tunnels being built in Hollywood and under Vermont Avenue. Excavation in Hollywood has been halted since Aug. 18, when surface sinkages of nine inches were confirmed. Two days later, workers were evacuated from one tunnel because of fears that the structure could collapse.

Transit authority Chief Executive Officer Franklin E. White hired the Chicago-area forensic engineering firm of Wiss, Janney, Elstner Associates this month to provide an independent analysis of the construction overseen by MTA engineers and consultants.

White, reached Wednesday night, said he will weigh the report in deciding what, if any action, to take against the MTA’s design engineering consultants, led by the firm of Parsons Brinckerhoff.

“That is a matter we will be pursuing . . . with the design team,” White said. “Were we to conclude that professional standards were not met, we would at that point take whatever action is appropriate. . . . It’s going to be dealt with.”

Representatives of Parsons Brinckerhoff were not available for comment Wednesday night. Earlier, the project’s chief tunnel designer, who approved the substitution of the wood wedges, declined to be interviewed.

John F. Hall, a Caltech engineering professor who has reviewed the substitution of the wedges at the request of The Times, said the assumption of wood strength was clearly faulty. “It’s really a simple undergraduate calculation,” Hall said.

White last month said he stood behind his construction staff’s decision not to seek a credit from the tunnel contractor in exchange for the use of the less-expensive wood, instead of metal struts.

Among the new report’s findings:

* The design of the tunnel bracing overestimated the stresses that the wood wedges could be expected to withstand. “Substitution of the wood wedges for the specified metal struts was inappropriate,” the report said. Transit engineers approved the substitution in 1992.

* The tunnel contractor, the joint venture of Shea-Kiewit-Kenny, failed to place dry-pack grout, as required, around the 32-inch-long wood wedges. The study cites inspection reports--drafted weeks after tunneling was halted in August--verifying “areas in both the Hollywood and Vermont tunnels where the expansion gaps were incompletely or improperly filled.”

* Despite the inappropriate substitution of the wood, the wedges probably would not have failed if they had been inserted properly and if the grouting material was placed around them in the expansion gaps, between 4-foot-wide, 8-inch-thick segments of concrete.

* Tests performed for the tunnel contractor show that the wood wedges “do not meet the submitted criteria” for strength.

Representatives of Shea-Kiewit-Kenny have declined to answer questions from the news media, citing a provision of their contract. However, the president of the company that controls the joint venture has for the first time publicly blamed transit officials for not requiring more extensive grouting of the soil to prevent ground sinkages.

Company President John F. Shea, in a letter this week to MTA board members, said that project officials “consciously” decided not to require grouting that might have stabilized the soil.

Shea also contended that the failure of the wood wedges did not cause, but resulted from, the ground sinkages of up to nine inches in Hollywood. Earlier engineering analyses concluded that the failure of the wedges contributed to the sinkages. The Wiss Janney report said that although “the crushing is believed to be responsible for much of the observed settlement,” more investigation is needed.

Shea’s letter comes as White is considering terminating the contracts of both the tunneling contractor and the transit authority’s inspection management firm, Parsons-Dillingham.

Representatives of Parsons-Dillingham have alleged that Shea-Kiewit-Kenny deliberately concealed from inspectors deficient work--the placement of improper filler material instead of required high-strength grout--around the wood wedges. Shea’s letter did not address that allegation.

White, asked Wednesday about Shea’s letter, declined to comment.

Citing the tunneling in Hollywood and earlier problems, the Clinton Administration on Oct. 5 announced a suspension of $1.6 billion in future federal funding for subway expansion. The funding will be unfrozen, federal officials said, when the MTA demonstrates that it can competently manage subway construction.

At issue in the growing disagreements over responsibility for the sinkage is who--contractors, taxpayers or both--will pay for tunnel repairs and damage claims from property owners. The total costs are not known.

Shea, in his letter, cited two types of grouting that he said were not required by transit officials:

One is compaction grouting, whereby a cement-based material is injected from street level. The material has been used to stabilize soil under which a tunnel-boring machine has passed or is about to pass.

The second procedure referred to by Shea is chemical grouting, the injection of grout through pipes from within the tunnel into soil ahead of the boring machine. It is designed to coagulate fine soils that otherwise might pour into a tunnel.

Not mentioned in Shea’s letter was contact grouting, another procedure intended to prevent ground settlement. This calls for pumping of cement-based grout from within the tunnel to eliminate air voids between the structure’s concrete segments and the surrounding earth.

The Times reported Sept. 11 that MTA officials did not enforce a contract specification requiring Shea-Kiewit-Kenny to perform contact grouting along Vermont Avenue and part of Hollywood Boulevard. Inspection reports show that even after the MTA began enforcing the specification, the contractor did not contact grout more than 340 linear feet of tunnel in the area where the ground sinkages are now apparent.

Shea said in his letter: “The decision to exclude compaction and/or chemical grouting in this critical area on Hollywood Boulevard was consciously made by the” MTA and its consultants. “These procedures are normally specified in urban tunneling to mitigate damage to property,” he said.

Transit officials have said that they, in consultation with the contractors, considered and rejected performing compaction or chemical grouting as of late July, when they found that Hollywood Boulevard had sunk by four inches.

Responding to questions posed by The Times, the chairman of the design firm of Parsons Brinckerhoff, Martin Rubin, gave this explanation last month:

“Compaction, chemical . . . and other forms of grouting were considered by the MTA, its consultants and contractors. . . . It was determined that grouting would not significantly reduce settlements.”

Rubin did not specify whether the contractors he referred to included Shea-Kiewit-Kenny and he could not be reached for elaboration. John Adams, the MTA’s interim director of rail construction, said he could not comment.