Nighttime lane closings on the Bay Bridge will extend into the fall of 2009 - about six months later than planned - because of changes in the Maryland Transportation Authority's plan for replacing the deck of the westbound span.
Geoffrey Kolberg, the toll facility authority's chief engineer, said yesterday that plans for redecking the bridge were changed after consultations with contractors American Bridge and URS.
Instead of using a two-step process for replacing slabs of pavement, the authority will adopt a less ambitious but more expensive three-step process that doesn't demand as precise measurements on the first try.
"It's a better way of doing it," said authority spokeswoman Cheryl Sparks.
The previous plan had called for a $60 million second phase of the redecking to be finished in the spring of 2009. Now the state is aiming for fall of that year, Kolberg said.
Sparks said it was unclear whether work would be suspended during the summer of 2009, but she said any work that's done during that season would be completed outside of peak travel times.
The authority had previously said there would be no major summertime lane closings this year or next.
The changes to the plan affect the redecking of the "through-truss" segment of the bridge. That section lies east of the suspension part of the bridge - the highest part - and closer to Kent Island. The suspension bridge redecking will not be affected by the revised plans, Kolberg said.
Previously, the authority had planned to pull out the old concrete slabs and replace them with prefabricated permanent replacement sections on the same night.
The new plan calls for the old slab to be replaced with a temporary deck section over one night and for the temporary section to be replaced by the permanent section on a single night later in the project.
Kolberg said the revised plan gives the contractors more time to do precise measurements for the permanent replacement sections.
The second phase of the project will begin in September and continue for two years. As previously planned, it will involve closing the westbound span between 8 p.m. and 5 a.m. on some weekday nights. Traffic on those nights will travel in both directions on the two-lane eastbound span.
"As far as the driving public, they won't see any difference," Kolberg said.
The first phase of the $120 million redecking project, which began in 2001, ran into trouble in 2004 when some of the concrete failed to set properly and had to be scraped up and replaced. In that case, drivers did see a difference as the authority closed all but one lane of the westbound span at rush hour to speed the repairs. The closings led to huge backups and a public outcry.
For the second phase, the authority decided to scuttle the system of pouring concrete in place and instead replace the deck in huge prefabricated sections - each 20 feet wide and 15 to 49 feet long. The method is expected to avoid some of the weather problems that prevented the poured concrete from bonding properly during the first phase.
Kolberg said the most recent revision to the plan would involve additional cost, but he added that the authority and its contractors have yet to determine how much.
michael.dresser@baltsun.com