The arch move for the Champlain Bridge has been delayed at least one day.
New York State Department of Transportation officials have opted to float the 1.8-million-pound piece of engineering on Friday, given the weather forecast.
The 402-foot-long arch was built on Velez Marine beach here.
DOT spokesman William P. Reynolds confirmed that the threat of thunderstorms Thursday made the move too risky.
"We had hoped to do it tomorrow and cautioned that weather might cause us to delay the operation," Reynolds said in an e-mail Wednesday afternoon.
"That, in fact, has occurred. Strong winds and forecasts for lightning on Thursday compelled us to postpone the operation until Friday, when conditions are expected to be much more favorable."
The move includes floating the arch to Crown Point and then lifting it, using a strand-jack system, into the opening between ramps on New York and Vermont sides of the bridge piers already in place.
Lifting the 402-foot arch into place will take four to eight hours.
The public can watch the work, but some marine and vehicle traffic restrictions will be in place.
Ferry service will remain operational during the work.
The Associated Press contributed to this story.