US transportation agency New Jersey Transit has temporarily halted work on the planned $8.7bn Trans-Hudson Express tunnel project to New York over concerns it may run $1bn over budget.
The state also suspended contract awards for a month to determine whether the project's cost will be covered in the budget.
Ongoing work, including a track underpass in North Bergen and a tunnel segment under the Palisades, will commence during the suspension.
The tunnel project is scheduled to be completed by 2018 and will double the number of trains running between New York and New Jersey.
The US Government and the Port Authority of New York and New Jersey have each contributed $3bn to the project.
More than $600m has been spent on the project and $1.2bn has been committed in contracts, according to nj.com.