The opening of Amsterdam’s new Noord/Zuid metro line may be further delayed, the Parool has reported.

Independent experts are extremely critical of keeping to the latest date for opening on July 22 and Pieter Litjens, the alderman responsible public transport, now says he will make a decision this month, but after the local elections.

Although the original budget for the north/south line was €1.4bn, the final cost is likely to be well over €3bn. Work started in 2002, and was due to end in 2011 but ran into massive buildings subsidence problems and technical issues along the way.

The experts’ report urging a further delay has been around for a month, but was only published officially earlier this week. It says there has been insufficient time to train personnel which only increases the chances for the failure of a new security system.

The report also mentions that there are glitches in the test runs on the system with traffic control screens often going blank for several minutes.

Bottlenecks have been discovered which mean that only 10 trains an hour at most can run through the system instead of 12. In 2009, engineers were expecting to move 16 trains per hour through the system.