The new Nowolazurowa street previous unofficial name, later changed to 4th of June 1989 Avenue) is covered with noise barriers beyond the limit of absurd (another cache is connected with this subject). But there is also another interesting fact about this street. It is the tunnel under the railway line Warszawa - Poznań, next to the station of Warszawa - Ursus Północny. What is so unusual about it ? The first fact is that is not perpendicular to the railway line, but skew. But the most interesting was the technology of its construction. The railway line is very busy, local trains to Błonie, Sochaczew and Łowicz pass it, as well as the express trains to Poznań or Berlin. So closing it for a long time could cause much problems for passengers. To minimise those difficulties an unusual operation was made. The concrete structure of the tunnel was initially constructed not in the target place, but a few metres away. Then, after closing the railway line, some fragment of it was disassembled, together with the banks. Then, the concrete base was constructed, and - what was the most interesting - the already prepared tunnel was transported to its place. Later the banks and the railway track were restored. Thanks to such method, the whole operation took just a bit more than one week (starting from the long weekend of 15th of August 2012 and few days after it). How it is possible that it was done so quickly ? Some explanation can be the fact that it was a part of a bigger road investment. Probably it was necessary to pay some compensations to the rail companies for closing the tracks and directing the trains to bypasses. So there was a pressure to finish it as quick as possible. Probably, if the investment had been done by the railway company itself, such hurry would not take place, everything would have been done with the full relaxand passengers would probably have to ride through bypasses for a few months :)

Some photos and films from this unusual operation can be seen here:

http://www.skyscrapercity.com/showthread.php?t=528872&page=60

And the article (in Polish) about it is here:

http://tvnwarszawa.tvn24.pl/informacje,news,10-500-ton-wsuneli-pod-nasyp-16-godzinna-akcja-w-przyspieszeniu,55238.html

As one internet user noticed, the moving of the tunnel itself actually did not require huge powerOne man with a crowbar was enough(you can see it on the film above about 01:55).

Attention ! The cache is located in a fully accessible place, it is not dangerous to get it, you can reach it directly from the pedestrian route. You should not even try to climb the railway escarpment and especially you should not cross the railway track - it is extremely dangerous and can result in death, because the traffic on this line is very intensive. You also should not cross or even approach the carriageway of 4th of June 1989 Avenue. The author of the cache and the owners of the service does not hold the responsibility for any potential actions of persons who would ignore this warnings and would try to step into the railway area.