I saw this image in the WhatIsIt subreddit, where readers were asked to provide an explanation for their intended function. I thought perhaps they were for stringing communication etc cables across the river and was delighted to read this postulated explanation, which rendered the image blogworthy:
"To plant explosives. In some countries bridges are designed to be easily blown up in case of war. Don't know if this is the case."
It wasn't long before the true explanation was provided, which I'll put "below the fold" so you can ponder for a moment...
"I’m not immediately familiar with that particular style of bridge, but when they form and pour the concrete bridge columns…. They leave through sections like this that will support the form work for the bridge deck through those slots. Once the reinforcing steel is placed and the concrete deck poured, it will support itself and then they remove the support forms and are left with the slots."
So it's a structural engineering technique; several photos have been added at the reddit post to illustrate the answer.
Pretty sure the beams and deck of that bridge were pre-formed off site.
ReplyDeleteMind you, I don't have a valid reason for the less dense rectangular portals all angled askew.
I would place red or green lights in the vacancies, in a facsimile of Christmas, to thwart any poorly driven vessels from hitting them.
Ha. Nice twist.
ReplyDeleteThis would be a good question to send to Grady over at Practical Engineering.
ReplyDeletehttps://www.youtube.com/@PracticalEngineeringChannel
A great place to hide a geocache container. I have found a couple of geocaches that use holes like these.
ReplyDeleteAnd I thought the (tiny handful) of bridges that really are intended to be blown up were built with the explosives pre-installed. It seems to be primarily a Swiss quirk. And they are tight-lipped about whether any of their infrastructure still has this stuff in place.
ReplyDeleteI can confirm that their cheese still has the demolition holes.
DeleteI saw this image when it appeared on Reddit and found it curious. I'm a civil/structural engineer who used to teach at university part time. Besides being around construction, I used to teach courses on temporary structures such as falsework and formwork. I've never seen this as a method of supporting formwork. The part that really bugs me in regard to this explanation is that the holes are not aligned with the structure. It seems to be a European type of construction. Here is an example Slovenian bridge. This is a Prestressed concrete girder bridge which wouldn't require extensive formwork or falsework.
ReplyDeletehttps://maps.app.goo.gl/GGXCM1bKBJ5Em4Ny7
https://dewesoft.com/blog/dynamic-structural-monitoring-of-highway-bridge
I think the holes are for driving precast concrete screw piles.
https://centrumpaele.dk/en/precast-concrete-piles/screwpiles/
I am recurrently amazed by the varied and advanced expertise of readers of this blog. Thank you, anon, for the comment and particularly for providing the relevant links.
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