20 seconds about your bridges and Japan

Tasmania has 1,300 bridges, South Australia has 1,500, Brisbane alone has 20. You do the maths for all of Australia and New Zealand.
The issue is that many bridges over time deal with erosion of river beds, while fast flowing floods can do real damage. Most vulnerable are the pylons, where water flows increase in speed when they have to go around them. How can we deal with this erosion and bridge stability? We place large rocks, pebbles,
maybe concrete too.
Now let’s look overseas: 30 years ago the Japanese built an almost 4 km long Akashi Bridge and placed Rock Filter Bags around the pylons as scour protection.
These rock bags weigh 2, 4 or even 8 tons and have since been used in 17,000 (!) projects.
The best solutions are often the simplest. After 30 years they are now finally available in Australia and New Zealand, where Councils and construction companies have already adopted them for road, river bank and beach erosion projects. Not quite as sexy as the transistor radio, but still a very useful product from Japan.