The good news is that now every pole is now a breakaway unit, even if it was not when installed. Here the old poles took a century or more to rust through, even if they were never painted, whilst the newer units might make 15 years before failure. The concrete poles last around 10 years, whilst the GRP poles have mostly been replaced as they were cut down by cable thieves.
Concrete poles do not like chloride corrosion, especially on the seafront promenade. Further inland they will easily do a century. the galvanised steel poles have a pretty good life, provided they do not become roadkill. The only poles that survive roadkill are those with cameras or highbay units, they are big with a massive concrete lower support. Even 65 ton truck merely dents the lower support braces a little and scratches the paint.
Rust resistant until more than 30% or so of the galvanising is gone, then they go bad very quick. Painting every few years helps, but new poles need around 6 months to weather before painting, otherwise it peels off.
@Sean 10 Years isnt a long service life i guess.