I take a lot of public transport and I sometimes try to imagine what might make pedestrian routes nicer/safer.
I've noticed a lot of places with poorly designated pedestrian routes, particularly alongside A roads and the like, those awkward areas where countryside has been sliced by traffic. My most recent idea was, rather than railings, what if these routes had a simple separator made from biodegradable plastic? I'm trying to imagine materials which might absorb CO2 emissions from vehicles as they drive by, also. Carbon dioxide scrubbers? Perhaps they could be intergrated?
Also, if the aesthetic doesn't appeal, perhaps they could be trellis-like, with plants grown throughout.
I just thought a simple dividing border like this could be useful as an indicator, ecologically sound, and hopefully quite cheap. Someone please feel free to tell me my idea is stupid.
The "railings" in the middle of a dual-carriageway are specially designed safety barriers that do a very complex job. They are there to prevent vehicles from crossing over into the other carriageway (to prevent head-on crashes). They need to be flexible enough to cushion the impact, but not so flexible that they catapult cars out into the inside lane. They also have to deal with a huge range of vehicle weights, from a 700kg smart car to a 44 tonne lorry. The design of these barriers is a constant work in progress and they are a crucial safety technology.
The better solution for pedestrians is segregation - providing alternative paths that are protected from traffic and noise. Walking alongside a busy arterial road is never going to be pleasant, but it's usually quite easy to design pedestrian routes that are separated from that traffic. Where you have pedestrians interfacing with dual carriageways you have a fairly costly engineering challenge to provide crossings (bridges and underpasses don't come cheap) so you generally want to keep pedestrians away from such routes.
I didn't mean so much the barriers in the center, but rather guard rails like the ones pictured (which are usually only placed along specific stretches of road).
Those barriers exist mainly to route pedestrians towards safe crossing points. Their design is less complex than a median barrier, but they're still built to provide the greatest possible energy absorption in the event of a vehicle impact, protecting both motorists and pedestrians. The design of these barriers is prescribed in British Standard 3049 - much more thought has gone into their design than you might imagine.
The use of pedestrian barriers at all is a hotly disputed topic amongst planners and traffic engineers. In many circumstances, the use of barriers reduces the visibility of pedestrians to motorists, which can dramatically increase the risk of accidents. Guardrails can be almost completely opaque at some angles, which poses an especially serious risk to children. Any design that worsens the visibility problem is a complete non-starter, as most new guardrail designs are specifically optimised to improve visibility.
There might be a case for transparent polycarbonate barriers, but these would have several downsides - less energy absorption in the event of a crash, higher cost, lower durability and greater vulnerability to vandalism.
Thanks for this. I'm not a motorist nor an engineer, so perhaps I shouldn't venture like this, but I do think that perhaps there's an argument to be made for visibility over the aptitude of the materials, particularly in places where there's no barrier at all.
It occurs to me now that my 'trellis' idea would be bollocks, unless the plants were very low to the ground.
I also wanted to mention that I recognise the practical solution you offered in your last post, but I encountered one of those areas where segregation isn't possible today. It doesn't sound like much, but alongside certain roads even the smallest indication that pedestrians have an area where they are meant to be makes the entire experience much less alien. I remember having to cross a dual carriageway, and even a hint of tarmacked path showing the accepted route was a great comfort.
About damage and vandalism, I'd hope that the materials would be cheap enough so that the individual panel could be replaced in the event that one gets destroyed by vehicle or drawn on. I also had this idea that the barrier would be high and arched with kind of curved roofing lip at the top, but this would probably be too costly and may attract enough glare to distract drivers.
