Thread by @rossatkin

I designed a new street thing last year, and I’ve seen a few of them out in the wild now so I figured it was time tell you all about it! It’s a support for temporary road signs. It’s made from recycled plastic and replaces a steel A-frame and sandbag. 🧵1/

The steel A-frames are pretty awful things and IMO they should never have started appearing on our footways because:

1. Long cane users can easily get their canes trapped (and possibly broken) between the legs 2/

2. The sandbags can fall off, presenting a trip hazard and meaning the sign falls over (another trip hazard + missing sign)

3. The weight of the sandbags depends on how much sand was put in so there might not be enough weight to resist the wind loading causing more falls (2) 3/

4. If the A-frames end up left on the street with no sign face on they are difficult to see and can do serious damage to any cyclists or motorcyclists that hit them. I’m aware of at least one fatality. 4/

They are scaled-down versions of the huge A-frames used on Motorways. It seems they’ve appeared on streets for two main reasons:

1. Safety auditors are asking for signs to be positioned higher up (so they are not obscured by taller SUV-type cars). 5/

2. Requirements for more and different kinds of signs mean that the companies setting lots of them up prefer to use signs where different sign-faces can be fitted to a single support. 6/

The new support I’ve designed with the good people at P.F. Cusack is compatible with all the sign faces that go on the A-frames, but it switches out both the steel frame and sandbag for two lightweight blow-moulded HDPE pieces and a heavy injection-moulded PVC base. 7/

These are the two materials with go into barriers and cones. Unlike consumer products where you make thousands of a thing and sell one or two each to thousands of different people, Cusack sell thousands of things each to a handful of customers. 8/

This means at end of life it’s very easy for them to get their old barriers and cones back. They’ve built a recycling centre where they separate the materials and grind them up ready to be made into new products. 9/

I did a Life Cycle Assessment. Making our new support this way creates the equivalents of 3.7kg of CO2 emissions. The A-frames it replaces contain 12kg of steel; making this alone creates the equivalent of 21.2 kg of CO2 emissions. So 83% reduction in manufacturing emissions. 10/

Our new support (called The Highway Sign) is also 49% lighter than the steel A-frame and (correctly filled) sandbag, which leads to a reduction in CO2 emissions of just over 1g for every mile it is moved. 11/

Reduced weight means more of them can be carried on a vehicle, halving the number of vehicle movements (and the associated externalities) to set up a large job.

As you’d expect I’ve also tried to design something that is as little of an imposition on the footway as I could 12/

It takes up less of the footway than the A-frames and I tried to shape the base so that it would be easily detectable by long cane users, without being likely to trip anyone else. The ends are painted yellow to maximise contrast with the paving surface and rest of the sign. 13/

I’m still not delighted that these things can be put on the footway at all, or that some of the sign faces that can be attached overhang the base by more than the 150mm allowed by ‘Inclusive Mobility’ (p34)
14/assets.publishing.service.gov.uk/media/61d32bb7…

Both of these things are currently allowed by the document that controls how road works are set up ‘Safety at Street Works and Road Works; A Code of Practice’.
15/assets.publishing.service.gov.uk/media/5a7d8038…

Spotted some of them loking nice in the sunshine near my studio just now.

This is another failure mode for the A-frames + sandbags I forgot to mention. This sounds like a very scary situation.

https://twitter.com/muckyfellrunner/status/1796177918751658203

Spotted in Solihull!

https://twitter.com/ianmspencer/status/1796204579769475210

And Crowborough!

https://twitter.com/chrisgrose2/status/1796207440410636731

Another horrible interaction with one of the A-frames

https://twitter.com/boxrick/status/1796316770631848177