I couldn't find any pigments for sale in Sheffield, we're lacking a really good model shop in the town centre these days, so I had to order online. Whilst waiting for those to arrive I got on with making some roads for my board.
I tinkered around with making roads out of cork, either modular or integrated into the board, but in the end went for some carved out of lino self-adhesive floor tiles. I'd found the method on this blog.
This has left me with several 1 foot sections, 6 inch sections, end pieces to allow diagonal placement and a t-junction. I have a couple more pieces that I've not shown in the photos. They're nicely weathered and sort-of post-apocalyptic. I think I need to make a curve or two to finish them off, but getting the lines right is going to be a challenge.
Someone helpfully put a guide to the sizes of US roads in 1/64th scale on the Gaslands Facebook Group, which by-the-way has to be one of the most active wargaming groups on Facebook. I also did some of my own research using the official US government guidelines, available online. The sizes I came up with are for a 2 lane highway: 6" wide total; each lane 2 1/4"; each shoulder 3/4"; lines 2mm wide, white on edge, yellow dashed line in middle: dash length: 1 1/2", gap 4 1/2". The dashed lines adjusted to make them fit on the 1 foot sections.