They span a straight line from their points that emerge out of the desert, each over a thousand kilometres long. Supporting the bridges at regular intervals are columns with wide spiralling ramps burying into the sand that that enable travellers to enter and exit the Glassroads at various points, with small settlements often cropping up at the top of these columns and at their base.
Aside from facilitating travel across the Sandsea, the Glassroads also act to collect rainwater that falls on their surface as well as atmospheric moisture evaporated off the desert surface and carried by weather. The pale colour of the roads and insulative properties of glass - as well as being raised off of the desert floor - prevent water collected in channels along either side of the highways from evaporating. Very shallow inclines along the roads direct water to the struts supporting them, enabling small oases to spring up around them.
The roads also inevitably collect sand along their surface, both carried by the wind and strewn about by sandstorms. The slightly-raised centre along the roads directs the sand to the same channels where water travels through. Normally the two materials would mix and be difficult to separate, making the strut-oasis communities impossible, but subtle vibrations - believed to be a small contribution of the Kinemancers - cause the water and sand to separate The vibrations also move sand towards the struts, much like the Euronian mine-roads method of ferrying materials, however it does not appear to be re-introduced into the desert ecosystem like the water. Instead, it is believed to be stored and compacted underground, over time 'draining' the Sandsea to open up more habitable space across Aschaea, but at such a rate that ecosystems and weather can adapt to the changes. The vibrations in the road, though not susceptible through booted feet, are just audibly perceptible, and the phenomena is popularly romanticised as 'travelling song' for those moving along the roads.