A study carried out in 2009 by University College London recommended that a kerb of 60mm or greater would be needed in order to be detected when stepping up and stepping down and induced the greatest confidence in what they were and what they signified.(Effective Kerb Heights for Blind and Partially Sighted People)
Tactile signage could help to indicate safest places to cross, for example, at a courtesy crossing.
The differentiation of areas by colour on shared surface streets is seen as useful for those who are partially sighted.
Instead of a kerb, a textured area may be introduced, between the shared space and the safe space. If a guide dog went into this area, the person steering the dog might recognise the change in surface and decide to steer themselves back to the safe zone.(RambØll Nyvig Report pdf)
BBC Discussion indicates tactile safe surface is a success.