Many countries have laws that require tactile indicators be included in new construction. But what do all those bumps and lines in the sidewalk indicate? I will try to give a brief overview, keep in mind, the rules may vary by country.
Flattop dome patterns are arranged in rows that comprise a square shape. It is used to indicate where the sidewalk ends and the road crossing begins. A flattop pattern is used so that not to hinder those who are crossing in a wheelchair.
On street rapid transit or railway
Here rounded bumps in the shape of a lozenge are placed to indicate that you are approaching an on-street rail platform. I have also seen this pattern used to indicate that you are leaving an area in front of a store and proceeding into a parking area.
Here rounded bars are placed perpendicular to your walking root to indicate caution ahead. These types of tactile patterns are used to indicate stairs ahead, a ramp ahead, a rail crossing, or any hazard that public designers believe a blind or visually impaired person needs to be aware of.
Here the same rounded bars are arranged as in the hazard warning patterns, but here they are arranged in a pattern that is parallel to the direction you are walking. You can walk on the surface of the pattern, or use a cane to help guide you in the correct direction. These tactile patterns are also used to mark the separation of pedestrian walk ways and bike lanes.
The use of color varies wildly mainly due to esthetic concerns; however, the general rule is that the color of the tactile patterns be a contrasting color to the surrounding surfaces. This allows for low vision travelers to see the patterns.
This is a very simple summary of tactile patterns found on sidewalks, and the rules vary from country to country, and even from town to town, sense many city planners have difficulty deciding which patterns are best to use in different areas.