What do map makers use as a key to explain all the symbols used on a map

Colors are often used as symbols. ... A map usually has a legend, or key, that gives the scale of the map and explains what the various symbols represent.

Different colors and shapes are used for different symbols

Explanation:

Maps are the two-dimensional representation of the global earth. They are commonly used by the geologists and the geographers in order the study the topography and the surface features in any particular location on earth.

The mapmakers often use symbols to highlight a particular object or location. These symbols are used in the map keys. These symbols are shown on the map by using different types of colors and each symbol has a different shape.

This helps in the identification of those places. For example, the triangular symbols are used to show the mountains, roadways are shown by using dashed lines, small airplanes demarcates an airport and so on.

the underground railroad (apocope of the metropolitan railroad) is a system of urban trains located within a city and its metropolitan area. it is characterized for being a massive transport of passengers in the big cities, uniting diverse zones and their environs, with high capacity and frequency and in segregated form to other systems of transport. metropolitan railroads are built underground or on the surface, although most systems use mixed models where sections are combined in both modalities.

1 - as a result, the metro tends to reduce car travel for two reasons: first, due to the greater transfer of users from the car and, second, due to the reduction in the acquisition of cars in homes located in sectors near the stations of the metro.

2 -the metro allows to contribute effectively to the achievement of all the objectives of an urban development policy: it improves the efficiency of the city's economy by reducing travel costs and also generates a higher level of activities in the city center, taking advantage of of the agglomeration economies.

3 -it is a clean means of transport, since it uses renewable energy (usually electricity), taking care of the environment and avoiding excessive pollution.