<Li> (2) It is also describes a very narrow, urban street, or lane, usually paved, which is often used by slow - moving vehicles, though more pedestrian - friendly than a regular street . There are two versions of this kind of alley: <Ul> <Li> (a) A rear access or service road (back lane), which can also sometimes act as part a secondary vehicular network . Many Americans and Canadians think of an alley in these terms first . </Li> <Li> (b) A narrow street between the fronts of houses or businesses . This type of alley is found in the older parts of many cities, including American cities like Philadelphia and Boston (see Elfreth's Alley, Philadelphia, Pennsylvania). Many are open to traffic . </Li> </Ul> </Li> <Ul> <Li> (a) A rear access or service road (back lane), which can also sometimes act as part a secondary vehicular network . Many Americans and Canadians think of an alley in these terms first . </Li> <Li> (b) A narrow street between the fronts of houses or businesses . This type of alley is found in the older parts of many cities, including American cities like Philadelphia and Boston (see Elfreth's Alley, Philadelphia, Pennsylvania). Many are open to traffic . </Li> </Ul> <Li> (a) A rear access or service road (back lane), which can also sometimes act as part a secondary vehicular network . Many Americans and Canadians think of an alley in these terms first . </Li> <Li> (b) A narrow street between the fronts of houses or businesses . This type of alley is found in the older parts of many cities, including American cities like Philadelphia and Boston (see Elfreth's Alley, Philadelphia, Pennsylvania). Many are open to traffic . </Li>

Useful part of livable area of building is called