The minimum and usual mainlane width is 12 ft [3.6 m]. The number of lanes required to accommodate the anticipated traffic in the design year is determined by the level of service evaluation as discussed in the Highway Capacity Manual.
Adj. groovy is 1853 in lit. sense of of a groove; 1937 in slang sense of excellent, from jazz slang phrase in the groove (1932) performing well (without grandstanding).. As teen slang for wonderful, it dates from 1944; popularized 1960s, out of currency by 1980.
What is the meaning of 'slang'? The origin and meaning of the word 'slang' are unknown. The word  dates back the the 18th century, and may have its source in the  'argot' or thieves' language of the time.