The atoms that make up a molecule can be of the same element or different types. Diatomic molecules are a specific class of molecules that consist of two molecules of the same element. If the molecule is composed of atoms of at least two different elements, it is a chemical compound.
The cost of light rail construction varies widely, largely depending on the amount of tunneling and elevated structures required. A survey of North American light rail projects shows that costs of most LRT systems range from $15 million to over $100 million per mile.he cost of 17 miles (27 km) of highway improvements and 19 miles (31 km) of double-track light rail worked out to $19.3 million per highway lane-mile and $27.6 million per LRT track-mile. The project came in under budget and 22 months ahead of schedule.
1 Value added of the U.S. rail transportation industry from 2000 to 2016 (in billion U.S. dollars)Rail transportation: U.S. value added 2016. 2  Expenditure on U.S. freight railroad's infrastructure and rail equipment from 2006 to 2016* (in billion U.S. dollars)U.S. freight railroads: infrastructure & equipment costs 2006-2016.