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.
A discount rate of 7.95% was used to estimate the total benefits, in 2002 dollars. The net benefits were evaluated to be $2,067,263,000. The estimated costs for constructing and operating the monorail are $1.68 billion (in 2002 dollars). This includes a total capital cost of $1.26 billion and a total discounted stream of operating costs of $420 million (at approximately $29 million a year), using the same discount rate (7.95%).