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 Cost of Electrification is about 1.4Crs/Km for double line section as compared to construction of new line which is about 10 Crs/Km and return from new line is always had been very poor.2  In fact it is now only, the realization has set in that if Railway has to survive, it has to go for sustainable traction. Cost of Electrification is about 1.4Crs/Km for double line section as compared to construction of new line which is about 10 Crs/Km and return from new line is always had been very poor.