Tender process should handle by special departments, in my company it is procurement and constracts. But for the process they will involve small team (tender committeee) to negosiate and decide which best vendor they choose for do the works (tender winner).
Here is the stage :
1. Request for quotations from contractors. If they want to participate, contractorss must do site visit.
2. Internal meeting to see how to process the tender
3. Technical Clarification to ask contractors how they calculate, if find mistake ask them to revise
4. final negosiation and awarding contract to the right candidate. Score based on the cost, experience, finance capacity, technical ability etc.