There are three parts to estimating,
1) Quantity Survey, how much work is there to be done?
2) How much time is allowed to get the work done?
3) Estimating Cost, how much is it going to cost to do this work in the allowed time?
I have worked as a estimator for 30 years for myself and some of the largest Contractors in the USA. Kiewit, Perini, Michels to name three, bidding excavations, roads, bridges, NYC subways and tunnels, underground utilities, etc...
I would recommend Trackware, InSite or PayDirt for earthwork and underground utilities. Trackware is very easy to use and can be leased month to month. Excel and Plan swift are helpful for areas and structural volumes.
I use HCSS "Heavy Bid" for Cost Estimating, only HCSS.
Scheduling can be done with a Excel Spreadsheet or Microsoft Project
I would also recommend HCSS "Heavy Job" for Job Cost and Project Management.
If I can be any help, send me a IM