Needing running total formula (sort of)

[Guest_imported]

Hi, I'm new here, so thanks in advance...... I'm trying to write a report that will give a total cost for work done on a stretch of roadway by type of work and by each mile.I'll have several types of cost, but we'll just say "Labor" and "Material" (if I can do 2, I can do more). The data will come from a "work orders" table. Each WO entry has type of work, labor cost, material cost, start mile and end mile.

Now, the tricky part is for WO's that cover multiple miles (ie Start Mi = 3 and End Mi = 11 for 8 miles). For each type of work (Type A, Type B, Type C, .....) I need total cost of all WO's for EACH MILE. Total cost/Total Miles will be the cost for each mile in a WO (ie Labor Cost $80 For 8 miles = $10 for each mile.) I need to evaluate the per mile cost for each WO and then display the total cost for each mile. If another WO covers mi 1-5, miles 3, 4, and 5 need to reflect total of the two.

Did I give enough (too much?) info for someone to HELP ME PLEASE???

Thanks.....