Route Survey Of The Stretch Of Road From Oriawo Along Ogbomoso Road, Oyo To School Of Science, Sabo Oyo Town, Atiba Local Government Area, Oyo State

After deduction of the level observation, the height of each station was computed by using Rise and fall method. The following formulae were used in Rise and fall method:
B/S- I/S   = ± (Rise or fall)
B/S- F/S   = ± (Rise or fall)
I/S - F/S   = + (Rise or fall)
I/S –I/S    = + (Rise or fall)
If (+) that means it is Rise
If (-) that means it is fall
Definition of the terms
B/S = Back Sight Reading
R/L = Reduce Level
I/S = Intermediate Sight
F/S=Fore Sight
+    = Rise
-     = Fall
4.2.3.1 LEVELING ADJUSTMENT
These values (Rise or fall) plus reduce level of the starting benchmark gives the new uncorrected reduce Level. The provisional reduced level (calculated observed level) of the closing station was compared with the existing height of the same station known as the closing benchmark. This was done by subtracting the existing height of closing benchmark of a station from the provisional calculated height or reduced level of the same station. The differences between the two are the height difference. The height difference can be addition or subtraction (±). If it is negative (-), the correction would be positive (+) and if it is negative (-), the correction would be positive (+) and it was shared by using this formula

The adjustment was done to get the final level for each station
4.2.4 ACCURACY
4.2.4.1 ANGULAR ACCURACY
         The formula used for obtaining the allowable angular misclosure was 30” √n
Where n = Total number of stations occupied
Allowable angular misclosure =30”√22 = 00°02’20.71”
Obtained angular misclosure=00° 02’ 6.6”
4.2.4.2LEVELING ACCURACY
    The formula used for the accuracy of the leveling was 24mm√k where k is the total distance in kilometer. This is the allowable Misclosure of third order engineering leveling. A quick check is usually done on the field by summing all the back sights and all the fore sights so as for the sum should be equal to each other. And the difference between them should not exceed the decimal.
The leveling accuracy of the operation is determined by the expression 24mm √ k
Where k is the total distance in kilometer
= 24mm√2.725km
                        =24 * 1.679285562
                        = 40.3028535mm
Allowable height difference =0.040m
Observed height difference = 0.040m