Motor Graders in Construction
The motor grader is a large multipurpose machine used for many different construction operations. These many operations include but are not limited to: grading, shaping, bank sloping, ditching, and scarifying. Graders can also be employed to clear roads of snow and debris without doing any damage to the underlying roadway surface. Graders are much more “gentle” than dozers and other large pushing machinery. Motor graders are designed for preparing the substrate of roads and other flat earth as well as leveling aggregate. By using the blade skillfully, it is also possible for the contractor to use motor graders to finish a slope and dig a ditch. In civil engineering, the grader's purpose is to "finish grade" the "rough grading" performed by heavy equipment or engineering vehicles such as scrapers and bulldozers. Motor graders are commonly used in the construction of dirt roads, paved roads and gravel roads. The motor grader can also be used by the contractor in the maintenance of these road types and ditches as well. In the construction of paved roads they are used to prepare the base course to create a wide flat surface for the asphalt to be placed on. Graders are also used to set native soil foundation pads to finish grade prior to the construction of large buildings. The amount of material that can be pushed by a motor grader is much less than what a dozer can push. This is because motor graders are built for fine tuning surfaces rather than just pushing materials in a bulk amount. Contractors generally estimate grader production on either an area basis or linear basis completed per hour.

Motor Grader Production Calculations
The motor grader is used in a variety of application in a variety of industries. Therefore, there are many ways to measure its operating capacity, or production. One method expresses a motor grader’s production in relation to the area covered by the moldboard.
The formula for quantifying grader production in relation to area covered by the moldboard is as follows: A = S × (Le − Lo) × 5280 × E (English) A = S × (Le − Lo) × 1000 × E (Metric) Where: A = Hourly operating area (m2/h or ft2/h) S = Operating speed (km/h or mph) Le = Effective blade length (m or ft.) Lo = Width of overlap (m or ft)

Typical Operating Speeds by Application
Finish Grading: 0-4 km/h or 0-2.5 mph
Heavy Blading: 0-9 km/h or 0-6 mph
Ditch Repair: 0-5 km/h or 0-3 mph
Ripping: 0-5 km/h or 0-3 mph
Road Maintenance: 5-16 km/h or 3-9.5 mph
Haul Road Maintenance: 5-16 km/h or 3-9.5 mph
Snow Plowing: 7-21 km/h or 4-13 mph
Snow Winging: 15-28 km/h or 9-17 mph

Effective Blade Length:
Because the moldboard is typically angled when moving material, an effective blade length must be computed to account for this angle. This is the actual width of material being swept by the moldboard. The effective length becomes shorter as the angle increases.

Moldboard Length ft (m) | Effective Length at 30 Degreesft (m) | Effective Length at 45 Degreesft (m) | 12 (3.658) | 10.4 (3.17) | 8.5 (2.59) | 13 (3.962) | 11.3 (3.43) | 9.2 (2.80) | 14 (4.267) | 12.1 (3.70) | 9.9 (3.02) | 15 (4.877) | 13.9 (4.22) | 11.3 (3.45) | 16 (7.315) | 20.8 (6.33) | 17 (5.17) |
For other blade lengths and carry angles: Effective length = Cos [Radians (Blade L)] (3) (Blade Length)

Width of Overlap: The width of overlap is generally 2 ft or .6 m
Job Efficiency: Job efficiencies vary based on job conditions, operator skill, etc.
Time Required Calculations for Grader
A part of planning a construction project is estimating how long it will take to complete a construction activity. The formula to calculate the time required for a motor grader to finish an activity is as follows:
Number of passes × Length of pass(mi) Average speed×1Efficiency=Time(hr)

Motor Grader Calculation Examples

Example Calculation 1:
A motor grader with a 12 foot mold board is performing road maintenance on a township road. The machine is working at an average speed of 8 mph with a moldboard carry angle of 30 degrees. Due to the long passes involved in road maintenance, a higher job efficiency of .90 is chosen. What is the motor grader’s production based on coverage area?
Solution:
From the table, the effective blade length is 10.4 feet Production = (8mph) (10.4ft – 2.0ft) (5280) (.90) = 319,334 ft2/hr

Example Calculation 2: Five miles of grave road is to be leveled and reshaped by using a grader with a 12-foot blade. Six passes are estimate to complete the leveling and reshaping operation. The type of material permits passes 1 and 2 to be performed in second gear at 2.8 mph, passes 3 and 4 in third gear at 3.4 mph, and passes 5 and 6 in fourth gear at 5.4 mph. The efficiency factor for the job is 60 percent. How long will it take to complete this job?

Solution:
Total time for passes 1 and 2 = 2 × 5 2.8×1.6=101.68=5.90 hours

Total time for passes 3 and 4 = 2 × 5 3.4×1.6=102.04=4.90 hours

Total time for passes 5 and 6 = 2 × 5 5.4×1.6=103.24=3.08 hours

Total time of the project = 5.9 + 4.9 + 3.08 = 13.88 hours Always round up to the next higher full number: 13.88 rounds up to 14 hours