Steps in Bituminous Road Construction Estimating Its Unit Costs
Asphalt bituminous road construction involves multiple steps and stages while estimating its costs vary considerably depending on type and size of the job, access, terrain, and job location.
types of bituminous road
Various such steps are discussed, including the preparation of the base layer, the application of the bituminous coating, the placement of the bituminous mixture, rolling and quality checking.
Road construction supervisors can often estimate how many meters per hour their equipment can build roads by looking at the terrain based on local experience.
The engineer's approach is to use a formula or table to calculate the cubic meters to be excavated to calculate the amount of earthwork as a function of side slope, road width, and cut-to-fill slope ratio. Product prices apply to bulldozers and hydraulic excavators.
Asphalt pavement construction stage
Preparation at the level of existing foundation courses
Prepare the surface by removing existing pits or rust. At least one week before paving, fill irregularities with premixed chips.
If the existing pavement is a pathway, provide an asphalt screed of sufficient thickness to lay the asphalt concrete surface, rather than laying the asphalt concrete surface directly on the WBM.
Application of Talking Coat
Ideally, the AC layer is applied over an asphalt base or adhesive layer. Apply 6.0 to 7.5 kg of bituminous bond per 10 m² area, this amount can be increased to 7.5 to 10 kg for non-asphalt bases.
Premix preparation and storage
Premixes are prepared in a hot mixing plant of the required capacity and subject to the necessary quality controls.
Asphalt can be heated to 150 - 177°C, the difference between the total temperature and the binder temperature should not exceed 14°C. The hot mix is spread by mechanical pavers at temperatures between 121 and 163°C, then collected from the mix by conveyors and transported to the site.
Arc and layer thickness are accurately verified. Temperature control during mixing and compaction is very important to the strength of the resulting pavement structure.
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Once placed on the base layer, the mixture is thoroughly compacted by rotating at more than 5 km/h. Initial or disintegrating rolling with 8-to-12-ton rollers and intermediate rolling with 15-to-30-ton fixed wheel pneumatic rollers with a tire pressure of 7 kg/cm². Keep the rollers moist with water.
The number of passes required depends on the thickness of the layer. Rolling on the second day in hot weather can help increase density if the initial rolling is insufficient. Final rolling or finishing is done by tandem rolls of 8 to 10 tons.
Asphalt Concrete Construction Quality Control
Periodic site inspections are carried out to ensure the quality of the resulting pavement mix and pavement surface.
Periodically check a) aggregate grading b) asphalt grade c) aggregate temperature d) temperature of paving mix during mixing and compaction. For every 100 tons of mix discharged from a hot mix plant, at least one sample is collected and tested as required above. Military tests were also carried out.
For every 100 square meters of compacted surface, conduct an areal density test to check for the presence of at least 95% of the laboratory-obtained density. The allowable thickness variation is 6mm per 4.5m length of structure.
Finished surface
Road Construction - AC surface finish should be checked with a 3.0 m ruler. The longitudinal undulation shall not exceed 8.0 mm, and the number of undulations exceeding 6.0 mm shall not exceed 10 within a length of 300 meters.
The cross-traffic profile should not have undulations greater than 4.0mm. Read more: Why is asphalt used in road construction? Properties and Benefits of Asphalt for Pavement
bituminous road construction
The road construction unit costs in dollars per kilometer is the sum of the sub-unit costs of road construction activities.
Estimating these unit costs can be done by dividing the machine rates of the production rates for various activities involved in road construction. The road construction activities considered here are surveying, clearing and excavation, excavation, surfacing and drainage.
Surveying
Survey and stakeout costs vary by job type and size, access, topography and job location. One way to estimate production is to estimate the number of piles that can be set per hour and the number of piles that must be set per kilometer.
For example, with a preliminary survey line already in place, a crew of two people can set about 15 stakes per hour. A typical five-point segment consists of two reference teeth, two helical teeth, and one end centerline tooth.
Clearing and Piling
Clearing and piling costs can be calculated by estimating the number of hectares that need to be cleared and piled per kilometer of road. The clearance productivity is the number of hectares that can be cleared per hour, in km/h. Cleanup can be done in a number of ways, including by someone using an ax or chainsaw.
Saleable logs can be removed by skidders or tractors, and the rest can be tractor-incinerated or piled to rot. The fall rate and slip rate of logging can be used to determine the cost of removing saleable logs.
In soft terrain, if the wide right of way is cleared after frequent rains to allow the sun to dry the pavement, the project can be considered a land clearing project.
Here's how to estimate the total time per hectare required for clearing, digging and piling in loose terrain using tractor and mower blades. More Details Caterpillar Performance Manual No. 21 can be found at Caterpillar, Inc.
Mechanized Clearing
Clearing time will depend on the size of the tractor and the number and size of trees. The cleaning time Tc in machine hours per hectare is Tc = (X/60) (AB + M1N1 + M2N2 + M3N3 + M4N4 + DF)
where X is the hardwood density factor, A is the vine density factor, B is the base per hectare, M is the number of trees per hectare per diameter range, and N is the number of trees per hectare per diameter range.
is the sum of the diameters per hectare of all trees larger than 180 cm in diameter, and F is the number of minutes per cm diameter felled for trees larger than 180 cm in diameter.
Example:
Five hectares per kilometer of hardwood right-of-way is being cleared for the road. Of the five hectares, 1.2 hectares of stumps need to be removed per kilometer. Tractor rates are $80 per hour.
bituminous road in hindi
Earthwork
The earthwork cost is calculated by estimating the number of cubic meters of common material and rock which must be moved to construct the road. The earthwork production rate is calculated as the cubic meters per hour which can be excavated and placed divided by the number of cubic meters per km to be excavated.
For example, a 6.0-meter subgrade on a 30 percent slope with a 1.5:1 fill slope and 0.5:1 cut slope with a one-foot ditch and a 20 percent shrinkage factor would be approximately 2100 bank cubic meters per km for a balanced section.
An average production rate in common material from an equipment performance handbook might be 150 bank cubic meters per hour for a 300 hp power-shift tractor with ripper. The tractor cost is $80/hr.
If the earthwork is not being placed or side cast within 50 meters of the cut, the production rate for pushing the material to the placement location must be made. Scrapers or excavators and dump trucks may be used.
Excavation rates in rock vary with the size of job, hardness of rock and other local conditions. Often there is a local market price for blasting.
Estimates of blasting production can be made by knowing the size of equipment and the type of job. For example, a 10 cm track-mounted drill and 25 cubic meter per minute air-compressor may prepare 40 cubic meters per hour for small, shallow blasts and 140 cubic meters per hour for larger, deeper blasts including quarry development to produce rock surfacing.
A major cost will be explosives. For example, 0.8 kg of explosive such as Tovex might be used per cubic meter of rock at a cost of approximately $2 per kg.
Finish Grading
Finish grading of the subgrade can be estimated by determining the number of passes a grader must make for a certain width subgrade and the speed of the grader.
This number can be converted to the number of hours per hectare of subgrade. For example, a 120 hp grader may require about 10 hours of productive machine time without delays per hectare of subgrade or 0.1 hectares per hour.
Surfacing
Surfacing costs are a function of the type of surfacing material, the quantity of surfacing material per square meter, and the length of haul. Local information is the best guide in constructing surfacing costs due to the wide range of conditions that can be encountered.
Natural gravel from streams may require only loading with front-end loaders directly to dump trucks, transporting, spreading, and may or may not be compacted.
Laterite may be ripped by crawler tractor, loaded by front-end loader, transported, spread and grid-rolled with a sheep's-foot roller to produce a sealed running surface.
Rock may have to be blasted, loaded into one or more crusher(s), stockpiled, reloaded, transported, spread, and compacted.
bituminous road layers
The costs for each of these operations can be developed by estimating the equipment production rates and machine rates.
Equipment balancing plays an important role in obtaining the minimum cost per cubic meter for surfacing. In some areas, market prices for various types of surfacing may exist and tradeoffs between aggregate cost, aggregate quality, and hauling distance will have to be evaluated.
Since surfacing is often expensive, a surveying crew is sometimes added to stake and monitor the surfacing operation.
Drainage
Drainage costs vary widely with the type of drainage being installed. The costs of drainage dips, culverts, and bridges are often expressed as a cost per lineal foot which can then be easily applied in road estimating.
Local values for cost per lineal foot for culverts and different types of bridges are generally available. If not, constructed costs can be made by using time study data.
Factors Affecting the Cost to Build a Road
The cost to build a road will primarily depend on what material you use and its size. Of course, the longer the road, the more expensive the final cost. Ensure you choose the correct material for your climate.
If your area is prone to heavy rainfall, you should opt for permeable concrete or tarmac that will ensure water runoff is not an issue.
However, depending on the subsoil type, surface water drainage may still be required. Types of road construction materials: Permeable concrete is a hard-wearing, low-maintenance option but is prone to cracking if installed poorly.
Expect to pay from £35 per sq m. Permeable tarmac is durable, low cost, and a high-quality sealant will make it last longer. Expect to pay around £20 per sq m. Gravel is pocket-friendly and quick to lay. It also offers a range of color options. Gravel road construction costs range from £60 per sq m.
What About Shared Access Road Maintenance?
A private road with shared access is the responsibility of all the road users. The title deeds of a property should clearly state the access details and any existing arrangements or costs of maintenance.
Setting up a residents committee to organize maintenance and costs might be a good idea to encourage smooth communication between all parties. What private road maintenance costs do I need to factor in? A private road is the responsibility of whoever owns the land, not the local authority, and like all roads, they need maintenance after years of use, or they could cause damage to vehicles and result in poor drainage.
Regular ongoing maintenance, like road sweeping, should also be taken into consideration. Road sweeping & gulley cleaning will be a minimum charge per half day or full day charge.
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