CONSTRUCTION EQUIPMENT MANAGEMENT NOTES 06

NOTES - 06

EQUIPMENT MANAGEMENT TIPS FOR THE CONSTRUCTION ENGINEERS 

AND PLANT & MACHINERY ENGINEERS

AN INTRODUCTION TO CONSTRUCTION PLANT AND EQUIPMENT

HOW TO PLAN AND SELECT EQUIPMENT FOR A CONSTRUCTION PROJECT

HOW TO SELECT THE EQUIPMENT

ESTIMATION THE EQUIPMENT PERFORMANCE NORMS

 Selection of Equipment needs careful thought to ensure efficient and effective performance. Though the actual selection would depend on factors like type of the work, its magnitude location etc. certain guidelines can be laid down. Basically the various operations involved are as below:

a. Earth moving

i. Clearing and grubbing

ii. Stripping

iii. Earth work in cutting and embankment

iv. Spreading earth for bank work

v. Providing camber

vi. Watering

The following Table shows the suitable equipment for the works mentioned above.

EARTH MOVING OPERATION

Table-1

Selection of Equipment

No.		Operation		Suitable Plant	Remarks
i.	a.	Clearing & Grubbing	a.	Tractor mounted dozer	Blade to be used in bulldozing position
		Light/scrub & grass	b.	Grader motor	For light scrub
		Clearing debris rubble	a.	Tractor mounted dozer
			b.	Tractor with heavy duty winch	For large objects
ii.		Stripping Top soil	a.	Dozer, tractor mounted
			b.	Motorised- Scraper	300 m. to 3000 m. haul
				Tractor towed Scraper	60 m. to 3000 m. haul
				Grader, motor	light stripping
			c.
iii.		Earthwork in cutting and embankment	a.	Dozer, tractor mounted
		Light & medium soils	b.	tractor towed scraper	for hauls 60 m. to 300 m.
	a.		c.	motorised scrapers	hauls 300 m. to 3000 m.
			d.	Grader motor
			e.	Excavator and dump trucks
			f.	Front end loader
			g.	Tipping bucket
	b.	Heavy soil	a.	Dozer Tractor mounted	Upto 90 m. haul
			b.	Scraper ractor towed with pusher tractor to help loading or preceded by tractor towed rooter or tractor mounted ripper
				Motorised scraper with pusher tractor or preceded by tractor towed rooter	haul 60 m. to 300 m.
				Grader motor preceded by tractor towed rooter.
			c.
					haul 300 m. to 3000 m.
			d.
iv.		Spreading earth for bank work	a.	Scraper tractor towed	60 m. to 300 m.
			b. c.	Scraper motorised	300 m. to
			d.	Grader motor	3000 m.
			e.	Tipping trucks
				Dozer, tractor mounted
v.		Providing camber	a.	Grader motor
			b.	Dozer, tractor mounted
			c.	Scraper tractor towed motorised
vi.		Watering (Embankment or surfacing)		Truck or trailer mounted water tanker with water pump and sprinkler

Table – 2

No.	Work		Plant	Remarks
i.	Compaction of bankwork and subgrade soils	a.	Sheepsfoot roller
		b.	Smooth wheel and roller
		c.	Pneumatic tyred roller
		d.	Vibratory roller
		e.	Power rammer
ii.	Granular base and sub base	a.	Smooth wheeled roller
		b.	Vibratory roller
iii.	Macadam base/ sub base	a.	Smooth wheeled roller
iv.	Mix-in-situ bituminous base	a.	Steel wheeled roller
			Vibratory compactor
v.	Plant mix base course or surface course	a.	Three wheel roller
		b.	Tandem roller

  

Table - 3

Plant and Equipment Concrete

No.	Operation	Pavement Plant
i.	Manufacturing Concrete	Concrete mixers
ii.	Compaction	Surface vibrators
iii.	Transporting Concrete	Equipment for conveying concrete will depend on site conditions
iv.	Curing of concrete	Water tanker truck mounted

Table - 4

Plant for bituminous road pavement

No.	Operation		Plant
i.	Surface dressing	i.	Bitumen boiler with sprayer or bitumen pressure sprayer
		ii.	Chip spreader
		iii.	Smooth wheeled roller
ii.	Penetration grouting semi grout/full grout	i.	Bitumen boiler with sprayer or Bitumen pressure sprayer
iii.	Premix carpet	i.	Hotmix plant of capacity, 6-10 T per hour
iv.	Seal coat	i.	Paver finisher
		ii.	Tipping truck

 For work of large magnitude two or more mini hot-mix plants, a paver finisher and tipping truck for haulage form a desirable combination.

..... Table contd.

v.

Hot mixed bitumious macadam or Asphaltic concrete work

i.

Bitumen boiler with sprayer

General Notes:-

   1.  Comparisons between crawler mounted and wheel mounted bulldozers.

	Crawler mounted		Wheel mounted
i.	Delivers greater tractive effort.	i.	Higher travel speed
ii.	Suitable for    operations in loose or muddy soil	ii.	More output
iii.	Can operate in rocky formations without damage	iii.	Causes less fatigue to operators
iv.	Lower pressure under tracks hence greater flotation	iv.	Travels on paved  surface without causing damage
v.	More versatile		No hauling equipment necessary

2. Comparison between oil fired and coal fired/firewood fire

Boilers

	Oil Fired		Coal fired/Firewood fired
i.	Less heating time	i.	Less initial cost
ii.	More thermal efficiency	ii.	unskilled operator can operate
iii.	Better output	iii.	Operation cost is less
iv.	Needs less number of tar/bitumen boilers	iv.	Less efficient as compared to oil fired
v.	Easy to start/shut
vi.	No consumption of fuel when standing idle
vii.	Suitable for any season
viii.	Requires trained operators
ix.	High initial cost

  5.  Comparison between batch type Hot-mix-plant and continuous hot mix plant

No.	Continuous type		Batch type
i.	Supply is continuous and hence output is more	i.	Better control on mix
ii.	Related equipment can also be put to maximum use	ii.	Gives better surface
iii.	Quality of mix can not be controlled precisely	iii.	Less output
		iv.	High initial cost

Classification of Hot mix plants

These are classified on the basis of capacity and their mobility.

1. 3T to 10T per hour capacity mobile or mini-plant

These plants are mounted on pneumatic wheels and can be moved easily. They are suitable for handling small lengths say up-to 10 km. But due to frequent shifting the total output is less. Because of the small capacity paver finisher cannot be used with a single plant but is ideally suited for manual work. Mini-plant of this nature is good for small jobs particularly in the nature of repairing and maintenance.

But mini plants have certain limitations.

i. The feed to the plant is taken from the road side and as such there is no precise control on the quality of output.

ii. Temperature loss is more.

iii. As paver finisher cannot be used with mini-plant and work is done manually the quality of the road surface may not be up-to the mark.

iv. Collection of the aggregate is required all along the road and this may affect gradation of the feed at different locations and as such there may not be uniformity over the entire length of the road.

v. Frequent shifting of the plant is involved in the use of mini-plant.

2. 10T to 45T per hour capacity or Portable plant.

Plant of this type can be easily dismantled and transported by road or rail. With its capacity it can handle road length upto 40 km. i.e. if such a plant is kept at a place it can operate for 20 km. on either side.

3. Up-to 60T per hour static plant.

These plants are installed at a permanent location for a long time. They can supply hot mix up-to a lead of about 30 km. In other words a road length of 60 km. can be easily tackled by a static plant installed at a suitable location midway.

Outputs and performance of the equipment:

Manufacturers of the equipment give output of their products. This however is based on ideal conditions which are difficult to obtain on working site. Naturally the actual output of equipment is different and may vary from site to site.

One of the important tasks of the planner is to assess the requirement of the plant and equipment on a particular job. For this he must know:

i. total quantity of work to be done and

ii. the output of the equipment proposed to be used.

Factors affecting the performance of equipment:

Factors which affect the performance and hence the output of an equipment have to be carefully considered.

Factors related to the job are required to be considered which include:

i. Swell and shrinkage of material handled

ii. Gradient of the haul road

iii. Rolling resistance of the haul road

iv. Climate and topography

v. Tractice efficiency

vi. Moisture content of materials handled

vii. Altitude

In addition to the above factors which more or less have to be accepted as they are on a job there are factors which relate to the way the job is managed. These factors include:

i. how well the operators are trained

ii. layout on job site

iii. proper matching of various allied equipment

iv. availability of the facilities for maintenance, repairs etc.

v. management and worker relationship

The actual output of equipment is a combined effect of factors related to job and to the management. While assessing annual output number of working days (actually the number of working hours) has relevance. Working days depend on the climatic conditions i.e. temperature, rainy season etc. Both these factors influence bituminous work. Assuming normal condition and single shift about 200 working days or about 1500 working hours would be reasonable basis of calculation.

Even though manufacturer indicated details regarding output, fuel/energy consumption, it is always desirable to maintain regular and elaborate records of the time for which the equipment is used, fuel/energy consumed, expenses on repairs and maintenance and output so that useful data in respect of cost per unit output or cost per unit time of use of the equipment etc. can be generated.

Estimating the requirement of the equipment:

Equipment on a road work (or on any work) has either to be purchased, obtained on hire or transferred from some other project. In either of the cases a fairly accurate estimate of the requirement of equipment has to be done so as to ensure that expenditure on equipment is not wasted. This needs planning well in advance.

Factors to be considered are:

i. What is the most desirable sequence of operations involved in the work?

ii. Which of the operations are to be performed by the machinery?

iii. In case some or all equipment is to be transferred from other projects how the programs of both the projects to be arranged so that there is no undue to and from movement of the equipment and at the same time the work is completed in optimum time.

Data required:

Basic data required for estimating the equipment are:

i. Quantities of items of work : Road Project is sub divided in operations like (a) Earth work (b) Aggregate production (c)transporting aggregate to road (d) metalling (e) compaction (f) wearing surface -- concrete/bituminous surface etc. Quantities of items are worked out.

ii. Period of completion of the project.

Period of completion would depend on the duration required for the various constituent items and the sequence in which they are proposed to be executed. Normally a given road work has to be completed in a stipulated period particularly when the work is to be completed on contract. In such cases the duration of the constituent operations have to be adjusted taking into consideration the activity interrelation and overall period of completion. While fixing the activity durations due allowance must be made for bad weather, monsoon, loss of time due to shifting equipment, break down, repairs and maintenance of equipment etc.

iii. Normally no work is possible for 3 to 4 months in a year due to monsoon. Further considering weekly holidays normally 25 days could be considered to be available for working. Though a working day is considered to comprise 8 hours, a part is spent in inevitable operations like shifting, waiting etc. Thus in about 200 days available, working hours would be about 1200-1500.

iv. From (i) to (iii) above a fair estimate of requirement of equipment can be done. Over and above this a suitable provision (to the extent of 10%) is done as stand by to take care of break down or unforeseen circumstances.

Conclusion

It would be obvious from the above details that the planner/estimator should have a good understanding of the work site, methods/techniques of work as well as the characteristics of the equipment, their output, factors affecting the output etc.

Appendix 1 shows the probable life of equipment and machines used on road construction while Appendix 2 shows their output per working day.

Appendix - 1

Approximate working life of the road construction equipment.

No.	Equipment	Working life (hrs)
1.	Stone crusher(400 mm x 225 mm size) capacity 10-12T per hour	10,000
2.	Granulator (300 mm x 175 mm) 4-5T per hour	10,000
3.	Diamond drilling machine	12,000
4.	Tractor Dozer	12,000
5.	Motor grader (3.6 m & above)	15,000
6.	Motorised scraper	12,000
7.	Towed scraper	15,000
8.	Pusher (crawler tractor)	12,000
9.	Soil stabiliser	12,000
10.	Trucks 5T & below	1,50,000
11.	Trucks above 5T	2,00,000
12.	Rear dumper	10,000
13.	Bitumen boiler	10,000
14.	Bitumen mixer	10,000
15.	Bitumen pressure distributor	15,000
16.	Bituminous Hot mix plant	15,000
17.	Paver finisher	15,000
18.	Chip spreader	15,000
19.	Road Roller 8-10T	18,000
20.	Tandem Roller 4-6T	18,000
21.	Concrete mixer 7-10T	8,000
22.	Vibrator	8,000
23.	Air Compressor	10,000
24.	Diesel pumping set	10,000 to 12,000
25.	Truck mounted water tanker	1,00,000

Appendix - 2

Probable output of road construction equipment

under normal conditions of working

No.	Equipment	Average output per day	Remarks
1.	Scraper motorised 9 - 11 cum size	138 - 140 cum
2.	Scraper towed 7 - 8.5 cum size	120 cum
3.	Rollers
	a. on soil	425 cum
	b. murrum and gravel	320 cum
	c. Rubble soling	42 cum
	d. Wearing surface of metal	30 cum
	e. Surface coating 1st coat	650 SQM
	f. Surface coating 2nd coat	930 SQM
	g. 20 mm carpet	465 SQM
	h. Seal coat	930 SQM
	i. Bitumen macadam	280 SQM
4.	Sheeps foot roller Earth work	595 - 600 cum
5.	Soil stabilizer	115 SQM
6.	Hot mix Plant (20T - 30T capacity)	120 T
7.	Paver Finisher (75T - 100T per hour)	450 T
8.	Bitumen Boiler	2250 kg
9.	Stone Crusher (400 mm x 225 mm)	72 cum
10.	Granulator	24 cum
11.	Trucks for transporting materials on well maintained road one way lead 8 km	6 trips
	one way lead 16 km	5 trips
	one way lead 32 km	4 trips
12.	Water tanker
	one way lead 4 km	14 trips