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Property, plant and equipment (Tables)

12 Months Ended

Mar. 31, 2013

Property, Plant and Equipment [Abstract]

Property, plant and equipment

Depreciation for each category is calculated based on the cost, net of the estimated residual value, over the estimated useful life of the assets on the following bases and annual rates:

Assets		Basis		Rate
Heavy equipment		Straight-line		Operating hours
Major component parts in use		Straight-line		Operating hours
Other equipment		Straight-line		5 – 10 years
Licensed motor vehicles		Declining balance		30%
Office and computer equipment		Straight-line		4 years
Buildings		Straight-line		10 years
Leasehold improvements		Straight-line		Over shorter of estimated useful life and lease term

March 31, 2013		Cost				Accumulated Deprecation				Net Book Value
Heavy equipment		$	259,711			$	96,046			$	163,665
Major component parts in use		58,763				23,512				35,251
Other equipment		25,193				9,970				15,223
Licensed motor vehicles		28,862				22,996				5,866
Office and computer equipment		13,931				11,488				2,443
Buildings		4,015				2,943				1,072
Leasehold improvements		9,512				5,682				3,830
Assets under capital lease		59,160				12,264				46,896
		$	459,147			$	184,901			$	274,246

March 31, 2012		Cost				Accumulated Deprecation				Net Book Value
Heavy equipment		$	347,699			$	124,982			$	222,717
Major component parts in use		74,444				28,741				45,703
Other equipment		35,736				17,017				18,719
Licensed motor vehicles		27,120				19,775				7,345
Office and computer equipment		13,438				8,977				4,461
Buildings		4,355				3,235				1,120
Land		281				—				281
Leasehold improvements		6,620				2,232				4,388
Assets under capital lease		16,579				8,538				8,041
		$	526,272			$	213,497			$	312,775

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- Definition

Tabular disclosure of the useful life and salvage value of long-lived, physical assets that are used in the normal conduct of business to produce goods and services and not intended for resale. Examples include land, buildings, machinery and equipment, and other types of furniture and equipment including, but not limited to, office equipment, furniture and fixtures, and computer equipment and software.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 13

-Subparagraph b

-Article 5



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Principles Board Opinion (APB)

-Number 12

-Paragraph 5

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.



Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 360

-SubTopic 10

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229



Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.13)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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