Earth Works Road Construction

Earthworks – Loading and Hauling Material

Equipment Most Commonly Used

Where haul distances render dozer operation uneconomical, material is moved either by loading into trucks or by means of scrapers.

A  variety  of  trucks  is  available  for  hauling  loose  materials  on  earthworks  jobs  as  well  as  the conventional  highway truck, there are off-highway  vehicles which  have  fewer axles than their highway counterpart and whose axle loads exceed the regulation limits.

(a)  Highway Trucks  with  general  purpose  tipping  bodies  are  suitable  for  the  cartage  of materials  from  outside  sources  to the  site  of  work,  and  for  the  cartage  and  distribution  of material on the site.

They can operate at comparatively high speeds on the site but require a reasonably firm and smooth ground surface. As they bog easily they are unsuitable on soft sites.

Their  main  application  is  for  very  long  hauls  where  haul  roads  are  good  and  axle  load limitations apply (e.g. for hauling selected fill from a pit outside the limits of the works).

(b) Off-Highway Trucks  are suitable for hauls of up to 3 km at relatively high speed on good haul  roads  but  at reduced  speed  when  working  on  soft  ground. They  are  usually  the  most suitable equipment for hauling shot rock (unless the lead is very short in which case a dozer might be used).

Their axle loads are usually high and, unless they are equipped with abnormally large tyres they may bog on wet sites. Also, one large vehicle may do more damage to a haul road than several small ones.

Their  larger  body  offer  a  bigger  loading  target  for  the  loader  bucket  which  may  increase production of the loader. The high sided body of some of the larger wagons may however, be unsuitable  for  some  types  of  loaders.  (This  possibility  should  always  be  investigated  when matching loaders and trucks).

Owing  to  their  large  capacity  they  are  more  economical  than  smaller  machines  under conditions where they can develop their speed and where they are not delayed by restrictions at the loading and tipping points, but the breakdown of a large carrying unit causes a greater proportional loss of output than that of a smaller unit.