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EGB382 (Week 5)
Material Handling & Inventory
| Question | Answer |
|---|---|
| Characteristics of Civil Engineering Projects | • Capital intensive projects • Reliant on specialised equipment • Reliant on special material |
| Construction Materials - Bulk of materials handled on civil projects are for structural purpose: | • For roadworks: large quantities of earth, processed stone and asphalt based materials • For structures: concrete, fabricated steel, reinforcing steel, permanent equipment, cladding |
| Construction Materials (1) | • Characterised by weight and large physical dimensions • Equipment to handle materials is therefore heavy and physically large |
| Construction Materials (2) | • This is reflected in demand for specialised equipment and temporary access • Provision of these materials commonly constitutes a large component of the cost of civil structures (~60%) |
| Construction Materials (3) | • Difficult to arrange deliveries at the precise time of usage. • On-site storage areas are required. • Care needed to prevent degradation of materials in transit and in storage |
| Construction Materials (4) | • Produces a constant demand for onsite movement of materials. • Temporary storage areas required across large sites to minimise time and costs for rehandling |
| Materials Supply Chain | • Many players involved • Many points of failure • Cost uncertainties on many levels |
| Construction Materials - Summary | • They are a large component of the projects • Their availability can be an issue • Qualified(?) suppliers are a necessity |
| Storing Materials (1) | • To believe that materials can be delivered to site with exact timing is naive. (“Just in Time” concept) • It is therefore necessary to provide storage for many different types of materials |
| Storing Materials (2) | • Some require storage out of weather (cement, equipment to be installed, timber, form ply, glass, paint) |
| Storing Materials (3) | • Others may be stored in the weather with care (fabricated steelwork, heavy timbers, reinforcing steel, precast concrete products) |
| Storing Materials (4) | • Similarly, some equipment requires storage under cover (small air hoses, small fittings and hand tools, consumables) • Storage out of weather does not necessarily mean in a building |
| Storing Materials (5) | • Cement is best stored on an elevated platform under tarpaulins • Timber stored clear of ground, spaced and covered with plastic |
| Storing Materials (6) | • Equipment stored clear of ground and covered with tarpaulins • Formply stored clear of ground and covered with plastic – particularly edges |
| Storing Materials (7) | • Fabricated steelwork stored clear of ground and on slope to avoid ponding water • Reinforcing steel clear of ground and contamination by dirt |
| Storing Materials (8) | • Precast products need no weather protection • Prestressed members must be supported only at designed locations |
| Storing Materials (9) | • Small equipment stored in tool shed (with a equipment register – process for sign in and out, tag for safe use, etc) |
| Storing Materials (10) | • In all “laydown” areas ensure adequate room around members for crane access and support • Avoid multiple layers to enable easy recover when erecting |
| Basics of Inventory | • Why do we need to hold inventory? - Productivity fluctuations, material availability issues • Construction supply chains are fragmented and projects can take years to complete |
| Inventory Management (1) | • Why do we need to manage inventory? - Direct and indirect costs - Any examples? • Holding inventory is a trade-off between inventory costs and overall system responsiveness |
| Inventory Management (2) | • What is the optimum inventory to be carried? • Can we carry no inventory? - i.e. Just-in-time delivery |
| Economic Order Quantity (EOQ) (1) | • This is a theoretical computation of how much inventory should be hold. • There are assumptions and simplifications that you need to consider |
| Economic Order Quantity (EOQ) (2) | • Assumptions - Replenishment occurs instantaneously - Demand is constant and non-stochastic - Setup cost S is fixed, independent of order quantity |
| Economic Order Quantity (EOQ) (3) | Variables: • Setup cost S • Annual Demand D • Holding cost H • Order Quantity Q • Unit Cost C |
| Economic Order Quantity (EOQ) (4) | Setup costs: - Paperwork, employee time etc. Holding costs: - Cost of physical space - Taxes, insurance - Spoilage, deterioration - Opportunity costs of alternative investments |
| Safety Inventory (1) | • Can we accurately determine how much inventory we need? • What if we overstock raw materials for a construction project? • What if we understock the necessary materials? |
| Safety Inventory (2) | • What is the demand was stochastic • If we had enough materials to match the average demand, half the time you would run out. • Safety inventory: Inventory carried for “unexpected demands” |
| Over/Under Stocking | • What are the costs we incur if we overstock? • What are the costs we incur if we understock? • New terminology - Cost of overstocking (Co) - Cost of understocking (Cu) |
| Security & Legal Ownership of Materials - Ownership (1) | • Once materials are delivered to site, the Client has a claim on ownership • This claim is strengthened by payment for “materials on site” |
| Security & Legal Ownership of Materials - Ownership (2) | • This gives rise to moves by defaulting contractors, or contractors claiming non- payment, to take materials off site (equally applies to subcontractors) |
| Security & Legal Ownership of Materials - Ownership (3) | • Sometimes necessary to guard materials on site • Payment for materials on site should be accompanied by a schedule of items and quantities covered by payment |
| Security & Legal Ownership of Materials - Client Supplied Materials (1) | • Specialised materials or those with a long supply lead time, are often supplied by client (‘Principal Supplied Items’ • Responsibility for protection passes to constructor upon delivery to them |
| Security & Legal Ownership of Materials - Client Supplied Materials (2) | • Constructor is required to inspect for quality and quantity and to assume responsibility for acceptance |
| Security & Legal Ownership of Materials - Client Supplied Materials (3) | • Contractor is entitled to apply a profit margin to the value of materials. • Handling costs are deemed to have been included in the contract amount |
| Security & Legal Ownership of Materials - Agency Restrictions | • Environmental Protection Authorities (DEHP in Qld) - Restrictions on the area you can clear or impact upon adjacent to your construction site • Energy Authorities (Ergon, Energex, etc) - clearance to power lines, poles, protection required, etc |
| Security & Legal Ownership of Materials - Agency Restrictions - Department of Main Roads | - Use of roads for transport of heavy loads, wide vehicles - Closure/part closure of roads for construction in/adjacent to road (water mains, road upgrades, etc) |
| Security & Legal Ownership of Materials - Agency Restrictions - Councils | • clearance to utility services (water and sewerage pipelines, etc) • Closure/part closure of roads for construction in/adjacent to road (water mains, road upgrades, etc) |
| Security & Legal Ownership of Materials - Agency Restrictions - Telstra | • clearance to services including fibre optic cables |
| Security & Legal Ownership of Materials - Agency Restrictions - Railways | • clearance to HV power • work near tracks (impacts/plans required, QR track supervisor) • changing train schedules for major work near tracks (minimum 6 month lead time and then changes restricted) |
| Site Movements and Traffic Management - Traffic Management Plans (1) | • for project site • use of local roads • construction sequencing with partial road closures • normally required as part of your construction tender (reflects your construction methodology |
| Site Movements and Traffic Management - Traffic Management Plans (2) | MUTCD (Manual of Uniform Traffic Control Devices) – Part 3: Traffic Control for works on road (available on Canvas) |
Created by:
Asher - S
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