Stolz J.M.,Jacobs Associates
2012 Proceedings - North American Tunneling, NAT 2012 | Year: 2012
Consider the concept of establishing an optional bid item that compensates the bidder for assuming responsibility for some or all subsurface conditions. The majority of disputes in underground construction tend to focus on ground behavior - a problematic issue since ground behavior is a function of both owner-responsible subsurface conditions and contractor-responsible means and methods. This concept may offer a viable alternative to the contentious, claims-prone process of allocating the degree of responsibility for ground behavior to each party, but it requires input and buy-in from the industry.
Stolz J.M.,Jacobs Associates
North American Tunneling 2010 Proceedings, NAT 2010 | Year: 2010
There are few industry guidelines that help owners better understand the cost estimates upon which project budgets are based. This paper begins by briefly amplifying the industry consensus that cost estimates for heavy civil and tunnel projects must be based on a "bottom-up" approach. The main focus is on explaining the categories of indirect costs typically used by contractors and their perhaps surprising contribution to overall cost. It then moves on to emphasize the need for an integrated project schedule that quantifies the duration over which these indirect costs are incurred. The paper concludes with a brief examination of and recommendation on the issue of estimating accuracy. These are some of the issues often overlooked when owners review a cost estimate.
Sparks K.,Jacobs Associates
AACE International Transactions | Year: 2012
This paper discusses the role of project cost and schedule control in the planning, contract preparation and execution of a construction project and how proper management of these stages can help manage claims and delays if and when they arise. Starting with the role of the project controls professional during the development phase, this paper will describe how proper cost, schedule, risk management and earned value techniques can be used to properly plan and budget the project. From the planning stage review and support in the preparation of the Division 1 specifications the project controls professional can provide managers with a meaningful baseline and tools to enforce contract requirements. As delay and claim issues occur, proper planned and executed project controls measures will allow owners and contractors to quantify compare these contentious issues.
Davidson G.W.,Jacobs Associates
Proceedings - Rapid Excavation and Tunneling Conference | Year: 2013
The Port Mann Main Water Supply Tunnel will increase Metro Vancouver's capacity to accommodate future regional growth while also improving overall system reliability. The project calls for construction of a 1,000 m long tunnel under the Fraser River between Coquitlam and Surrey in British Columbia, Canada. The tunnel, mined between two approximately 60 m deep vertical shafts, will be constructed using EPBM methods, and will be approximately 3.5 m in diameter. The tunnel alignment is located below the depth of riverbed scour and is designed to remain functional following the Maximum Credible Earthquake. This paper presents the project from planning through design completion, and describes some of the unique technical challenges encountered.
Gates W.C.B.,Jacobs Associates
47th US Rock Mechanics / Geomechanics Symposium 2013 | Year: 2013
Selection of the appropriate bonding agent for rock anchors is critical to the outcome of the job. The author has observed several projects where rock anchors have failed because the wrong bonding agent was used. Examples include failures in vuggy weak limestone as well as very strong granitic rock. Contractors tend to select resin grouted rock anchors (RGRA) because they are faster, cleaner, and simpler to install, requiring less curing time, a shorter bond zone, one grout cycle, and are economical. The problem is that there are some major disadvantages with RGRA. The resin bonding agent performs poorly in weak, broken and vuggy rock because the resin cartridges require a tight borehole to achieve proper mixing and bonding between the rock and the anchor and don't account for extra voids in the rock around the anchor. Loss of the resin into the voids creates gaps along the anchor and reduces the bond strength. As an alternative, cement grouted rock anchors (CGRA) tend to be more reliable in weak, vuggy, porous rock. Because of the inherent problems with RGRA, the author recommends CGRA because one can achieve a stronger bond in weak, fractured and vuggy rock or poorly drilled holes. The pumped grout tends to flow into the voids around the anchor and form a stronger more secure bond. Copyright 2013 ARMA, American Rock Mechanics Association.