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By C. Vipulanandan

It is critical to monitor the ground conditions during excavation and drilling of boreholes during construction to identify possible changes in the soil and rock formations. Drilled shafts are increasingly used as foundations to support structures, bridges and other facilities in geomaterials such as soft-rocks and hard clays. Locating the bottom of the borehole during construction with the required design strength is critical. Hence developing a simple device that could be easily adapted/used with the drilling tool was of interest in this study. Determining the shear strength of the geomaterial in the borehole and at various elevations including the bottom of the borehole can lead to better quality control of construction by identifying the various layers based on strength. In this study, a down-hole penetrometer (DHP-CIGMAT) was designed, built, calibrated and tested in the field to determine its effectiveness in measuring the strength of soil/soft rock in the boreholes. Based on limited field tests, linear correlations between geomaterial strengths and DHP-CIGMAT deflection have been developed. The DHP-CIGMAT can be used to identify soils and soft rocks.

By Hamed Mirzadeh

The hot working behavior of 17-4 PH stainless steel was studied using the hot compression test at temperatures of 950-1150 °C with strain rates of 0.001-10 s-1. A step by step procedure for data analysis in hot compression test was given. The work hardening rate versus stress curves were used to reveal whether or not dynamic recrystallization (DRX) occurred. At low Zener- Hollomon (Z) parameter, this material showed a new DRX flow behavior, which was called Multiple Transient Steady State (MTSS). At high Z, as a result of adiabatic deformation heating, a drop in flow stress was observed. The general constitutive equations were used to determine the hot working constants of this material. Moreover, after a critical discussion, the deformation activation energy of 17-4 PH stainless steel was determined as 337 kJ/mol.

Jan 1, 2010

"Gravity concentration remains the main separation method for fine iron ore and is used extensively for treating various minerals. Gravity concentration methods separate minerals of different specific gravity by their relative movement in response to gravity and one or more other forces, the latter often being the resistance to motion offered by a viscous fluid, such as water or air (Wills, 2006).Spirals concentrators are one of the gravity concentration equipment used for beneficiation of minerals. Spirals are typically used for processing of fine minerals (-1mm) size fraction. The main operating variables for a spiral concentrator are the feed rate, the solids concentration, the wash water addition and the position of the cutters or splitters used to separate the tailings, middling and concentrate streams (Sadeghi, Bazin & Renaud, 2014).The aim of this study is to investigate the effect of feed rate, solids concentration and wash water on grade and recovery on iron ore material. The Multotec SC20HC/7 WW spiral was used for the experimental test work. The spiral was tested at varying solids concentration and feed rate. The wash water rate was also varied to establish the best washing rate. The splitter positions were kept constant. Optimization of these variables is expected to provide optimum conditions for a good compromise between grade and recovery.INTRODUCTIONSpiral concentrators are simple low energy consuming devices that separate minerals mainly on the basis of density. Spirals are widely used in mineral processing as a method for preconcentration and have proven to be metallurgically efficient and cost effective.Spirals have a wide application, they are used in iron ore processing, coal, gold, chromites, mineral sands, glass sands, and in soil cleaning.Separation on a spiral is achieved through a combination of forces that act on particles as they move down the trough of the spiral. The main forces known to act on the particle on a spiral are the gravitational forces, centrifugal force, hydrodynamic drag, and lift and friction forces (Kapur & Meloy, 1998). Apart from the forces acting on a spiral, the properties of the slurry flowing on a spiral including, solids concentration, feed rate and wash water also plays an important role in the separation on the spiral.The relationship between separation efficiency and feed rate was shown to be linear, with a decrease in efficiency at higher flow rates. Previous work on flow profile by Holland - Batt (1990) indicated that any increase in the feed rate to a spiral results in a greater part of the additional flow volume reporting to the outside of the trough. The flow on the outside of the trough becomes energized and consequence to that the heavy particles find it hard to settle and escape this region to the inner region. This effect has a high impact on recovery of heavy minerals, since any increase in volumetric flow on the spiral is not made available for recovery in the inner region of the spiral."

Jan 1, 2015

By Bjöm Böhle

Top-down construction (or cut and cover construction) is providing important advantages when comparing with conventional construction techniques for commercial developments with deep basements, underground car parks or near surface infrastructure and traffic tunnels. Main features are substantially reduced restrictions to surface usage, avoidance of intervention with adjacent property, provision of rigid substructures resulting in minimal deforma­tions and settlements and, last but not least, accelerated construction pro­gramme. The present contribution illustrates the construction method in general and elaborates in detail on the special foundation works for a major urban commercial high rise development requiring a six level basement structure.

Jan 1, 2006

By Bryn Harris, Liming Huang, Andre Laplante

"This paper reviews flowsheets generally used in gold rooms to upgrade primary gravity concentrates particularly those of Knelsons. It is concluded that even for small operations, which treat between 250 and lo00 kg of concentrates per day, there is a strong economic incentive to include in the flowsheet magnetic removal of tramp iron, at least two shaking tables, screening of either table feed or table tails at 150-212 um, and scavenging of table tails with a small centrifuge. Headroom, rather than floor space, is often inadequate in most gold room designs, and limits gravity flow and flowsheet flexibility. Experimental data are presented to demonstrate the effectiveness of a small Knelson Concentrator to scavenge significant amounts of gold (up to 91 %) from fine table tails.RésuméCet article examine les schémas d’évolution généralement utilisés pour traiter les concentres gravimétriques d‘or, en particulier ceux produits par concentrateur Knelson. Nous en venons à la conclusion que même pour un petit circuit d’une capacité de 250 A 1000 kg/jour pourrait bénéficier des opérations unitaires suivantes : concentrateur magnétique pour extraire la feraille, au moins deux tables A secousses, criblage de l’alimentation ou du rejet d’une ou des tables i une maille de 150-212 um, et épuisages des rejets fins de table avec un centrifuge de petite capacité. C’est l’espace vertical du lieu où se fait cette concentration qui représente la contrainte la plus importante, plutôt que sa surface, puisqu’il faut maximiser l’écoulement par gravite des pulpes et s’offrir une certaine flexibilité quant à l’agencement final des opérations unitaires. Nous présentons également des données expérimentales pour démontrer l’efficacit6 d‘un Knelson de laboratoire pour récupérer jusqu’ à 91 % de l’or contenu dans les rejets fins de table."

Jan 1, 1999

The Department of Mineral Resources has a statutory responsibility for mine site environmental management and control in New South Wales. The Department is focusing on an environmental management systems (EMS) approach, as a management tool to achieve æbest practiceÆ outcomes both within our own organisation and on mine sites. One of the DepartmentÆs tools is environmental risk assessment and management which incorporates the Mining, Rehabilitation and Environmental Management Process (MREMP). The MREMP was introduced many years ago in order to integrate the activities of key stakeholders who may have a material interest in the mine. The MREMP provides an ideal mechanism by which ædue diligenceÆ requirements and environmental management programs can be integrated into mining operations and lead to a sustainable post-mining land use.

Jan 1, 2002

By M. Abdellatif

Keywords: Magnesium, pyrometallurgy, Mintek Extensive testwork on atmospheric thermal magnesium production has highlighted certain important fundamental and operational factors that have a major influence on magnesium extraction and its extraction rate, the condensation efficiency of magnesium, as well as on the quality of the condensed metal. The possible impact of these factors on the selection and preparation of raw materials, recipe choice, furnace electrical energy consumption, and on the refining requirements of the crude magnesium is discussed. Selected pilot plant operational and metallurgical data are also presented.

Jan 1, 2006

In Alaska?s southwest corner, in the Bristol Bay region, 476 holes have been drilled to help define the size of the Pebble Project. The results indicate that the deposit holds close to 32 Mt (72 billion lbs) of copper and 2.9 Gt (94 million oz) of gold. The Pebble Partnership, an Alaskan limited partnership of Anglo American and Northern Dynasty Minerals, owns the project that consists of two world-class mineral deposits. Currently in the prefeasibility and prepermitting stage of development, the Pebble Project is one of the largest and highest profile exploration projects in North America. History The Pebble West Project was originally discovered in 1988 by Cominco (now Teck Cominco). Drilling programs in 1997 defined a near-surface mineral deposit of 1 Gt (1.01 billion st). Minerals found included copper, gold and molybdenum. Northern Dynasty Minerals acquired the property in 2001 and, by 2005, it had confirmed a measured and indicated resource of 4.1 Gt (4.5 billion st) containing 1.2 kt (42.1 million oz) of gold, 11.2 Mt (24.7 billion lbs) of copper and 612 kt (1.35 billion lbs) of molybdenum and additional silver. By September 2005, Pebble East, a deeper, but richer deposit had been found. Drill data by the end of 2005 confirmed a 3.4-Gt (3.7-billion st) inferred resource containing 19 Mt (42.6 billion lbs) of copper, 1.2 Mt (39.6 million oz) of gold and 1.2 Mt (2.7 billion lbs) of molybdenum.

Jan 1, 2009

By Olga Frank-Kamenetskaya

The experimental results of study of atmospheric corrosion processes on Saint-Petersburg bronze monuments surface, received in situ and by means of simulating experiments, have been discussed. Influence of the time factor on corrosion film (patina) mineral composition has been analyzed. Direct dependence between patina mineral composition and environmental conditions has been proved. The sequence of patina phases crystallization has been established. Effect of the chemical composition and heterogeneity of artistic bronze and also monument surface structure on the rate of corrosion process has been regarded. The time variations of mass of the crystallized in the hydrochloric acid vapor phases have been investigated. The kinetic laws of their development at the initial stage of formation, indicating simple (non chain) reactions, have been revealed.

Jan 1, 2006

By A. Bascetin

Waste materials caused by mining activities are an important environmental problem. Paste technology is a good alternative for waste management because it has many benefits in the aspects of environment, cost and safety. Disposal of process wastes in paste form is an attractive option for waste management, as it eliminates or reduces the risks associated with conventional methods. Due to the geotechnical characteristics of the paste, it is very similar to soil materials. So determining the geotechnical properties of the paste material is essential to durability of the paste. The some important geotechnical properties are compressive strength, porosity, shear strength, hydraulic conductivity, water content, consolidation, etc. In this study, the important parameters and the relation between them were investigated and obtained some results which will affect for optimum design of waste management.

Jan 1, 2012

By L. Bergkvist

"History can provide many answers with regard to what today’s mining industry looks like and how we got to where we are today. It has always been self-evident that safety has to be given the highest priority and, throughout history, many mine workers have been injured, become ill and have even sacrificed their lives due to the way in which attempts have been made to extract the ore, often due to ignorance of the dangers being faced. In more recent stages of history we have seen certain dangers being compensated by means of higher wages and bonus systems in order to have the work carried out: one example of this is when the rock heating method was employed and the men who first went underground to put out the fires that were burning, were paid extra. The working conditions, to which these people were exposed, with smoke-filled closed spaces, shortened their life expectancy considerably and today we can ask ourselves whether it is really possible to value these efforts just by higher wages. In all mines worldwide the working environment has been improved and many mining companies have a zero vision where work-related injuries and accidents are concerned. Despite this, incidents of varying severity still occur and a continuous improvement process and ongoing training is necessary in order to constantly minimise risks and improve the working environment. Atlas Copco takes this into account in all its development and we not only review our own production units but also the needs of our customers, with regard to the machinery that is produced in order to cater for customers’ safety and production objectives. Underground mining probably started at the beginning of the 11th century when people with modest tools tried to extract ores that were present in the bedrock. Methodology has developed enormously over the years with a strong focus on increased efficiency and higher production. In different parts of the world the development is driven forwards at different rates depending on which controlling factors are regarded as necessary. Political decisions, profit goals and productivity have partly controlled the development, but the greatest factor where improvement is concerned still remains with increased understanding of the totality. During more than 1000 years since underground mining has been conducted, all individuals at all levels have constantly improved their expertise and the human element has been of great importance with regard to the development that has been made, even though technology often occupies a leading role when we describe the improvements made."

Jan 1, 2011

By Virginia T. McLemore

The Gallinas Mountains are in northern Lincoln County and southern Torrance County, New Mexico, USA where a series of alkaline igneous bodies, including porphyritic latite, trachyte/syenite, andesite, and rhyolite laccoliths, flows, dikes, and plugs, have intruded Permian sedimentary rocks belonging to the Permian Abo, Yeso, and Glorieta Formations. A small amount of bastnaesite, a REE mineral, was recovered during processing for fluorite from the Gallinas Mountains. Four types of deposits are found in the Gallinas Mountains: epithermal REE-F veins, Cu-REE-F veins, REE-F breccia pipes and iron skarn deposits; all are associated with Tertiary alkaline to alkalic-calcic igneous rocks. Alteration includes brecciation, silicification, chloritization, and fenitization. District zonation is defined by Cu-REE-F (±Pb, Zn, Ag) veins that form center of the district, surrounded by REE-F veins. Carbonatites are inferred at depth by the presence of fenitization, carbonatization of the breccias, presence of REE and similarity of the intrusive rocks and mineralization to areas with known carbonatites.

May 1, 2011

By J. Yue

"Mount Milligan mine is located in northern British Columbia. The concentrator employs conventional SABC grinding circuit with bulk sulphide flotation processes. Commissioning started in September of 2013 and nameplate production of 60,000 TPD was reached in the fourth quarter of 2015. As is typical with many mill ramp ups, bottlenecks developed as throughput increased. Since then, plant modifications and new control philosophies in the comminution and flotation circuits have been implemented and evaluated. The mine-to-mill collaboration played a key role in reaching target throughput rates by improving blast fragmentation and implementing temporary pre-crushing. Results of the projects as well as ongoing challenges/bottlenecks and solutions will be discussed.IntroductionMount Milligan Mine is a copper-gold producer located approximately 253 km northwest of Prince George in British Columbia. Production commenced in September 2013 and reached nameplate capacity of 60,000 TPD in December 2015. Average head grades for the mine life average 0.18% Cu and 0.39 g/t Au.Circuit DesignOriginal process design began with run-of-mine ore from the pit crushed through a 60-110 gyratory crusher, conveyed to a live ore stockpile and fed to the mill via four variable apron feeders. The concentrator circuit employs SAG mill - Ball mill - Pebble Crusher (SABC) grinding configuration to grind the ore down to a target P80 of ~200µm. It is then fed to two parallel trains of flotation tanks, each consisting of five 200 m3 tank cells with the first two being roughers and last three being scavengers. Concentrate streams from roughers and scavengers are separately reground with a closed circuit Tower mill and two open circuit ISA mills operating in parallel, respectively.Three stages of cleaners upgrade roughers/scavenger products to 25% Cu followed by a cleaner scavenger stage. The final concentrate is then thickened and filtered to approximately 9% moisture and shipped off site (Figure 1)."

Jan 1, 2017

By Jeffrey Johnson, Carl Sunderman, Ted Williams, Stephen Signer, Douglas Bayer

To measure the loading behavior of friction bolts, researchers at the Spokane Research Laboratory of the National Institute for Occupational Safety and Health (NIOSH) installed strain gauges on the interior of friction bolts and developed a battery-powered miniature data acquisition system (MIDAS) that fits inside the hollow portion of the friction bolt. The advantages of this system are that it is protected from face blasts and eliminates the need for external wiring. Laboratory pull-out tests showed that friction bolts installed in a concrete block with resin were loaded to about 1.8 tons/ft of bolt length; bolts installed without resin were loaded to 1.3 tons/ft. Three strain-gauged friction bolts were installed at Hecla Mining Company’s Gold Hunter Mine, Mullan, ID, in the wall or rib of a mechanized cut-and-fill stope. The object of these tests was to establish an installation procedure for the bolt-and-MIDAS combination and to evaluate performance. The stope was advanced in three 15-ft increments and strains induced in the rock bolts by stress changes in the rock were recorded every 30 minutes. The MIDAS proved to be rugged enough to withstand the shock and vibration from nearby (5 ft) face blasting. Data from MIDAS showed that the friction bolt installed with resin was the most sensitive to each face advance. It showed a steady increase in loading to a maximum value of 1000 microstrain. The friction bolt installed without resin showed stick-slip behavior with loads to a maximum of 400 microstrain before the stope was completed.

The reconstruction of the world after the present war must inevitably be profoundly influenced by the rise and progress of New China.The principle of Chinese mathrity has been admitted by Great Britain and the United States by their abjuration of extra-territorial tights, and by the withdrawal of the Maritime Customs Administration. The United States admits equality by her declaration that Chinese are eligible for American citizenship, and the reaction to this will be swift enmity to such peoples as may impose humiliating restrictions upon Chinese citizens.Finally, the decisions of the Moscow Conference and the recent meeting of National leaders in Cairo give partnership rights to this new State in post-war reconstruction, and open the way for a rapid realization of her destiny.It seems certain that China, if so she wills, can become, within a generation or so, one of the considerable forces of the world. The toad she wiII follow will be lighted by her own inherent and intrinsic genius. Her speed of progress can no longer be forcibly influenced by other nations and the attitude towards her of somewhat contemptuous patronage hitherto adopted by the European communities bordering the Pacific Ocean must be radically modified.It is doubtful whether the European will ever reach full understanding of Chinese mentality. The Chinese "way of life" since the dawn of her civilization has been totally divergent from that of the European, but the enormous potential strength, due to the simplicity of their requirements and their steadfast industry, is a function of that "way of life." On the other hand the trend of reorganization must obviously be towards Western standards; and a wide knowledge of the potential strength of the Chinese is possible and will be essential in our post-war world. The following, necessarily inadequate, notes are therefore offered, as an indication of the obstacles to be overcome and the capacity of the Chinese executives and operatives to overcome them.For 'thirteen centuries the political and social structure of China proper (ie, excluding Mongolia, Manchuria and Tibet) has been rigidly shaped by the philosophy of Lao Tze and the ethics' of Confucius. This Taoism, which is described as the "way of harmony" with its three jewels of character, gentleness, economy and humility, advocates the minimum of social, economic and political organization and still gives the key to the Chinese character.The Mongol and Manchu conquests of the 12th and 17th centuries, respectively, could hardly be dignified with the name of war, but the superior intelligence and harder mentality of the unwarlike Chinese finally absorbed...

Jan 1, 1944

By M. Mirnezami, D. Lascelles, J. A. Finch, E. El-Ammouri

"In a previous publication, the depressant action of Mg above pH 10 on Cu-activated sphalerite was described (Lascelles et al., 2001). In the present communication, a second role, aggregation is introduced.Aggregation (i.e., the tendency of particles to cluster) is measured using settling rate and turbidity converted to an aggregation index (AI) where 0 corresponds to dispersed and 1 to aggregated. Surveys of Cu and Zn flotation stages at four concentrators showed the A1 increased significantly above pH 9. The metal ions identified in the process waters, principally Ca and Mg, were tested to determine which might be responsible. The presence of Mg was found to be the most important, 50 ppm Mg having a greater impact than 500 ppm Ca fkom pH 9 to 1 1. In one plant, poor repeatability in A1 was suspected to be related to varying Mg levels; doping with Mg significantly increased AI.In both aggregation and depression, therefore, the common feature is the impact of Mg at pH > 9. Over this pH range Mg forms a range of hydroxy species, including Mg(OH)2 precipitates. Suggested aggregation and depression mechanisms associated with these precipitates are introduced. Possible problems and opportunities arising from the findings are discussed.INTRODUCTIONProcess waters in flotation circuits contain a variety of metal ions that may introduce unwanted activation or depression. Two common metal ions are calcium and magnesium. Typical concentrations are in the range 50 ppm Mg and 500 ppm Ca (Marticorena et al., 1994, Basilio et al., 1996, Negeri et al., 1997, Nesset et al., 1998)."

Jan 1, 2002

In this address I look back over the past 40 years of mineral exploration in New Zealand û essentially the period since the Second World War (ie since 1945). It was the period of my personal involvement, and indeed of the personal involvement of a number of you. Luckily it was aperiod of great interest and activity. In the previous 50 years, virtually nothing had happened, and it is kindest to draw a veil over that period. In the very important earlier 40 years (1855 - 1895) the New Zealand gold rush occurred. That must have been a fascinating, rewarding period, which has been thoroughly documented by better historians than myself. I will simply comment firstly that its mineral explorers (gold-prospectors) were very successful indeed, and found most localities of the minerals they sought, in spite of using very different methods from ours of today. Secondly, they were preceeded by one of Maori exploration, which searched for a much restricted list of minerals, but succeeded in finding virtually every locality we know of today. The explorers of both of these early periods were obviously highly successful, but, in the time available, I must restrict myself to the period since 1945. I am currently editing the effective up-dating of Gordon WilliamsÆ 'Economic Geology of New Zealand' (1974). It covers the last 12 years or so. Many of you are contributing to that volume û both as authors and as referees û and I would like to take this opportunity of thanking you all. Although this new volume excludes the energy field, many of us have been involved in it, and I am therefore including energy minerals in this review, as Williams did in 1974.

Jan 1, 1987

By Wade Edward Speer

The Hiddenite District of Alexander County, NC has produced some of the world?s finest large emeralds since the first one was discovered 134 years ago. In fact, North America?s largest emeralds come from the district, making this one of the continent?s most unique gem deposits. In addition to emeralds, the Hiddenite District is also famous as the discovery site for the rare spodumene mineral hiddenite, first identified in 1881. Nowhere else in the world do these two minerals naturally occur together. The emeralds are a unique color variety of beryl (Al2Be3Si6O18) with trace amounts of Cr+3 and V+3 substituting for Al+3. The hiddenite (LiAlSi2O6) crystals also exhibit emerald green color due to traces of chromium. Consisting of three large deposits and numerous prospects, the district encompasses an area of 10 km2 (4 sq miles) centered on the small town of Hiddenite. Operations at the Adams, Ellis and North American Emerald Mines properties have been productive at irregular intervals since the 1880s. Currently, only the North American Emerald Mines property is being mined on a regular basis. Recent activity there has exposed a 3-hm2 (7.4-acre) pit with depths of 25 m (82 ft) that provides the best exposures of unweathered bedrock seen in the district in more than 120 years. Although no official records exist, public and private data indicate that the production of the entire Hiddenite District from 1880 to 2007 is about 70,000 carats of emerald and 20,000 carats of hiddenite. The bulk of the emeralds came from the North American Emerald Mine property (NAEM, formerly known as the Rist Mine) where sustained mining replaced the previous sporadic prospecting in 2000.

Jan 1, 2009

By W. C. Lacy

Stratabound copper ore bodies in thick Proterozoic metamorphosed sedimentary and volcanic rocks at the Tong Kuang Yu Mine in southern Shanxi Province of China were considered as possibly being amenable to block cave mining. Initial evaluation of caving characteristics was based upon old calyx drilling records, limited underground mining experience and geological mapping, a few diamond drill holes and measurements in surface subsidence features. Classification and mapping distribution of rock quality types aided in mine design, prediction of fragment sizing and explosive requirements, cave assist and ground support requirements. Comparison is made between early feasibility predictions and actual mine experience.

Jan 1, 1989

By Reda M. Bakeer

"An approach slab is the roadway segment that immediately follows a bridge intended to provide a smooth transition between the two elements. Some approach slabs have developed rough rideability with time due to differential settlement between the roadway embankment and the bridge. Soils in south Louisiana are generally poor and highly compressible and, therefore, pile-supported approach slabs were occasionally used. Timber piles of variable lengths are driven into the soft soils where no appreciable toe support exists. This resulted in the soils both supporting loads through shaft resistance and yet experiencing long-term consolidation settlement. Field testing and review of the records of over 120 approach slabs constructed in south Louisiana yielded the conclusion that their performance is primarily governed by negative skin friction (downdrag) imposed on the relatively short timber piles. A software (TU-DRAG) was developed to evaluate the deflection profile of a pile-supported approach slab based on its geometry and conditions of the underlying soils. It evaluates the effect of dragload considering the number and spacing of the piles at each transverse row and their variable lengths along the approach slab. TU-DRAG was utilized in the design of two transportation related projects which have been in service for more than 10 years.INTRODUCTIONThe problem of differential settlement at bridge approaches or “the bump at the bridge” has been recognized for many years. Research studies (1986, 1989, 1997, 2009 and 2013) by the Transportation Research Board (TRB) and the Federal Highway Administration (FHWA) provided comprehensive evaluations of the performance of bridge approach slabs by assessing their field conditions and construction and maintenance records. Various states have also performed their own studies to investigate the performance of bridge approach slabs. The studies considered various types of structures including soil- and pile-supported approach slabs, integral bridge abutments and open-end abutments. Recommendations were provided for the design of new structures and for maintaining and repairing existing structures. Guidelines were offered regarding tolerable movements of bridges and their foundations based on measurements of vertical and horizontal movements of 580 bridges Moulton (1986). Vertical and horizontal movements greater than 102 mm (4 inches) and 51 mm (2 inches), respectively, were considered intolerable. Tolerable limits for angular distortion (differential settlement to span length) were suggested to be 1/250 and 1/200 for continuous and simple spans, respectively. It was reported that a differential settlement greater than 13 mm (0.5 inch) at the bridge interface would be sufficient to constitute a “bump” requiring mitigation."

Jan 1, 2017