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By Thomas H. Holley

This presentation will describe the underground excavation at the Bad Creek Pump Storage project. It consists of approximately 3,650 m of various size tunnels ranging from 4.2 m to 9.0 m finished diameter, a powerhouse cavern 45 m high by 135 m long by 22.5 m wide, and 422 m of 9 m diameter shaft. A total of 350,000 m of rock will be excavated, hauled, and placed in a submerged wier. Temporary rock support consisting of shotcrete and/or rockbolts is installed as required.

Jan 1, 1987

By C. O. Bounds

The performance of AB5-type alloys for hydrogen absorption including the electrochemical absorption as an electrode for rechargeable batteries has been demonstrated' to be a complex function of the composition, microstructure and surface condition. The compositional studies have focused primarily on substitutions for Ni on the B-site (e.g. Co, Al, Mn, etc.). This current study examines the effect of rare earth substitutions for La on the A-site and considers both other "light" rare earths (Ce, Nd, Pr) and "heavy" rare earths (Dy, Sm, etc.).

Jan 1, 1997

By Robert J. McNally

There are three primary plant nutrients-nitrogen, phosphorus, and potassium--expressed in any fertilizer compound as percent N, percent P2O5, and percent K20, in that order. This article will be concerned with the first two. The chief source of P205 is phosphate rock. As found in the western states phosphate rock is essentially tricalcium phosphate-calcium fluoride (fluorpatite). As such, it is quite water insoluble. The principal phosphate fertilizer used is single superphosphate, produced by reacting sulfuric acid with phosphate rock in the proper proportions.

Oct 1, 1956

By Grover J. Holt

A DETAILED description of the many variations in iron mining and transportation practice in Minnesota would require much space. Since a fairly detailed description of the practices then in use was published in the guidebook issued in connection with the meeting of the Institute on the iron ranges in I920, and subsequent developments have been described by E. E. Hunner,1 M. H. Barber,2 and A. E. Anderson, J. M. Riddell and G. J. Holt,3 it will not be necessary here to do more than review the highlights of current practice. Details on any points of interest can be obtained through correspondence with the operators involved. [T] The iron ores of Minnesota, which have been formed through enrichment of the iron formation in which they occur, largely by the removal of silica, are usually covered by a blanket of glacial drift known locally as "surface." Surface material, including sand, clay, hardpan and boulders, makes up the greater portion of the stripping in open-pit operations. In some instances, stripping also includes taconite and "paint rock," directly below the surface material and overlying the ore. Taconite is the iron formation, a ferruginous chert with interbedded slate layers. "Paint rock" is a local term for oxidized slate layers interbedded in the iron formation, high in phosphorus, alumina and moisture. The iron ores fall into two classes: (I) direct shipping (merchantable ores or ores requiring no treatment except possibly crushing or screening to make an acceptable sized product), and (2) ores requiring beneficiation (such as sintering, drying, washing, jigging, high-density treatment, or magnetic separation in the case of magnetite). The Mesabi Range produces chiefly soft Bessemer and non-Bessemer ores. The Cuyuna Range produces mainly low-manganese brown ore and high-manganese black ores, with some iron ore. The Vermilion Range yields mainly Besse¬mer and non-Bessemer iron ore, with some hard or lump ore that finds use in the open hearth. Open-pit mining is limited to the Mesabi and Cuyuna Ranges but underground mining is done on all three. The choice of mining methods is determined by the relative economics of overburden¬-removal and shaft-mining costs. STRIPPING PRACTICE Common practice has been to remove the bulk of the overburden during the winter season and to mine during the summer. In the present emergency many operators are forced to forego the economies attained by year-round utilization of equipment and to equip for, and carry on, stripping and mining simultaneously. In the normal years or lean years to come, most properties probably will be over-equipped and high depreciation charges will have to be absorbed.

Jan 1, 1942

ARTICLE I NAME AND OBJECT SEC. I. This Institute is incorporated under the Membership Corporations law of the State of New York; its corporate name is American Institute of Mining and Metallurgical Engineers, Inc.; and its objects are such as are stated in its Certificate of Incorporation. ARTICLE II MEMBERS SEC. 1. The membership of the Institute shall comprise four classes, namely: 1. Members; 2. Honorary Members; 3. Associates; 4. Junior Associates. All members shall be equally entitled to the privileges of membership, excepting that Honorary Members, Junior Associates, and Members and Associates whose residences shall be outside of the United States, Mexico, and Canada shall not be entitled to vote. Members and Associates residing within the United States of America, Mexico, and Canada, .and not in arrears for dues, shall be entitled to vote in person at the meetings of the Institute, or, as hereinafter provided for, by letter ballot. SEC. 2. Members shall comprise all those persons who on the third Monday of February, 1918, were members of the Institute, and in addition thereto, all those thereafter elected or transferred into the class of Members. A person to be eligible for election or transfer into the class of Members must be at least 27 years of age and must have had at least six years' employment in the practice of engineering, mining, geology, metallurgy or chemistry, during at least three years of which he must have held positions of responsibility in one or more of these fields. Graduation from the scientific course of a college, approved by the Committee on Membership, shall be considered equivalent to two years' employment, as required in the previous sentence. Employment as a teacher of engineering, mining, geology, metallurgy or chemistry, if in direct charge, may be considered a position of responsibility as specified in the second paragraph. Persons employed in research or any scientific literary work or in teaching in the scientific departments of colleges, approved by the Committee on Membership, who at the same time are engaged in consulting or in the active practice of mining, geology, or metallurgy, shall be entitled to consider the time so spent in active practice as equivalent to an equal length of time of employment in positions of responsibility, provided the work done or the positions held seem to the Committee on Membership to warrant the equivalency. The requirement of three years' employment in positions of responsibility maybe waived by the Committee on Membership in the case of persons who have done notable original work in mining, geology, or metallurgy, or have won distinction by

Jan 1, 1925

By N. A. D. Parlee

THE gas-liquid metal diffusion cell technique1-3 has been used to study the diffusion of nitrogen in Fe-C alloys. The actual apparatus and technique were the same as employed by the authors to study the diffusion of hydrogen in liquid iron.' The diffusion cell' was formed by immersing an alumina tube in a stagnant melt contained in an alumina crucible. The tube (hereafter called absorption tube) contained nitrogen gas at 1 atm and was connected to a sensitive gas-measuring system. The change in the average concentration of nitrogen in the melt in the absorption tube was determined by measuring the rate of absorption of nitrogen in the diffusion cell. Eq. [I], 1-3 derived from the appropriate solution of Fick's second law, was used to examine the data and to calculate chemical diffusion coefficients (D) in situations where the absorption appeared to be controlled by diffusion in the liquid: where V is the stp volume in cu cm, d is the diffusion cell diameter in cm, p, is the density of the melt in g per cu cm, pg is the stp density of nitrogen in g per cu cm, C, is expressed in wt pct, D is in sq cm per sec, and t is in min. According to Eq. [I], a plot of v vs vt should yield a straight line passing through the origin if absorption is controlled by diffusion in the liquid. The slope of this line could be used to determine the value of D under appropriate conditions. As discussed in earlier reports,1,2 the initial thermal expansion of the gas upon immersing the absorption tube distorts the line in the initial stages of a diffusion experiment. However, this is not a serious problem since the slope of V vs 6 plots can be determined from the data points obtained after the initial expansion ceases. The volumes reported on the data plot presented here represent absorption after this thermal expansion ceased. Several preliminary diffusion experiments were attempted with melts of pure iron and with Fe-C alloys containing up to 0.6 pct C. In these cases, no or very little absorption was observed. The only data obtained were for an Fe-C melt which was in addition thoroughly deoxidized by successive hydrogen and vacuum-degassing treatments. These treatments introduced an appreciable amount of aluminum into the melt and reduced its omgen content. The original charge material for this melt contained 0.23 pct s and approximately 0.001 pct &. After repeated hydrogen and vacuum-degassing treatments two diffusion experiments were performed. The analysis of the melt

Jan 1, 1968

By Stafan Rose, Art Madsen

Four years ago, Peabody’s North Antelope Rochelle Mine (NARM) site started experimenting withANFO and Liners in its Cast Blasting operations. The motivation to use ANFO was based on the following:1. ANFO generates more gas thereby resulting in greater heave/movement. 2. ANFO is a more consistent product because there are less components/ingredients. 3. ANFO when protected from water contamination does not produce NOx smoke.

Jan 1, 2007

By John Turney, John Gathje, Donald Gale

The Eskay Creek deposit, located in northern British Columbia, is a high-grade gold/silver ore associated with complex polymetallic sulfides. Process development began in 1989 and continued through 1993. Because of the refractory nature of the ore, options including roasting and smelting were investigated. The selected process of pressure oxidation was the basis for basic engineering design until a re-evaluation of economics and risk indicated a preference for toll smelting. Although well proven in many industrial applications, pressure oxidation of the Eskay Creek ore dictated several innovations to solve problems associated with silver jarosite formation, preg-robbing, and high soluble copper and zinc concentrations.

Jan 1, 1995

By Michael Robert Hodson

I. Introduction The free market cash price of aluminium in the third quarter of 1985 is approximately $1000/tonne, well below the short as well as the long run marginal costs of production. The current disparity between marginal costs and price, as well as the pattern of prices since their high level in 1980, has led many economists to question whether prices are governed by the 'fundamentals'. Prices, some would argue, are the result of speculation; and speculation is irrational, little influenced by the fundamentals of the industry. The object of this paper is first to examine the relation between the fundamentals and price. A number of simple models are formulated and some empirical evidence is given to show that prices are not very different from costs. There are good reasons why costs and prices have fallen since 1980. Second, the connection is drawn between the fundamentals and speculation. To do this the concept of 'rational expectations' is defined and applied to a model of the aluminium industry. Then speculation is introduced into the model and the characteristics of the solution are examined. The object is to discover the new factors that determine prices and the basic change in the nature of the solution that is caused by speculation. 2. Prices and the Simple Supply-Demand Model Consider a simple model of the aluminium industry. Demand, D, is determined by economic activity, A, given exogenously, and inversely by the price, P. Supply, Q, is determined by the inverse of the rnarginal cost curve, and so varies inversely with exogenous factor costs, C, and directly with price. Price is determined by the equality of supply and demand. Given the equilibrium level of demand, price in this model is equal to the rnarginal cost of producing the required level of demand, P = MC (Dl. Algebraically, [ ] How well does this simple model explain the change in prices during the last five years? Table I shows the LME cash price and the estimated marginal cost of producing consumption during the second quarters of 1980 through 1985. The figures in the table show that price and the marginal cost of supplying demand both fell between 1980 and 1982, rose in 1983 and by 1985 had fallen again. Only in 1984 is the direction of change different. And during the 1980 to 1985 period, marginal costs fell by approximately $560/tonne while the LME cash price fell by $678/tonne. There is a correspondence between the fundamentals of cost and price over most of the individual years and the period as a whole.

Jan 1, 1986

By R. H. Wightman

THE following paper describes current mining practices of the Riverside Cement Co. at its Crestmore plant, Riverside, California. For a number of years the Riverside Cement Co. obtained its raw materials by surface quarry operations but after these deposits were exhausted for equipment available at that time, the company started underground mining. Mine workings were begun in 1927 to 1930 for the recovery of limestone by block-caving methods. GEOLOGY The bed of limestone that is being worked is a metamorphosed and recrystallized limestone, which is generally white in color and from medium to coarsely crystalline. This bed is fissured by water courses that vary from minute cracks to large areas. The bed has also been cracked by intrusions along the footwall and hanging wall. These walls are coarse-grained, gray, quartz granodiorite. The strike of the deposit is north and south and it dips to the east at an angle of approximately 50º. The bed is approximately 1700 ft. long, 270 ft. thick at right angles to the dip at the middle of the deposit and tapers to a thickness of approximately 100 ft. at each end. MINING METHODS The mine layout consists of four main levels with elevations as follows: 892 Collar of shaft. 800 Manway level used for ventilation, prospect purposes and as an entrance into the stopes. 700 Mining level where all material is extracted and on which are located the tapping grizzlies. This is the elevation from which all main cutoff stopes and undercutting work is started. 660 Haulage level where the limestone is drawn from transfer raises into the cars and is transported to the tipple by electric locomotives. 633 Level where all water is collected and which keeps the general water table below the working levels. A detailed description of the mine was given in U. S. Bureau of Mines Information Circular No. 6795, in June 1934. Current Block Development The first blocks to be caved were developed very much after the procedure followed in the copper mines of Arizona. This paper covers the ninth block to be caved. With a hard, tough rock like our limestone, it was found that some alterations in the development and control of draw in caving were necessary to secure better crushing effect and provide more safety for such secondary blasting as is required. Sequence of Block Development I. The fringes of the 800-ft. manway level are driven to confirm the diamond drill information and serve to determine the final location and development required for the block (Fig. I).

Jan 1, 1944

By D. Turnbull, J. H. Hollomon, J. C. Fisher

UNDERSTANDING of the diffusion problem has recently been furthered by the analysis of Birchenall and Mehl.1 They pursued the problem of the variation of the diffusion coefficient with composition for non-ideal solid solutions. Their analysis follows the tradition of Wagner,2 Jost,3 Dehlinger,4 and Darken,' who assumed the net flux of dif¬fusing material to be proportional to the gradient of a quantity related to free energy. The basic assumption in Birchenall and Mehl's formulation of the problem is that the net flux of diffusing material is proportional to a thermodynamic activity gradient. To estimate the applicability of the derived relations, they corrected the diffusion coefficients of carbon in austenite by utilizing Smith's' activity data for carbon, and the diffusion coefficients for zinc in copper with activity data computed from the vapor pressure measurements of Hargreaves.7 The corrected coefficients for carbon were virtually independent of carbon concentration. For the diffusion of zinc in copper a moderate variation of diffusion coefficient with concentration remained after the correction. The problem of diffusion can be formulated in another way than that used by Birchenall and Mehl. The method is that of chemical rate theory and has been used by Eyring and his coworkers8,9 as well as by Eyring and Zwolinski10 in a discussion to Birchenall and Mehl's paper. As yet the method has not been applied to substitutional solid solutions. On the basis of their assumptions, Eyring and Zwolinski derived a relation between the diffusion coefficient and activity that is identical with that of Dehlinger and Darken but which does not correct for the variation of the diffusion coefficient with concentration as well as does the relation derived by Birchenall and Mehl. It was thought that the theory of diffusion would be more complete if the inconsistency between the two analyses could be rationalized and if diffusion in substitutional alloys were analyzed on the basis of the concepts of the chemical rate theory. CHEMICAL RATE THEORY According to the theory of absolute reaction rates8 the reaction [A,+A2+ ... +.A;->X,+X2 +...+X; EqI] is viewed as taking place in two steps. First the reactants A1, A2, . . . A[i] combine to form an activated complex M with which they are in equilibrium; [A, + A2 + .. . + Ai = M. Eq 2] Second the activated complex decomposes to give the products X1, X2. . .. X[j]; [M->X1+X2+ ... +.X;. Eq3] It has been shown8 that the number of activated complexes decomposing per unit volume per unit time is given by the expression† [kT]

Jan 1, 1948

By Tiany Guedes Cota

A indústria cerâmica utiliza as argilas como matéria-prima para fabricação de cerâmica vermelha, branca, de material refratário, entre outros. Possuem um vasto campo de aplicação devido às suas características que, em geral, são decorrentes de sua composição química e do processo de fabricação que lhe originou, tais como: temperatura de queima, proporção dos componentes e granulometria da matéria-prima utilizadas. Comumente vem sendo realizada a substituição de parte da massa argilosa por resíduos industriais, para aproveitamento de materiais, diminuição de custos e impacto ambiental. Nesse presente trabalho, foi realizado um planejamento fatorial em dois níveis das variáveis de adição de pó, temperatura de queima e pressão de compactação nas propriedades de densidade, retração linear de secagem (RLS) e de queima (RLQ). A coloração final também foi um parâmetro analisado. A temperatura parece ser a variável que mais influenciou nos resultados de densidade e RLQ. A pressão de compactação dos corpos de prova não foi uma variável significativa na densidade, RLS e RLQ. Logo, a condição ótima para fabricação dos corpos cerâmicos foi com incorporação de 10% de pó de despoeiramento em substituição ao solo argiloso e temperatura de queima de 1000°C.

Aug 17, 2017

By Edward R. Borcherdt

When one considers the advancements made during the 25 years prior to the late fifties, and compares these advances with the progress made in the past decade, the comparison is indeed startling. It was not until 1935 that trucks began to replace rail as a major hauling facility, Initially, the haulage capacity of end dump trucks was limited to 18 or 20 tons. "Straight stick" transmissions were utilized and the available horsepower was minimal. In the early forties single planetary axle 25 ton trucks were introduced, and shortly thereafter those were followed by 35 ton tandem axle units.

Jan 1, 1967

By Walter Kauenhowen

GeRmany's crude-oil production during 1936 totaled 3,112,494 bbl., an increase of 5.2 per cent over the 3,007,711 bbl. produced in 1935. The official monthly production figures published in 1936 report only the individual production figures of the three old established fields, whereas since 1936 official reports combine the production of all other fields into one figure. According to these published data, and using a conversion factor of 1 metric ton equaling 7 bbl., the oil production of Germany in 1936 was as follows:

Jan 1, 1937

By Lawrence Adler

Any design of a mine roof in bedded deposits which ignores differential deflections at the supports can quickly lead to dangerous overstressing. As illustrated by the typical case presented on page 1029, if one support deflects only 0.1 in. more than its neighbor, stresses 50 pct higher than anticipated will result. Previous studies1-3 have assumed that the mine roof acts like a beam clamped at both ends, with no deflection or slope4 at the supports (Fig. 1). Essentially this assumes:5,6 [BA = OD = 0 and dA = dB = 0.]

Jan 10, 1959

By Lowell B. Page

The White River Shale Project has completed a 5,000-foot production decline and a 30-foot diameter 1,010-foot deep shaft into its oil shale orebody in the Uinta Basin of eastern Utah. This is the first major underground access into these Green River deposits in this basin and provides an opportunity to establish and monitor in-situ rock mechanics stations as input to the mine engineering and planning of this large opening, high-tonnage mine. This paper discusses the history, mine development, and rock mechanics planning for this project.

Jan 1, 1984

By John Henry Harden

IN 1874, with Mr. H. Y. Attrill, of Baltimore, Md., I made an examination of some property at Goderich with reference to sinking for and mining salt. With this end in view we visited all the wells in the neighborhood, but the information sought being of so unreliable a character I advised the putting down of a borehole on the property. This has since been done, the result of which has lately been published by Dr. T. Sterry Hunt in the Toronto Globe. From this there appears to have been passed through six beds of salt of an aggregate thickness of 123 feet. Rock-salt was known to exist, for, by the boring of existing wells, small crystals had been brought to the surface in the dirt, but no attempt had before been made to obtain a reliable sample or to prove the number and thickness of the beds. The question now remaining for discussion is, shall the present method of obtaining the salt be continued, or shall the beds be won by a shaft in a regular mining fashion, by which means the salt may be gotten in a condition almost ready for the market? The present mode of obtaining salt is by boreholes from 6 inches to 8 inches in diameter drilled to the beds, into which is inserted a pump. The "feeders" of fresh water intersected in drilling the well are allowed to descend on the outside of the pump-tube to the salt beds and there become saturated, when, on use of the pump, brine is obtained for evaporation. In the beginning brine can only be had in limited quantity, but by the daily application of the pump, and the gradual solution of the salt, a larger surface becomes exposed to the action of the fresh water, and a continuous supply of brine is obtained. It will then be understood that the supply of brine is dependent upon the feeders of fresh water intersected in boring the well, which, we are told, have never shown any sign of diminution, and this is the water that must be encountered in sinking a shaft. There are ten wells in operation at Goderich, the most important one to the present project being known as the Hawley Well, located at an elevation a few feet above Lake Huron at the mouth of the river Maitland, at a much lower level and nearer to the proposed shaft than any other well in the district. At this well the feeders

Jan 1, 1877

By John Henry Harden

IN 1874, with Mr. H. Y. Attrill, of Baltimore, Md., I made an examination of some property at Goderich with reference to sinking for and mining salt. With this end in view we visited all the wells in the neighborhood, but the information sought being of so unreliable a character I advised the putting down of a borehole on the property. This has since been done, the result of which has lately been published by Dr. T. Sterry Hunt in the Toronto Globe. From this there appears to have been passed through six beds of salt of an aggregate thickness of 125 feet. Rock-salt was known to exist, for, by the boring of existing wells, small crystals had been brought to the surface in the dirt, but no attempt had before been made to obtain a reliable sample or to prove the number and thickness of the beds. The question now remaining for discussion is, shall the present method of obtaining the salt be continued, or shall the beds be won by a shaft in a regular mining fashion, by which means the salt may be gotten in a condition almost ready for the market? The present mode of obtaining salt is by boreholes from 6 inches to 8 inches in diameter drilled to the beds, into which is inserted a pump. The "feeders" of fresh water intersected in drilling the well are allowed to descend on the outside of the pump-tube to the salt beds and there become saturated, when, on use of the pump, brine is obtained for evaporation. In the beginning brine can only be had in limited quantity, but by the daily application of the pump, and the gradual solution of the salt, a larger surface becomes exposed to the action of the fresh water, and a continuons supply of brine is obtained. It will then be understood that the supply of brine is dependent upon the feeders of fresh water intersected in boring the well, which, we are told, have never shown any sign of diminution, and this is the water that must be encountered in sinking a shaft. There are ten wells in operation at Goderich, the most important one to the present project being known as the Hawley Well, located at an elevation a few feet above Lake Huron at the mouth of the river Maitland, at, a much lower level and nearer to the proposed shaft than any other well in the district. At this well the feeders

By Richard A. Walker, John P. Hager

The thermodynamic properties of the Pb-Au system have been determined between 750" and 1075°C by means of the cell Mo, Pb(1) |(PbO-SiO2){l) , SiO2(s) |Pb-Au(1), Mo The activities of lead and gold exhibit negative deviations from ideal behavior; the values of ? pb and ? the raoultain activity coefficients at infinite dilution, being 0.24 and 0.25, respectively, at 1200°K. The liquidus curve for the gold-rich region of the Pb-Au phase diagram has been determined from measure-ments on seven alloy compositions in the two phase region (liquid + Au(s)). The standard free energies of formation of Au2O(l) and Ag2O (1) have been estimated from cell measurements obtained by replacing the alloy electrode with pure liquid gold and silver. A new integral molar heat of mixing curve for the liquid Pb-Au system is presented and the results of previous studies discussed. The contribution of HM to FE was found to be small relative to TSE. THE use of galvanic cells of the type A(l) |A+Za|A - B(l) [I] provides an accurate means for the thermodynamic study of liquid alloy systems. In Part 1&apos; it was shown that cells of type [I] may be extended to higher temperatures and to a wider range of alloy systems if the ion A+Za is incorporated in an appropriate molten oxide phase, rather than in the classical fused salt electrolyte. In the following investigation the experimental method is extended to an investigation of the thermo-dynamic properties of the Pb-Au system by use of the cell: Mo, Pb(l) | (PbO-SiO2)(l), SiO2(S) |Pb-Au(l), Mo [] Previous measurements on liquid Pb-Au alloys were obtained by Kleppa2 by electromotive force measurements on a galvanic cell involving a molten chloride electrolyte. These measurements were confined to temperatures less than 830°C and compositions with X Pb > 0.2 because of the instability of the cell at higher temperatures. Later measurements by Kleppa3 on the heats of formation in the composition range 0.67 < Xpb < 0.98 were not consistent with the results by electromotive force measurement. The purpose of the present study is to extend the temperature and composition range of the thermodynamic properties and to obtain an independent measure of the integral molar heat of mixing over the entire composition range.

Jan 1, 1970

By Larry Murphy, Mohammad R. Jafari, David M. Giel, Sharat K. Kalluri

"Built in 1940’s to provide a key roadway arterial between New York and Boston, the Heroes Tunnel is the only highway rock tunnel in the state of Connecticut and is part of the Wilbur Cross Parkway. This 365.0 m long tunnel consists of two barrels, each with two lanes of traffic, and carries over 71,000 vehicles per day. For nearly 70 years, the tunnel has seen millions of vehicles pass through but time has taken its toll and now the tunnel lining, ventilation system and radial section joints are significantly deteriorated and in need of rehabilitation. Owned and maintained by the Connecticut Department of Transportation (CTDOT), CTDOT initiated a unique managed approach to mitigate the risk, social impacts and financial implications associated with rehabilitation of this tunnel. This new approach consists of performing field inspection and conducting a comprehensive study to explore six rehabilitation options, including construction of new tunnels and enlarging the existing tunnels. The main criteria for this study are: Impact on traffic and the resulting delay cost; Construction cost; Construction duration; and Construction complexity. This paper will present the results of the alternative study. PROJECT BACKGROUND Location and Importance Heroes Tunnel is located in the State of Connecticut within the Town of Woodbridge and the City of New Haven near the Town of Hamden border. Heroes Tunnel is the only true highway tunnel in the State of Connecticut. The tunnel is part of the Wilbur Cross Parkway (Route 15), a scenic connection between Hartford and New York. Originally constructed and opened to traffic in 1949, the tunneled portion of the parkway passes through the West Rock Ridge. The tunnel was originally named West Rock Tunnel, but was re-designated as Heroes Tunnel in 2003. Route 15 is a vital roadway within the State transportation infrastructure. In the vicinity of Heroes Tunnel, Route 15 carries approximately 71,000 vehicles daily. Locally, Route 15 provides access to residences, shopping centers, and points of interest, as well as other state roadways. Regionally, Route 15 connects New York to the Hartford area and serves as an alternate expressway route to I-95 and I-91. The tunnel is approximately 365.0 m long and passes through the West Rock Ridge. West Rock Ridge is an 11.3 km long rock ridge located on the west side of New Haven. A network of suburban streets abuts the mountain on all sides and a seasonal paved park road climbs to the crest of the ridge. Figure 1 depicts the tunnel topography and location."

Jan 1, 2016