To the Members of the American Railway Engineering Association: 1912. Two meetings were held during the year as follows: At New York on May 13, 1912, at which were present Messrs. George W. Kittredge, Chairman; J. B. Austin, Jr., Vice-Chairman; D. J. Brumley, R. D Coombs, G. A. Harwood, A. B. Hill (representing Mr. Geo. Gibbs), E. B. Katte, Martin Schreiber. At New York on February 10, 1913, at which were present Messrs. George W. Kittredge, Chairman; J. B. Austin, Jr., Vice-Chairman; R. D. Coombs, E. B. Katte, C. E. Lindsay, Martin Schreiber, W. I. Trench. The balance of the work of the Committee has been done by subcommittee meetings and by correspondence. (1) CLEARANCES. Your Committee submits the following report as one of progress and information: This Committee has considered a communication calling attention to interference with the bridge clearance line of the Association by the recently adopted third rail, permanent way structures and rolling equipment clearance lines, and has made a recommendation to the Committee on Iron and Steel Structures that as much of the bridge clearance diagram as interferes with the third rail and permanent way structures clearance line be eliminated, and in place thereof the clearance line for permanent way structures be substituted on roads where electric equipment is likely to be used. The Committee on heavy electric traction of the American Electric Railway Association submitted a report at the annual meeting held at Chicago in October, 1912, which report recommended clearance lines for third rail, permanent way structures and rolling equipment identical with the lines adopted by this Association at its last meeting, and also submitted for information and guidance a suggested clearance diagram for automatic stops, with the recommendation that the matter be continued to allow the Committee time to confer with similar committees of this Association and the American Railway Association. The American Rail way Association at its meeting in May, 1912, adopted a clearance diagram for third rail, permanent way structures and rolling equipment identical with the diagram adopted by this Association. The Committee has been following up the progress made during the year on third rail installation and has had the table which accompanied last year's report brought up to date and same is resubmitted as information. It is urged on the members of this Association that they try and induce their Companies to conform to the clearance diagram on all new work and gradually change over their present installation so that ultimately there can be a free interchange of electric equipment between the various roads. The Committee has been collecting during the year data in regard to overhead clearances and is studying same with a view of taking up this question during the coming year with committees of the American Electric Railway Association and the American Railway Association, so that joint recommendations for overhead clearance lines may be made by the respective committees of each Association. The Committee is not prepared at this time to take up the question of clearance lines for automatic stops, but as soon as a device that is adapted to conditions obtaining on roads operated in the open has been perfected, the question of established clearance lines will be further considered. (2) TRANSMISSION LINES AND CROSSINGS. Your Committee desires to report progress on the consideration of modifications of the specifications for overhead crossings of electric light and power lines adopted by the Association at the last convention for Transmission Lines and Crossings as will be necessary to cover voltages over 70,000 and also the consideration of the revision of the specifications in paragraphs Nos. 10, 13, 18, 24, 29, 31, 32, 34, 45, 49, 51, 55, 60 and 61, which were adopted by the Association with the understanding that the revision of these particular paragraphs would be considered this year. Your Committee, however, is not prepared at this time to make any further recommendations for the reason that more time is required to study the development of the art in respect to voltages over 70,000 and further because of the fact that all of the various similar associations have not yet modified theirs or formally adopted ours so as to make uniform specifications. We know of no reason, however, why those tha: have not should not do so as opportunity for revision comes up. In other words, our specifications are not objectionable. (3) ELECTROLYSIS. An invitation has been received from the American Electric Railway Association to unite with them in jointly considering the subject of "Electrolysis," and your Chairman has appointed Messrs. Katte, Gibbs and Brumley to serve on this Joint Committee with Messrs. Townley, Richey and Palmer, the members appointed by the American Electric Railway Association. Your Committee submits the following report with recommendations that it be printed in the Proceedings of the Association as information. Introduction. The effect of electrolysis upon steel and iron structures, including water, gas and electric conduit pipes, also on the lead sheaths of insulated cables, has been a matter of serious concern ever since the first street car was operated electrically by means of a grounded return, but not until the advent of electrification on steam railroads did the subject become one of much interest to railway engineers. The matter is receiving the careful consideration of electrical engineers in conference with structural engineers and representatives of various municipal departments, but up to the present time there is no unanimity of opinion as to the best methods of preventing electrolysis, or for protecting metal structures adjacent to the path of grounded return circuits. For this reason your Committee cannot recommend any standards or preferred practice, but have compiled for your information a statement of methods pursued and a description of the research work now under way at some of the more important localities of particular interest to railway engineers. The descriptions have been prepared to cover locations as follows: Brooklyn Bridge, Borough of Brooklyn Traction System, Grand Central Terminal, New York City; Pennsylvania Terminal, New York City; City of Chicago Traction System; Bergen Tunnels of Delaware, Lackawanna & Western Railroad; Baltimore & Ohio Railroad Terminal, Baltimore, Md. In addition to this brief description of actual conditions there has been prepared a short explanation of the phenomenon of electrolysis and the more common methods of preventing its action; also a list of reference books and papers dealing with the electrolytic problem is appended to this report. NATURE OF ELECTROLYSIS. Electrolysis as referred to in the Electric Railway discussions may be described as the wasting away or corrosion of a metal which is caused by an electric current passing from one metallic conductor to another conductor where both are buried in damp earth, or other semi-conducting medium. CAUSES AND EFFECT OF ELECTROLYSIS. In direct current railway circuits the electric current passes from the power station or substation to the trolley wire or third rail, then through the motors of electric cars or locomotives and back to the station by the track rails. Owing, however, to the fact that it is practically impossible at all times to insulate the rails adjacent to the ground, part of the current leaks into the earth and finds its way back to the station through the ground, and in doing so, if pipes, cable sheaths or steel work are under or adjacent and parallel to the tracks, some of it may return by these metallic structures. At some point or points this current must leave these metallic structures and usually does through the earth in the neighborhood of the power station or substation, causing electrolytic effects in the underground structure or conductor at the points in question, unless precautions have been taken, as later indicated. There is less opportunity for current to escape from the tracks on electrified roads where the rails are above ground and rest on wooden ties in ballast and there is no opportunity for such escape where the return circuit does not enter the running rails but is conducted back to the power station by independent and insulated contact rails or wires. Examples of this method of construction are found in slot conduit street railways and those having double overhead trolleys; also in those using a separate insulated return conductor rail. It is common practice to connect the negative bus-bars in the power station or substations with the running rails by copper cables at the points nearest to the stations. Such a connection is shown in Fig. 1. Leakage of current from the rails to the adjacent water pipes along the line may thus occur and the current flowing in these pipes leaves them and returns to the rails in the neighborhood of the power station, causing electrolysis at the points where it passes from the pipes through the earth. PREVENTION OF ELECTROLYSIS. It is possible to prevent electrolysis by precluding the escape of electric current from the return conductors, but frequently this is not practicably possible as in the case of buried rails carrying return current. Several methods of meeting this latter condition have been employed, briefly described as follows: (a) Drainage System.-In order to prevent this escape of current into the earth, negative cables are sometimes run from the power station or substation to adjacent pipes or metal work so that the current will leave these structures through metallic paths, thus preventing electrolysis at such points. This system is successfully used in connection with continuous cable sheaths or pipe lines having screw joints, although it results in inducing a larger volume of flow by these paths. It is objectionable, however, in water pipe lines having lead joints, as frequently electrolysis is induced at the pipe joints as shown in Fig. 2. This method of reducing electrolysis is known as the Drainage System. (b) Insulated Negative System.-Another system employed is to provide insulated cables which are connected to the rails at points remote from the station. This style of connection is shown in Fig. 3. It is largely employed in Europe and is beginning to be specified in connection with the American systems. This has the effect of maintaining a more uniform and lower negative potential and largely prevents the current from leaving the bonded rails. The objection to this system |