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Page No. 32–That portion of the pamphlet dealing with the mathematical design has been arranged even more clearly than heretofore and fuller discussion than formerly has been given relative to the use of the formulae. With the small amount of time available I do not feel competent to take issue as to the use, or rather choice, of certain formulae which are recommended in the report.
The method of giving working stresses in concrete is such that great latitude is allowed, i.e., concrete having an ultimate compressive strength of 1,500 to 3,000 lb. per sq. in. is allowed a working stress of 0.4 f'c or from 600 to 1,200 lb. per sq. in. In competitive work there has been a strong tendency to stretch and even go beyond all recommendations. The stresses allowed are all right provided the Committee's recommendations as to proportions, choice of aggregates and methods of mixing are also carried out. This is rarely complied with, in this section at least, and the actual concrete put into the job is too often of the particular brand preferred by the foreman. I think the report should lay more stress on the necessity of field practice, conforming to its recommendations, and that engineering inspection should be counted in and recognized as proper element of the cost of good concrete. C. L. Wilson, Assistant Engineer, Bridge, Nashville, Chattanooga &
St. Louis Railway On page 19, paragraph 27, last sentence, and on page 81, paragraph 30, regarding the water measuring devices. I have never seen a contractor's equipment, that has been in service for any length of time and that carries such devices, to be in working order. Good concrete has been made by men experienced in mixing without an automatic water measuring device. At the same time, I realize that a certain amount of water added to the different mixes gives the maximum strength for that mix. For this reason the amount of water added should be measured as accurately as possible. This can be done by buckets, if the amount is previously determined by the engineer in charge.
Page 21, paragraphs 31 and 32, regarding time of mixing. It is true, that in hand mixing the batch is usually turned six times after the water is added. If this is necessary, then the time (1%2 minutes) required for machine mixing, after all material is in the machine, is longer than necessary and the yardage guaranteed by the manufacturer cannot be made in some makes of machines.
Different types and sizes of mixers require different times to make a homogeneous batch and an experienced man at the machine can tell when the mixing is complete.
I believe paragraph 31 should be revised, leaving out the time element, and reading the same as the last sentence of paragraph 32.
On page 26, paragraph 63. Plans usually show the position of splices. Rods are ordered and called for to allow the proper lap to develop the bond. Position of other splices that become necessary on account of construction features should be decided by the engineer in charge. The first sentence to be left unchanged.
Page 28, paragraph 79. This paragraph precludes the use of hydrated lime and coloring pigments, while paragraph 104, page 32, allows the use of colored pigments.
The results obtained from the added lime can be secured by the addition of a small percentage of cement and a careful grading of the aggregate. C. H. Johnson, Assistant Engineer, Nashville, Chattanooga & St.
Louis Railway The specifications cover not only the construction of concrete structures, but also their design, and I think it would be well to separate the specifications into two parts: one covering construction and the other covering design, instead of attempting to cover both in one set of specifications. As an example, I call your attention to page 26, where clauses 60, 61 and a part of 62 are applicable to construction, whereas, the latter part of 62, all of 63 and 64 refer to design only.
The clauses under the head of “Mixing” on page 21 are too stringent. It is entirely possible to secure first-class concrete with mixer using no charging hopper, no water measuring device or no locking device. In fact it has been my experience that charging hopper and water measuring devices are a nuisance and I avoid their use wherever possible.
The specifications requiring concrete to be turned in the mixer 14 minutes after the mixer is completely charged should be revised to read "Concrete shall be turned in the mixer a sufficient length of time to produce a batch that is homogeneous in appearance and color." This time will vary greatly with different types of mixers. We have one mixer where the material has to be turned one minute and a half or two minutes. We have another mixer where as good or better concrete may be made in three-fourths of a minute.
I note that in mixing by hand the specifications require that the material shall be turned at least six times after water is added. This is entirely inconsistent with the clause providing for holding material in the mixer 172 minutes.
On page 28, under "Waterproofing," clause 79, "Integral compounds shall not be used.” This would seem to exclude the use of hydrated lime, which we have found to be very satisfactory.
Page 29, under “Oilproofing," clause 82, closes with the sentence "The treatment to be applied shall be approved by the engineer." I believe a treatment, or some treatment, should be recommended by the Committee since these specifications are to be used as a guide to engineers in pre paring specifications to fit local conditions.
W. P. WILTSEE, Chairman; J. V. NEUBERT, Vice-Chairman;
H. A. LLOYD,
J. DEN. MACOMB, J. B. BAKER,
W. S. McFETRIDGE, R. A. BALDWIN,
F. H. MCGUIGAN, JR., C. W. BREED,
J. B. MYERS, G. H. BREMNER,
F. L. NICHOLSON, H. G. CLARK,
J. H. REINHOLDT, E. A. HADLEY,
G. J. SLIBECK, G. W. HEGEL,
J. B. STRONG, E. T. Howson,
J. R. WATT, T. T. IRVING,
Committee. To the American Railway Engineering Association: Report is respectfully submitted on the following subjects:
(1) Revision of Manual Proposed changes in the Manual, Items I, II and III, are given in Appendix A. (2) Typical Plans of Turnouts, Crossovers, Slip Switches, Double Crossovers and Railroad Crossings, and Detail
Plans for Such Work In Appendix B the Committee reports on this subject, and its recommendations are given under Conclusions.
(3) Plans and Specifications for Track Tools In Appendix C the Committee reports on this subject, and its recommendations are given under Conclusions. (4) Specifications and Piece Work Schedules for Contracting
Maintenance Work In Appendix D the Committee submits “Specifications and Unit Track Work Schedules for Contracting Maintenance Work," and its recommendations are given under Conclusions. (5) Plans and Specifications for Switch Stands, Switch Lamps
and Switch Locks In Appendix E the Committee reports on this subject, and its recommendations are given under Conclusions.
(6) Gages and Flangeways for Curved Crossings In Appendix F the Committee submits an explanatory report on Tables No. 1 and No. 2 recommended for adoption and publication in the Manual (Appendix A, Item III). (7) (a) Tests of Tie Plates Subject to Brine Drippings; (b) the
Effect of Brine Drippings on Track Appliances In Appendix G the Committee submits a progress report on this subject.
(8) Reduction of Taper of Tread of Wheel to 1 in 38, and Canting
the Rail Inward In Appendix H the Committee submits a progress report.
(9) Outline of Work for the Ensuing Year The Committee's recommendations are given under Recommendations for Future Work.
CONCLUSIONS 1. The Committee recommends that the additions to the Manual as submitted in Appendix A be approved.
2. The Committee recommends certain plans for adoption and others to be received as information. Appendix B also covers progress report on uncompleted work, and reassignment of the subject is requested.
3. The Committee recommends that the plans submitted be adopted and that the subject be reassigned, that the preparation of specifications which could not be completed may be continued.
4. The Committee recommends that the specifications submitted be adopted, and the Committee be authorized to continue its work on this topic.
5. The Committee recommends one plan for adoption and another to be received as information, and submits a list of certain A.R.A. Sig. nal Section plans, which it recommends for endorsement by the Association, and a progress report to be received as information. The Committee recommends that this subject be continued.
6. The tables submitted in Appendix A, Item III, and explanatory report in Appendix F completes the work of this Sub-Committee. The Committee recommends that this subject be discontinued.
7. The Committee recommends that the progress report in Appendix G be received as information and that the subject be reassigned.
8. The Committee recommends that the progress report in Appendix H be accepted as information and that the subject be continued.
Recommendations for Future Work 9. With the exception of Subject No. 6, the Committee recommends that the present assignments be continued, and, in addition, the following new subjects: (a) Method to be used in determining recommendations for
rail renewals. (b) Curving of rails. recommending limits of curvature to
spring in track for various weights of rails, etc.
to cover conditions, as : degree of curvature; speed; traf-
THE COMMITTEE ON TRACK,
W. P. WILTSEE, Chairman.
(1) STUDY THE MANUAL AND SUBMIT PROPOSED
W. P. WILTSEE, Chairman;
G. W. HEGEL, J. V. NEUBERT,
E. T. Howson, V. ANGERER,
T. T. IRVING, G. H. BREMNER,
J. DEN. MACOMB, E. A. HADLEY,
Sub-Committee. Item I
The Committee recommends the following Supplement to the Specie fications for Switches, Frogs, Crossings and Guard Rails, adopted March, 1921:
SUPPLEMENT TO SPECIFICATIONS FOR SWITCHES, FROGS,
CROSSINGS AND GUARD RAILS Manganese Steel Track Castings
1. GENERAL CONDITIONS.-Castings shall be reasonably smooth and true to pattern in accordance with good foundry practice. Large lumps, sharp fins, sand and chills on the outside of castings shall be removed. The castings shall be free from such blow holes, sand holes, cracks, cold shuts and other defects which would impair their serviceability and as further specified below. Castings must be out of twist and reasonably true, both as to general surface and alinement, and must not show any signs of straining or undue denting produced in the straightening process.
The bottom part of castings which rest on ties shall be reasonably straight and out of twist, and shall be free from lumps or such imperfections as would prevent a good bearing.
2. IMPERFECTIONS.--Tread surfaces within 21/2 in. of gage line and side of groove 1 in. down from tread shall be free from physical defects, such as shrinkage cracks, sand holes, blow holes, cold shuts or segregation of metal, unless such defects are so small that they have been practically removed by the finish grinding, and there must be no indication of unsoundness of the metal. Shrinkage cracks, cold shuts or segregation of metal will not be allowed in any part of the tread surfaces. Sand holes, blow holes, and cold shuts in portions of the casting where they will not appreciably weaken the casting, or impair its wearing qualities, will be permitted. Castings must be free from shrinkage cracks running vertically in web members of solid work or horizontally at or near the ends or in corners of junction of projecting members or longitudinally in grooves. Other small shrinkage cracks which do not materially weaken the casting will be acceptable.
The above Supplement, it is felt, would be of material assistance to the inspector on this class of work.
The Committee recommends that plan No. 252, dated November, 1921, and titled “Details of Lamp Tips for Switch Stands,” be adopted, and that Section 12 of "Requisites for Switch Stands, Including Con