(X) SURFACE FINISH.-93. Revise second sentence to read-Care shall be taken to avoid an excess of mixing water in the concrete, and to drain off or to otherwise promptly remove any such excess water that comes to the surface after the concrete is deposited.

(XI) DESIGN.-On page 33-Section 105-D-Various ratios are given for the moduli of elasticity of steel and 28 day concrete, but frequently in railroad work it is found necessary to put loads upon structures inside of 28 days. What should the corresponding ratios be in such cases, that is, how will the age of the concrete affect the ratio, defined in paragraph 107 as "n"? It would be desirable to have the values of Sec. 105, etc., indicated by graphs where possible.

Section 115 would not seem to apply to a continuous width of floor of bridge supported at intervals by beams; in such a case what would be the unsupported length of flange? Isolated T-beams mentioned in Section 119, might have a portion or all of their length unsupported laterally, but I cannot conceive of an entire floor, supported by beams, which would be lacking in lateral support for these beams.

Page 58-following "J"-it would be desirable to have another article dealing with arches. Perhaps the Committee will cover this in a later edition.

Pages 61 to 64-Table 4 gives minute proportions expressed by volume; as the text indicates that proportioning by weight may be allowed, how are the figures given in table 4 to be of service in obtaining the correct proportions when the weight method is employed in proportioning?

The Joint Committee is to be highly commended for establishing the standard notation given in Appendix 1-page 65, etc., as much confusion in the future will thereby be avoided.

A. F. Ganier, Assistant Engineer Design, Nashville, Chattanooga & St. Louis Railway

No. 7-Stone screenings is included among the materials for the fine aggregate. The results we have had hereabouts with certain grades of limestone are such that I think the specification should eliminate limestones which will not stand the weather.

No. 79 Eliminates the use of integral water-proofing compounds. This is a rather sweeping decision, and I can find no reason for such elimination in the literature I have read. A small amount of hydrated lime (10 per cent.) has been shown by competent authorities to actually increase the strength of concrete, aside from its quality of rendering it more water-proof. The membrane method recommended is too expensive for many classes of work.

No. 82. I think that the reference to the "surface coating" should be amplified to say that "this coating shall be such that it will enter and fill the pores, thus reducing the porosity of the concrete."

No. 95-The second paragraph of this section does not clearly provide for the removal, from the surface, of all dust and other foreign matter which would affect the bond.

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 a 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 (11⁄2 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 11⁄2 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 11⁄2 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 preparing specifications to fit local conditions.

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.

A

(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. Signal 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.

(c) Results obtained from oiling track fixtures.

(d)

The use of guard rails on curves, considering specifications
to cover conditions, as: degree of curvature; speed; traf-
fic conditions; grade.

Respectfully submitted,

THE COMMITTEE ON TRACK,

W. P. WILTSEE, Chairman.