From these tables we can estimate the probable length of life of ties manufactured from any wood treated with chloride of zinc for any section of the country. Using this life as a basis the annual cost may be figured from the current prices for materials and labor at any time by the application of the following formula for economic comparison of cross ties of different materials, taken from page 64, 1915 edition of A.R.E.A. Manual:

A = Annual Cost-Amount at compound interest which will provide for renewal at end of life of tie.

n = Life of tie in years.

It will take but a few moments of time to determine just how much one can afford to pay for a tie to be treated with zinc chloride to secure the estimated life. To serve as a guide the following example has been prepared:

Example for comparing the annual cost of untreated white oak tie with zinc treated red oak; zinc creosote treated red oak and creosote treated red oak tie:

Creosote treated red oak tie:

Red oak tie, grade 3, cost..

Freight and handling

21⁄2 gallons creosote oil used at 12c per gallon..

Cost of treatment..

Insertion in track

Cost of tie in track.

Estimated life

Interest rate

.$0.90

0.50

0.30

0.19

0.40

$2.29

18 yrs.

Annual cost by application of formula

6%

.$0.21

The prices used for the example represent current prices in St. Louis territory as of November, 1921. Each individual railroad can substitute its current prices in making comparisons of real cost of ties in its respective territory.

Rainfall Regions:

It is generally agreed that zinc chloride will give the best results in regions in which excessive rainfall is absent, and zinc chloride should not be used to treat cross ties when they are to be used in regions of excessive rainfall or precipitation if it is possible to secure creosote.

The Committee calls attention to the line showing the division between the use of creosote and zinc chloride treatment for cross-ties in Bulletin No. 213 of January, 1919, page 150, where it was recommended that the territory north and west of the black line should be considered zinc chloride territory, and that south and east should be considered creosote territory.

In December, 1919, Bulletin No. 222, page 338, a revision of this map was published again showing "Proposed line showing the division between the use of creosote and zinc treatment for cross ties." On this map it was indicated that creosote oil should be used east of the revision line and zinc chloride west of the revision line.

Now that conditions have become more or less normal, it would appear desirable to more accurately define regions in which zinc chloride can economically be used for the treatment of cross ties. The reason for the drawing of the original map limiting the use of creosote and leaving the larger territory of the United States for use of zinc chloride was a specific war emergency due to the fact that only a very small amount of creosote was available. In other words, it was practically a line limiting the use of creosote. At the present time a line for limiting the use of creosote for tie treatment is evidently no longer necessary, because it is generally accepted that when it can be economically used creosote may be employed in any section of the United States.

A line, furthermore, does not correctly delineate regions where zinc chloride should be used. The choice between the two preservatives is after all one depending upon the risk taken in making an initial investment, meaning thereby the probable life which can be estimated for ties with either treatment. It is generally agreed that zinc chloride will give the best results in regions in which excessive rainfall is absent.

If any delineation is made it should be in terms of areas in the United States instead of whole regions as in the map published in 1919. This map is wrong, both for creosote and for zinc, and the recommendation is that it be withdrawn and a map prepared, if this can be done, showing in forms of shaded areas, regions where reasonable returns may be expected from ties treated with zinc chloride. Such shaded areas should, if possible, indicate in terms of length of life what may be reasonably expected from zinc treated ties laid in that territory.

The Committee was unable to complete such a map this year and suggests that this be made a subject for next year.

Recommendations:

The Committee recommends the use of zinc chloride as an economical investment.

Test Sections:

REASON FOR TEST SECTIONS:

(1) Life records-This will give a stimulus to longer life, of all ties and a general interest in the tie performance on the railroad.

(2) On the assumption that the test sections are representative of average conditions on the railroad, they indicate the tic performance on the divisions.

HOW TO MAKE A TEST SECTION :

(1) Select a section representative of average conditions on the
Division. This section should be selected by the Division
Staff.

(2) Test sections should be a Section Foreman's section.
(3) The general practice of the railroad in renewing ties should
be followed as distinguished from the practice of renewing
ties out of face.
(4) The ties when inserted should be marked with dating nails.
The psychological effect on the Foreman by the use of dating
nails on treated ties is usually underestimated. A dating
nail in a cross tie means to the Foreman that the tie in
question is expected to give longer service than the tie not
so marked, and he will do his utmost to conserve that tie.
It also serves as his record of the life of all treated ties in
his particular track and he will exert himself to the utmost
to prolong the life of such treated ties, especially when he
knows that the dating nails are a record and he will be
checked up on the service life given by the ties on his section
as compared with ties on adjacent sections.

Record of Test Section:

(1) One person should be responsible for all test sections (the necessary assistance to be employed to secure the proper record).

(2) This record should be kept by individual ties in each section in a book provided for that purpose.

(3) Annual inspection should be made and a report prepared of the results obtained to the end of the year, copy of this report to go to all Officials interested and the Section Foreman in charge of test sections.

(4)

(5)

All ties removed should be held until inspected by the
Official in charge of the test section.

Section Foremen should prepare a report each month of ties
inserted and removed. This should include kind of wood
treatment, date inserted, and reason for removal. This re-
port should go to the Official in charge of test sections.

The Committee recommends that test sections be established, and when established, the method to be followed be in accordance with recommendations herein.

Dating of All Ties:

It is the recommendation of the Committee that all ties inserted in the track should be marked with a dating nail, indicating the year in which they were inserted. This is the only means available for identifying the ties and determining just what service life is secured. This recommendation not concurred in by one member of the Sub-Committee.

The effect on the Foreman and the tendency to watch a dated tie with more care than an undated tie, is clearly brought out in paragraph (4) under heading of "How to Make a Test Section."

Extend test records to include treated timbers in bridges, docks and wharves:

Your Committee prepared a questionnaire to cover the practices in use of treated timbers in bridges, docks and wharves, which was forwarded to various railroads.

To date we have received replies from fifty-six railroads, thirty-one of which indicate that treated material is used to a considerable extent in bridges, docks and wharves, and its use is being extended each year. Some of the railroads were confining the use of treated material to piling, stringers and caps of their open deck trestles and to timbers in the floor system of ballasted deck bridges. Twenty-five of these railroads answered to the effect they had no experience as yet with treated timbers in such structures.

All railroads that have used treated timbers in their bridges, docks and wharves to any extent, speak very highly of the benefits they are receiving from such use.

On account of the meager information that was secured, it is not possible to prepare a report at this time that will show anything but progress. It is, therefore, suggested that the various railroads be requested to keep a record of the treated timbers in their bridges, docks and wharves, as is done in connection with their treated ties. If this record is started and continued it will furnish valuable information which will emphasize the importance and economy in the use of treated timber in these structures.