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(b) Repaving Repaving with better material (asphalt, wood, stone-I or III classes, etc.) in as far as it is not included in the reconstruction of streets and intersections previously noted was as follows:

1907
1908
1909
1910

1911 $366,461.52 $269,610.00 $178,206.72 $194,394.72 $97,361.04 These expenditures are offset by the following receipts:

1907
1908
1909
1910

1911 1. For old material, etc...

$49,717.44 $63,407.28 $29,049.12 $34,079.52 $14,417.26 2. Contributions of

street railroads... $10,455.60 $9,395.28 $258.60 $7,491.84 $1,505.04

The length of streets repaved in 1911, the area resurfaced and the class of material are noted in the following tables:

Expenditures for the maintenance of street pavements, including the relaying, principally with old material and including the costs for street railroad work in the budgetary year are:

1907
1908
1909
1910

1911 $396,990.56 $430,264.08 $442,286.88 $465,894.72 $239,020.80 These expenditures are offset by the following receipts for old material, etc.:

1907
1908
1909
1910

1911
$5,360.40 $1,957.20 $10,380.48 $5,831.28 $2,346.00

CITY DEPARTMENT OF WORKS—CHARLOTTENBURG SPECIAL SPECIFICATIONS FOR THE CONSTRUCTION OF COMPRESSED ASPHALT PAVEMENT ON

CONCRETE FOUNDATION, FISCAL YEAR 1912 § 1. Object of the Specification.--The object of these specifications is the construction of compressed asphalt pavement in several streets of Charlottenburg designated by the Administration, as well as all other work, deliveries, etc., in connection with it, which may be required of the contractor. The contractor has no right to claim a definite amount of the contract.

These specifications, as well as the proposal, are binding in streets having no rail tracks, and also in streets where tracks are newly laid or changed in conjunction with the paving, providing the asphalt work within the railroad area is done by the Administration, In the latter case all work incidental to the construction of the tracks at the right height is to be done by the Administration, but all earth work, leveling and paving are to be done by the contractor.

On account of the heavy traffic of pedestrians, wagons, tramways and automobiles, special attention is called to $ 13, clause 9, of these specifications, according to which the contractor has to provide for the safety and convenence of the public, also for the guarding of streets at night at his own expense.

§ 2. Scraping and Leveling of the Ground, Carting off of Superfluous Soil and the Delivery of Soil Needed for Construction.—The scraping and distributing, also the carting away of superfluous soil and the delivery of soil needed for construction, are to be done by the contractor, according to Arts. 1-4 of the proposal. An estimate as to the quantity required will be given by the Administration, the accuracy of which shall be tested and approved by the contractor. The soil which may be required must be a good quality sandy soil, free from loam. In leveling the road-bed, the soil is not to be disturbed below the level of the top of the foundation. The use of picks is therefore not allowed if the depth of soil to be taken off is less than eight inches. Picks are to be used only with permission of the engineer. In case the road-bed does not consist of good packed soil, the contractor has to put the bed in such condition through flushing, ramming or rolling, so as not to allow any sinking of the road. The water and hose necessary are to be furnished by the city free of charge; but all labor has to be furnished by the contractor. If the packing of the road is effected by the contractor, he has to stand the cost of the labor and draught of the roller. In all other cases the expense is defrayed by the Administration. Should any sagging of the road occur, due to faulty con. struction within the guarantee time, the contractor has to repair or make good any loss at his own expense.

It is the contractor's duty to inform himself of the condition of the roadbed before starting any work.

Should any pipes, cables, masonry, roots of growing trees, etc., become exposed during the leveling of the road-bed, due notice has to be sent to the Administration in charge of the upkeep of the conduits, trees, etc. The contractor has to carry out all orders from the Administration in regard to these exposed objects and has to make all removals or changes at his expense. He is also responsible for all damage done to trees, conduits, etc., during the construction. Exposed roots have to be covered with wet bags. In no case shall materials be stored on trees or within the protective structures about trees.

83. Road-bed Construction.—All points determining the surface of the roadbed shall be given. The base of the concrete foundation shall be marked at every change of grade with a sufficient number of stakes. It is the contractor's duty to see that those stakes are not removed through accident or carelessness. Should a stake have been removed, the contractor has to stop all leveling up to the next stake until new marks are set by the Administration. All cost of extra work in this connection has to be defrayed by the contractor.

The bed for the concrete foundation is to be constructed according to the stakes and has to correspond to the surface of the street. The normal profiles for the cross grade of the streets are in the hands of the Administration. It is the duty of the contractor to prepare the plans according to these profiles and submit them for approval to the Administration.

§ 4. Construction of Concrete Foundation.—The road-bed has to be prepared according to specifications to a length of at least 65 feet before any concrete work is to be started.

The road-bed has to correspond to the plans. Particular care has to be taken that the surface is free from all irregularities, elevations as well as depressions. The concrete work is not to be started until the road-bed is accepted by the Administration.

a.

Delivering, Moving and Storing Construction Material. All construction material is to be delivered by the contractor. For storing the material the adjoining streets and places are to be used, providing the police and the Administration do not object. If permission is granted to store the material on the finished subgrade, the moving of the material shall be done in hand-carts and on planks. Gravel shall be stored on a platform, if stored on the subgrade, to prevent any contamination by soil.

A small quantity of material shall be kept at the store places if desired by the Administration.

In storing material in adjoining streets, the contractor has to take care not to obstruct traffic. Wagons are not to be loaded in the part of the street open to traffic.

b. Thickness and Preparation of the Concrete The usual thickness of the concrete shall be 8 inches, providing no other thickness is specified, as in the construction of streets with railway tracks. Under no condition shall the thickness be less than 12 inch.

The concrete shall be a mixture of cement and gravel. In the mixing of the

concrete one barrel of cement, the normal weight of which shall be 396 lbs. gross or 375 lbs, net, shall be used for every cubic meter of gravel to make a mixture of about 1 part of cement to 8 parts of gravel. The weight of the filled cement barrels has to be established at the contractor's expense as often as desired by the Administration. Should, by exception, a larger proportion of cement be ordered by the Administration, in order to insure a quicker setting of the concrete, a corresponding compensation will be granted.

A measuring box of 17.65 cubic feet or 35.3 cubic feet shall be used for measuring the gravel to insure a mixture to conform to the specification. The mixing shall be done on a wooden platform, which has to be at least 12 inches longer on all sides than the measuring box. The long sides of the platform have to be provided with protecting borders to prevent the loss of any material. At least three platforms have to be erected at every construction place to insure the greatest progress in the work. The cement and gravel are mixed twice before any water is added. After the addition of water, the mass is mixed again until a stiff, but not fluid, paste is obtained. All foreign substances are to be picked out and removed from the concrete during the mixing. Concrete, gravel or cement which, during the mixing, drops from the platform, is not to be picked up and used in the foundation, but has to be removed. Any infraction of this rule or the laying of concrete to a depth less than that required will make the contractor liable to a fine of 20 marks in every instance, which shall be deducted from the final payment or from the contractor's security.

C. Construction of the Concrete Foundation To insure the proper construction of the concrete foundation, guide-strips of the proper thickness, 8 inches wide and parallel to the street, are to be laid in the plane at intervals of 13 to 16 feet. The greatest care in regard to proper thickness and position has to be taken in constructing the guide strips. Faulty guide strips are to be removed at once. The concrete shall then be spread upon the subgrade and rammed or tamped to fill all voids and bring the surface to the exact height of the guide strips.

The concrete shall be sprinkled with water or covered with wet covers during the setting, so as always to have a moist surface. It shall also be protected with planks as long as it is too soft to walk upon.

Concrete is not to be laid at temperatures below 2.5 degrees C. Should frost set in after the laying of concrete, it shall be protected with straw, blankets or matting for at least three days. The water, also the coverings in case of frost, are to be furnished by the contractor.

The necessary water may be taken from the nearest hydrant. 2.2 cubic feet of water are estimated for 1.2 square yards of concrete and the price of 35.3 cubic feet of water shall be $0.02. The price for the water shall be deducted from the final payment.

d. Concreting in Connection with the Construction of Railroads

and the Changing of Tracks Should the construction of railroad tracks be connected with the paving, the concrete for the railroad area shall be laid first, according to sketch below. The 26-inch wide strip outside of the tracks shall be the gauge.

The top surface of the concrete below the tracks has to be cleaned of any cement slime and has to be roughened. The laying, connecting and leveling of the rails are to be done by the railroad company. After completion of a certain distance, the joints between the concrete and the under surface of the rail shall be filled with either:

a mixture of resinous or bituminous substances, or
b. a cement mortar of 1 part cement to 1 to 2 parts of sharp sand.

a.

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In case double rails are laid, the space between must be filled water-tight up to about 1 inch below the upper surface of the rail with either:

c. pearl sand which has to be covered with a resinous or bituminous

substance, or d. a mixture of 1 part cement and 2 parts sharp sand or gravel. As it is impossible to use cement in frosty weather or bituminous material in wet weather, it is advisable to use, in the former case, the mixture described under "a" and "c" and, in the latter, that under "b" and "d.”

The construction of the concrete up to the right height is started as soon as the rails are thoroughly fastened.

e.

Concreting for Pavement Connections Besides all extra work ordered by the Administration in connection with the pavements, the contractor shall construct a concrete foundation for the connection at street with stone pavement. This concrete shall be 8 inches thick, about 344 feet long and shall extend over the whole breadth of the street, and shall be laid at the same time as the concrete of the street to be paved.

8 5. Quality of the Materials to Be Delivered hy the Contractor.—The gravel to be used for concrete must be free from soil, loam, marl and vegetable matter. The individual grains shall consist of clean quartz and shall not be mixed with soft and weather-beaten stones, as.chalk, slate, shale and coal particles.

For the determination of the quality of the material, the following method shall be used.

The material is dried to constant weight and is sifted, after all lumps are carefully crushed, through four sieves with meshes of .008, .024, .08 and .28 of an inch. The sieves are numbered from 1 to 4, starting with the finest. The sifting is started on sieve No. 4 and is ended on sieve No. 1, in such a way that all sand passing one sieve is treated further on the next sieve.

The gravel passing sieve No. 1 shall be termed grain size 1
That retained on sieve No. 1 shall be termed grain size 2
That retained on sieve No. 2 shall be termed grain size 3
That retained on sieve No. 3 shall be termed grain size 4

That retained on sieve No. 4 shall be termed grain size 5 The amount of the different sizes shall be expressed as % of the total weight of the sample by weight.

In regard to the composition of the gravel, the following is required: at least 50% of the gravel shall be composed of sizes 4 and 5 and the gravel shall contain all sizes. The amount of sizes 1, 2, 3, 4 and 5 shall be in the ratio of 1:2 : 3: 4: 4. Stones larger than 14 of an inch are to be rejected.

Gravel contaminated by soil or other foreign matter shall not be used and must be removed from the place of construction.

The contractor has to specify the brand of cement before the contract is awarded.

The brands of cement to be used are:

The cement of the above firms has to comply with the following specifications:

The cement shall be slow-setting and shall be a powder of such fineness that not more than 4% shall be retained on a sieve having 76 meshes per inch and not more than 25% on a sieve having 180 meshes per inch. At least 99.5% of the cement must be soluble in dilute hydrochloric acid. The content of sulphuric anhydride in calcined cement shall be not more than 2.5%. A mortar made of 1 part cement and 3 parts of standard sand kept 1 day in damp air, 6 days in water and 21 days in air at a temperature of 15-30 degrees C. shall have a crushing strength of at least 3902 lbs. per square inch; and if kept 1 day in damp air and 2 days in water, a crushing strength of at least 3122 lbs. per square inch. In all other respects the cement has to conform to standard methods of testing and specifications for cement of the Society of German Portland Cement Manufacturers.

A sample of cement or concrete shall be taken from the place of construction as often as the Administration so desires.

$ 6. Samples of the Construction Materials; Statement of Sources.-A sample of the gravel to be used is to be submitted at the time the bid is made. The construction materials have to correspond to all samples. The question sheet given to the contractor has to be filled out and returned to the Administration. Samples of the asphalt rocks, asphalt powder, bitumen and cements are to be submitted

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