99. Inspection.—The lumber for paving blocks will be inspected before it is cut into blocks. The blocks will also be inspected upon delivery to the street and as they are laid. Blocks that have, in treatment or subsequent handling, developed open season cracks or wind shakes or other imperfections that may prevent their durability or usefulness in the pavement shall be rejected and removed from the street.
100. Chamfered Blocks.—Where wood-block pavement is laid on streets or parts of streets having a gradient of more than 3%, the blocks shall not be less than four (4) inches long, and the upper side-corners of the blocks shall be chamfered to a depth of three-eighths (⅜) inch, the chamfered surface to make an angle of 40 degrees with the vertical sides of the blocks; or such other construction shall be used as will, in the opinion of the Engineer, provide an equally good foot-hold for horses.
101. Expansion Joints.—Before the blocks are set there shall be placed along and against each curb a board of trapezoidal section having a width one inch greater than the depth of the blocks, the upper edge of which shall have a thickness of three-eighths (⅜) inch for each ten feet or fraction thereof of the width of the street between curbs, and a bottom width one-fourth (¼) inch less than the top. The paving blocks at the beginning and end of each course shall be set against this board. After the ramming of the blocks has been completed, these boards shall be carefully withdrawn and the space between the curbs and the paving blocks shall be completely filled with the bituminous paving cement described in Section 90.
102. The street shall not be opened to travel until such time as the mortar under the blocks shall have become well set, nor until the Engineer shall so direct.
BITUMINOUS CONCRETE PAVEMENT
Note.—The phrase, Bituminous Concrete Pavement, has been applied to a large variety of roadway surfaces differing materially from each other in composition, construction and utility. Some of these are covered by United States patents, the scope and limitations of which are not yet fully determined or understood. The necessity of avoiding infringement of these patents has to be kept in mind in framing specifications for public use, and this consideration does not permit the presentation here of specifications which, in the opinion of the author, would secure an ideal pavement of this general character.
Bituminous concrete pavements constructed in substantial conformity with these specifications have been laid on a number of city and town streets and country roads and have proved satisfactory and fairly durable in use. It is believed that they do not infringe any existing patents.
Our rather limited experience with pavements of this character seems to indicate that if good materials are used and the work properly done, they are suitable for use on city streets of light travel, and on suburban streets and country roads carrying an amount of travel considered heavy for these classes of roadways. Where the results have been unsatisfactory, the cause can generally be traced to unsuitable materials or unskillful construction, the result of ignorance or carelessness on the one hand, or of the attempt to reduce first cost below normal figures on the other. Many people are searching for a pavement or roadway that will have all the good qualities of the standard pavements but can be built about as cheaply as a common macadam road. It is possible that something of the kind may be discovered; but in the present state of the art it is chimerical. High quality and low first cost do not go together in street paving. The question to be considered is, rather, how can we invest a dollar in street or road building so that it will, in the long run, yield the best return upon the investment. The pavement provided for in these specifications is not a cheap pavement, but where it is suitable for the conditions to be met, it will be well worth its cost.
SPECIFICATIONS
103. Sub-grade.—The sub-grade except where old pavement is utilized for foundation shall be prepared in accordance with Section 26 of these general specifications.