Sanitation of Mofussil Bazaars :: CHAPTER III. Road Making.

CHAPTER III. Road Making.

One of the most important points towards obtaining a good metalled road is to ensure a proper foundation for the metal to be consolidated on, and to see that the sides are well confined or tied in. Where bricks are used for this foundation they should be whole ones, not bats, be tightly packed together and then rammed with a wooden rammer. The edging should consist of bricks-on-end well backed up with earth on the out, or berm side. The same applies where stone is used for the soling. These must have flat surfaces, be of fair size, and be well hand-packed together and rammed. It is not much use doing metalling work on a raised road until the embankment has at least 2 rains over it to properly consolidate it. This equally applies to the approaches to bridges on a kutcha road where the metalled portion should be extended to a length of at least 10 feet beyond the toe of the approach slope.

Stone Metal.

In most municipalities it is financially impossible to thoroughly repair all the roads each year, nor is it necessary to do so, if the work has been properly done. A system of biennial or triennial repairs should therefore be evolved. A diagram showing how this can be arranged is shown in Fig. 11, page 19.

In the selection of stone metal it is of great importance to see that stone of equal grade and hardness is used, and that surface, or weathered rock, is not mixed up with the harder material lying underneath it in the quarries. The stone should be broken to the size that the largest piece shall pass freely through a 1½ diameter ring. When repairing existing metalled roads it is essential that all old metal be picked up, and any rounded, or traffic-worn portions re-broken, as it is impossible to ensure good consolidation unless the edges and corners of the stone metal be sharp. Consolidation should be done by a heavy roller. A steam roller for preference. The cost of a 6–ton steam roller is about Rs. 6,000 and the working cost about Rs. 4 per day, but this must necessarily vary considerably in different localities, depending on the cost of fuel and labour.

Diagram
FIG. 11.

For Oiling Roads.

Oiling Roads.

The roadway must first be swept clear of dust and foreign material, when the mixture composed of one part of coal-tar to 20 parts of oil (liquid fuel), mixed cold, must be sprinkled on through a watering cart. Men with hard long handled brushes follow the cart, and brush the mixture into the roadway, and repeat this operation for the second time in the reverse direction, when ¼ of a mile has been done. The oiling lasts for about 2 months, and costs about Re. 1 per hundred square feet.

Tar-Macadam.

Although tar-Macadam may be somewhat ambitious for mofussil municipalities, an abstract of the specification for MacCabe’s tar-Macadam, which was kindly supplied to me by the Chief Engineer of the Calcutta Corporation, is of interest, see specification Appendix H, page 75. The cost of a road so laid is Rs. 2–2–0 per square yard, and although sufficient experience is not available to predict its life, some has been down for 3 years and is still good. The materials consist of two parts Pakoor Stone metal, MacCabe’s patent Bituminous binder of Gas Co.’s Coal-tar, and Stagg brand English coal-pitch, in the proportion of 1 of tar to 3 of pitch by weight, with stone chipping, and sand as a top binder.

Kunkar Metal.

All kunkar metal required for metalling or repair work should be collected, screened, and stacked by the middle of May at latest; screening must be done in the dry weather, otherwise the meshes of the screen soon clog up when the kunkar is damp, and the operation is more or less a farce. A specification for this is given below:—

(1) All kunkar must be washed, cleaned, and screened during the dry weather months; and must be of such quality that, being re-washed and rescreened through an expanded metal screen of ? mesh, set at an angle of 45°, shall leave a residue of 80 per cent. pure kunkar. If kunkar of a lower standard is stacked it must either be rejected, or the cost of bringing the metal up to specification, deducted from the price paid.

(2) No kunkar should be measured after the 1st June. All kunkar collection must be completed by 15th May.

Brick Metal.

Brick metalled roads are rarely successful owing to the difficulty of ensuring that the metal is of equal hardness throughout, and especially so in a dry climate, as under heavy traffic the metal soon wears into brick dust, which either blows away in the dry season in the form of dust, or is washed away in the rains; on no account should jhama, or vitrified brick, and red brick metal be mixed, as their degree of hardness is so different.

Morhum & Kutcha Roads.

It is of great importance that excessive slope be not given in morhum or kutcha roads, otherwise they will rapidly gutter during heavy rain. A rise of 1 in 50 to the centre of the road will generally be found to be ample.

Stacking Metal.

In order to control the collection of material it is essential that all be stacked to gauge, or in boxes, and that the stacks be of equal size, thus facilitating measurements.

Consolidation of Metal.

Consolidation of metal must invariably be done as soon after the rainy season sets in as possible, and especially so for kunkar. Any heavy rainfall in a water-bound road after the metal is once laid is invaluable in helping consolidation, as it fills up all the interstices which may be left after rolling or ramming; kunkar should be consolidated by ramming with heavy wooden rammers, although on a new road a roller will be of use in forcing the kunkar in between the joints of the soling bricks, and jamming them into the earth, thus making a solid foundation. A plentiful supply of water should be used in the process of consolidation; this is most essential. Stone and brick metalling should be consolidated by heavy rollers, a minimum quantity of surfacing material being used. It is of great importance to keep the berms well made up against the metalled portion of a road, otherwise the metal will rapidly spread out under traffic.

In all cases it is of the greatest importance that the natural aid afforded by climatic conditions be utilised in making roads; this is a subject the importance of which is frequently overlooked. When the consolidation of metal is seen to be going on after the end of the rains, unless there are exceptional circumstances to justify this, the official in charge may be condemned at sight as being ignorant or incompetent.

Long lengths of road should not be taken up for repairs at a time, as this causes much inconvenience to traffic. A furlong is the uttermost limit admissible.

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