is made for the levying of a special charge, known as "betterment," upon such property, the basis of calculation being 3 per cent. upon half the enhanced value. No charge is made until the enhanced value has accrued. The principle of “betterment" was conceded by Parliament for the first time in London in the Tower Bridge (Southern Approach) Act, 1895. All other street improvements are known as "local improvements," and are executed by the metropolitan borough councils, generally under the powers conferred by the Metropolitan Paving Act, 1817, usually known as Michael Angelo Taylor's Act, which gives compulsory powers for the extension and widening of existing thoroughfares. Occasionally these powers are not sufficient to meet particular cases, and then the borough council obtains special parliamentary powers, usually by means of a bill promoted by the London County Council. The City of London is somewhat exceptional in regard to street improvements. The Corporation carries out most of the street improvements in the City with or without a constribution from the London County Council, under authority conferred upon it by special legislation. The cost of local improvements is borne by the metropolitan borough councils, the London County Council frequently contributing. Bridges, embankments, ferry and tunnels.-The London County Council maintains the Thames bridges (other than railway bridges) in the County outside the City. The Council also maintains Deptford Creek-bridge and the minor county bridges, i. e., the bridges over tributaries of the Thames carrying main roads that are not privately maintained by railway or canal companies. The City Corporation maintains the four bridges over the Thames from the City. The Victoria-embankment is maintained by the London County Council; the Albert, Chelsea, and Grosvenor-road embankments are maintained by the metropolitan borough councils. The river walis of all the embankments and the adjoining footways of the Albert and Chelsea embankments are maintained, cleansed, and lighted by the London County Council. The London County Council maintains Blackwell-tunnel, Rotherhithe-tunnel and Woolwich-ferry for foot passengers and vehicular traffic, and Greenwich-tunnel for foot passengers. Road Board.—The Road Board was constituted by the Development and Road Improvement Funds Act, 1909, for the purposes of improving the facilities for road traffic in the United Kingdom and the administration of the Road Improvement Fund. The Board consists of five members, who were appointed by the Treasury in May, 1910. It has power to make advances to county councils and other highway authorities in respect of the construction of new roads or the improvement of existing roads; and to construct and maintain new roads. Where an advance is made in respect of a new road, the Board may also contribute towards the cost of its maintenance. Advances may be made either by way of grant or loan. The expression "roads" includes bridges, viaducts and subways. The revenue of the Board is provided by the road improvement grants which are derived from the tax on petrol and the increase in the duties on motor cars, imposed by the Finance (1909-10) Act, 1910. The Board has power to borrow on the security of the road improvement grants up to an amount which shall not require for debt charges a greater sum in any one year than £200,000. In making advances, the Board has decided in the first instance to give priority to applications for advances required for dealing with dangerous corners, curves, cross-roads and narrow roads which have no footpaths and for improving and strengthening the foundation or crust of existing important roads. In apportioning the amounts available for advance, the Board have stated that they will have regard, inter alia, to the rates levied for highway purposes with a view to giving the most favorable consideration to the authorities whose rates are relatively high by reason of efficient and liberal administration, or by reason of rateable values being comparatively low. The first list of grants was announced in Feb ruary, 1911, and other grants have since been made. The amount issued from the Consolidated Fund in the year ending 31st March, 1912, to the Road Improvement Fund was £1,209,859, of which £613,957 was in respect of motor spirit duties and £595,902 in respect of duties on motor cars. LONDON COUNTY COUNCIL LONDON, ENGLAND ENGINEER'S DEPARTMENT August, 1912. VICTORIA EMBANKMENT-EXPERIMENTAL PAVING WORKS Trials of various kinds of roadway paving, 1905-9 Since the year 1905 the London County Council has carried out a series of experiments on the Victoria Embankment with a view of ascertaining the qualities of various paving materials, with special reference to durability, and to the reduction of the dust and mud nuisance inseparable from ordinary macadam with which the roadway was, since its construction in 1870, until a double line of tramway was laid in 1906, paved for its entire width (with the exception of some short lengths of experimental tar macadam laid 1905, see below). The traffic on the Embankment amounts to an average of 10,152 vehicles (excluding tramcars) daily (from 8 a.m. to 8 p.m.) and the average width of the roadway is about 64 feet including channels, of which, however, 17 feet is occupied by the tramway lines. Owing to the frequency of running, and the speed of the tramcars, this width of 17 feet which is paved with granite setts is not much used by ordinary vehicles. The effective width of the roadway for ordinary traffic therefore averages 45 feet, and the volume of traffic amounts to 159 vehicles per foot of width over the whole roadway, or 225 vehicles per foot of width if the area occupied by the tramlines be excluded. It is believed that no other road constructed of ordinary macadam ever carried such a volume of traffic per foot of width. For purposes of comparison it may be pointed out that the traffic in the Strand opposite the Law Courts (wood paving) amounts to 311 vehicles, and that in Ludgate Hill (also wood paving), in front of St. Paul's Cathedral, to 296 per foot of width. The list of experiments arranged in chronological order is as under: 1905 In November three pieces of about 700 square yards of tar macadam were laid down near Cleopatra's Needle, the materials used being respectively limestone, slag and granite. The first and the last broke up almost at once. The second piece, reduced in area by tramways, laid by Messrs. Constable, Hart & Co., Ltd., of Clarence House, Arthur Street West, London Bridge, E. C., remained in good condition, and with a very small expenditure in repairs, until the autumn of 1908, when indications of failure were noticed, and in the last six months of 1909, the deterioration was more rapid, necessitating considerable patching, until in 1910 the portion remaining after the tramway track had been formed (an area of 484 square yards) was taken up and replaced with Trinidad Lake Asphalte. 1996-As a consequence of the promising results of the previous year's experiment, Messrs. Constable, Hart & Co., were in June allotted a larger area of some 3000 square yards in front of Temple Gardens, at a price of 6/9 per square yard, including excavation of existing pavement and two years' maintenance. At the same time an area of 797 square yards was given to the Trinidad Lake Asphalt Paving Co., Ltd., of Townmead Road, Fulham, S. W., who laid down an asphalte roadway on a thin base of asphalte "binder" instead of concrete near the east end of the Embankment. The price, including excavation of existing pavement and two years' maintenance, was 9/- per square yard. NOTE. The contract terms for this asphalte, as well as Messrs. Constable, Hart & Co.'s material given in the preceding paragraph were subsequently varied. A short length of macadam treated with a patent solution and mixed with finely crushed Buxton limestone was laid at a cost slightly exceeding ordinary macadam near Charing Cross Station in July. This was known as "Butterfield's" paving. The results were unsatisfactory and it was taken up. In August, the Val de Travers Asphalte Company applied for permission to lay a trial length of asphalte macadam-consisting of the natural rock asphalte or limestone impregnated with bitumen, as excavated from the quarry and broken to macadam size, rolled solid under a roller. So much doubt was felt of the lasting quality of this paving that it was made a condition of the trial that in the event of failure to last two years the cost of the experiment should be borne entirely by the Company, and as a fact, the paving was removed and the macadam reinstated at the cost of the contractors within twelve months of its being laid down. In September the Tarmac Company laid in front of Whitehall Chambers about 700 square yards of their variety of tar macadam at a cost of 4/6 per square yard, including two years' maintenance. Of these five different pavings laid down in 1906, one, the Val de Travers, as stated above, failed entirely to stand the heavy traffic, and after many repairs, was removed. Another, the "Butterfield," only lasted a few months, while the Tarmac shows but little advantage over ordinary macadam. The remaining two, the Trinidad Asphalt Company's and Messrs. Constable, Hart & Company's gave promise of lasting. 1907-In the summer of this year a further area of 8855 square yards was laid by Messrs. Constable, Hart & Company in tar macadam (of slag) at the price of 7/- per yard, including the cost of maintenance for five years, but exclusive of excavation. This piece of paving has not given very satis factory results. 1908-So unsatisfactory was the condition of the tar macadam laid in 1907, when, in the early summer of 1908, further pavement works were contemplated, that the above named firm declined to lay any more tar macadam, expressly stating that the traffic of the Embankment was too heavy for paving of that class. It is only right to add that Constable's tar macadam, although unequal to the heavy traffic of the Embankment, has given good results on roads where the vehicular traffic is lighter. The period of maintenance of the area laid by the Trinidad Lake Asphalt Company in 1906 expired this year (1908), and as the paving had shown no sign of failure was renewed for three years further at the rate of 6d. per square yard per annum. 7650 yards more of the same pavement were laid down in detached areas at a cost of 9/- per square yard, including the cost of maintenance for five years, but not including excavation. A small experimental piece 670 yards in area was put down by the "Roadamant" Company at cost of 8/- a yard, which covered excavation, two years' maintenance and the liability to remove the paving and restore the road, in the event of the former failing. The paving consisted of about two inches of a hard asphalte concrete laid on six inches of ordinary concrete. 1909-During this year the deferioration of the tar macadam laid in 1906 and 1907 went on at an increasing rate, and it was found necessary to remove some 3000 sq. yards of it, and replace it with Trinidad Lake Asphalt. To the Trinidad Lake Asphalt Company was also given during the year further areas (of ordinary macadam), amounting in all to 12,146 square yards, to pave at the same price and under the same conditions as before. 1910-Owing to the erection of certain refuges on the Embankment, and their possible effect on the traffic conditions, the terms of the contract with Messrs. Constable, Hart & Co., dated 14th May, 1907, were varied so as to provide for the maintenance period of their paving terminating on 20th of October, 1911, this being ten months earlier than originally fixed, on condition that before the Council undertook the maintenance Messrs. Constable, Hart & Co. would put in thorough repair the whole of the area for which they are responsible. In this year the last remaining portion of macadam, an area of 1293 square yards, was taken up and replaced by soft wood paving laid by the Improved Wood Pavement Company, at a rate of 11/- per square yard including one year's maintenance, and the excavation of the existing roadway. 1911-Agreements were entered into with the Trinidad Lake Asphalt Paving Company for further maintenance for one year of the area laid down in 1906 with a two years' maintenance and extended in 1908 for a further three years expiring 16th July, 1911; and also with the Improved Wood Pavement Company for the maintenance of their paving laid down last year for a period of 15 years at 9d. per square yard per annum. In October of this year Messrs. Constable, Hart's maintenance period for work done under Contract dated 14th May, 1907, expired. 1912-During the current year orders have been given to the Trinidad Lake Asphalt Company and the Roadamant Company to replace with their respective materials the tar macadam laid by Messrs. Constable, Hart & Co., 5612 square yards being given to the Trinidad Company and 3421 square yards to the Roadamant Company, certain granite crossings and channelling being taken up at the same time. The paving laid by the Roadamant Company this year varied somewhat from that laid by them in 1908, the 2-inch Roadamant being laid in two thicknesses without the concrete foundation, experience having shown them that where the macadam foundation is good it is more resilient than concrete. The total area of Trinidad Lake Asphalt now laid amounts to 29,683 square yards, Roadamant total amounts to 4091 square yards, and the Improved Wood Pavement Company's area is 1,293 square yards. An agreement is being entered into with the Trinidad Lake Asphalt Company for the maintenance for a further period of years of their paving as the several contract periods of five years expire. GENERAL It is as yet too soon to speak definitely of the "Roadamant" paving, but as regards the other pavements tried, the Trinidad Lake Asphalt laid on a binder course has undoubtedly proved the best under the traffic conditions of the Victoria Embankment. It is much cheaper than the usual asphalte pavements consisting of rock asphalte laid on concrete; its surface appears, so far, to wear equally well, and the substitution of an asphalte "binder" course under the hard asphalte top coating instead of the usual concrete bed appears to some extent to reduce the noise of traffic. A brief description of this asphalte and the manner of laying it, is appended: The process adopted is as follows: The existing roadway is picked up sufficiently for a base to be left which will conform to the proposed contour and grade of the finished pavement 41⁄2 inches (four and one-half inches) thick to be laid thereon. This base is consolidated by rolling with a tenton steam roller. On the base is laid, in two layers, Bituminous Concrete (or Asphaltic Concrete) 3 inches (three inches) in thickness. This concrete is composed of broken stone carefully graded with a proportion of fine stuff or filler, mixed with a sufficient quantity of Trinidad Bitumen or asphaltic cement and the bitumen and the stone being separately heated by special machinery at the Works, it is brought on to the street at a temperature of about 300 degrees Fahrenheit. On the street it is raked to the required thickness and contour and then rolled with steam rollers. On the surface so formed is laid a wearing surface of Trinidad asphalt, which, after receiving its ultimate compression, will have a thickness of 11⁄2 inches (one and one-half inches). This wearing surface is composed of Trinidad Bitumen, Silica, or sharp sand and Portland Cement, in about the following proportions: Bitumen.. Portland cement. 11.50% 15.00% 73.50% The Silica takes the place of the firm limestone present in natural rock asphalt, and is said to make the surface. less slippery than that of natural rock asphalt. It is to be observed that this system of paving, which practically dispenses with foundations, can only be used in streets, the beds of which consist of hard core, or have been consolidated by continued traffic. It could not be employed, without an additional foundation, on an entirely new road. SOUTH LONDON AND SIDCUP TRIAL PAVEMENTS On the motor bus route between Victoria Station and the Kent County boundary at Sidcup various materials for surfacing the carriageway have been used, including soft wood, hard wood, ordinary granite setts, specially dressed granite setts, granite waterbound, blast furnace slag coated with Carmarco and Mexphalte. The particular lengths on which the above are laid are shown on the sketch. At the Kent County boundary the trial sections were laid by the Kent County Council under arrangement with the Road Board. The object which the Road Board had in view was to secure a service test, under uniform conditions, of a number of trial lengths of roadway laid down under the general direction and supervision of the advisory Engineering Committee of the Board, so that a record of comparative results could be obtained in a better and more reliable manner than is generally obtainable in the cost of road surfaces laid down in the ordinary course of road maintenance in different parts of the country. The total length of the trial sections is 2490 lineal yards, with a superficial area of 18,420 square yards. A traffic census taken for the week ending August 12, 1912, records an aggregate weight of 3547 tons per day. Name plates have been fixed at each end of the sections denoting the nature of the material and by whom laid. An interim report has now been published on the behavior of the various materials and methods of construction under trial, and can be obtained from Messrs. Waterlow & Sons, Ltd., London Wall, price 2/-. A short description of the 23 sections is as follows: Completed 1. Single pitch grouting laid in place of wornout waterbound granite...Sept. 14, 1912 2. Single pitch grouting laid in place of wornout waterbound granite...Sept. 21, 1912 3. Single pitch grouting.. 4. Double pitch grouting. 5. Durax armored paving. 6. Plascom.. 7. Cormastic... 8. Kentish rag tarmacadam. 9. Tarred slag macadam.. 10. Tarred slag macadam.. 11. Tarmac... July 3, 1911 July 11, 1911 July 8, 1911 July 7, 1911 .Aug. 5, 1911 July 13, 1911 July 22, 1911 .July 20, 1911 .July 27, 1911 12. Single pitch grouting laid in place of roadoleum. Sept. 28, 1912 13. Rocmac.. .Aug. 3, 1911 14. Tarmacadam. Aug. 5, 1911 15. Tarmacadam.. .Aug. 4, 1911 16. Tarmacadam. 17. Roadamant. July 26, 1911 July 24, 1911 18. Lithomac.. 19. Pitchmac or pitch grouted macadam. 20. Natural asphalt matrix and granite.. .July 10, 1911 .July 11, 1911 21. Natural asphalt matrix and granite laid in place of natural rock SPECIFICATION OF WORKS to be done and materials to be used in preparing foundations and laying with Asphalte the Carriageway of Materials and Labor ... 2. The Contractor is to supply all labor and materials, tools, tackle, implements, cauldrons, furnaces, firing, and everything else necessary for the proper laying and completion of the Asphalte surfaces and their foundations. All of the materials are to be of the best quality in their several kinds, and are to be used in the most approved and workmanlike manner. The Contractor shall pay his workmen such rates of wages as are considered fair in the Trades. Existing Pavement 3. The existing pavements will be removed by and at the expense of the Contractor, and will become his property, and the price allowed for such must be inserted in the form of tender. |