1932-06-25 — Page 2

Page

"HONG KONG DAILY PRESS, SATURDAY, JUNE 25, 1932.

ENGINEERING AND BUILDING

Modern High-Grade Roads and Their Construction.

SOME

NOTES ON THE WIDE RANGE OF AVAILABLE MATERIALS.

efforts of Metcalfe, Telford, and Macadam. Metalfe's efforts found expression in the numerous rands which, commencing, with one from Harrogate to Boroughbridge 1703, continued until many miles of Yorkshire bad been blessed with ronds the equal of which had not been seer, before,

"

nb the commencement of the nine teenth century, undertook an over- haul of existing ronds in Scotland which were not suited to the use In addi- Road Puginring" in its more who had been led to anticipate in of either man or beast. modern

is a matter of provements following the imposition, he constructed many bridges unly a century and a half of pro- tion of tells and the introduction and harbours, and pointed out that AT. But it is interesting to re of carnpike system, which found its the existing ronds were not of any wel that in 1796 'paper was rond. "rigin at the beginning of the great advantage to the developing community. It is placed on record by Phillips before the Royal So. Jeighteenth rentary,

The big advances in roadtaking that in the space of eighteen years einly in which the and state of the roads was the subject of a bitter in this country were, however, woon he completed over 900 miles of ropes complaint on the part of the users, to be made through the successive and over 1,000 bridges.

Copyrigh

Telford's method was that of Jaying a foundation of closely not stone asks, overlaid with some din of smaller stones or gravel, in turny surmounted by smaller stones and gravel

THE MACADAM METHOD..

WES

some.

MILLING CUTTERS AND REAMERS.

and

A revision of the standard speci floation for milling Cutters roamers unginally published in 1040 has been issued from the Bri-, tiah Stanards Institution,

1

RUST IN STEEL

BRIDGES.

*

THE BEST REMEDY.

i

MOTOR ENGINES.

COMPRESSION-IGNITION TYPE.

At the time when Metcalfe com-

Farticulars are now available, of mened his important work there

This revision, which has become la is common knowledge amongst the new compression-ignition en- ast Ayrshire boy who

that wrought-iron destined to honoured memory for accessary owing to recont changes engineers the grat rough work which is course in practice, enters for a somewhat bridges are seldom badly affected gino of Mesars, W. H. Dorman end of time be initiated and carried bigger key in the case of the larger by corrosion, which, on the other Co., Ltd., of Stafford, which con out. This was John Macadara, diameter bors, and the tables of hand, affects steel bridges readily statutes the Intest entrant into the

Wrought-iron rast takes the form Whis name becaus immortalised dimensions for keys and keyways by hir method of road construe for arbors have therefore bent of small spherical particles, which field of motor vehicles This is at Telford some years later, in fiction, which differed from that of amended and extended as provide, are easily brushed through present a four-cylinder, unit. in

for arbors up to five inches in wibration, while on steel rust a Telford, though it was to

diamecer,

penre na large sheets or laminations two sizes, the smaller of which de exter anticipated by Phillips.

One of the important features of of oxide, sometimes as much as in valepa 78 5.3.p.. while the larger

type gives 20 b.p.h. Mandam insisted, in spite of

the revision is the addition of in thickness.

From the dat it appears dias considerable opposition, that the

A further point is that with steal these units are developing the heavy stone foundations of Telford standard dimensions for milling

this deterioration is usually localisential characteristics of road were unnecessary, and that the machine spindle noses and arbors waturi subit would carry ren- of two sizes, tagother with the ed, as, for instance, in places where vehicles, including high torque at sonabh longs provided that, by dimensions of adaptors for using the steel is in contact with earth. low and medium speeds with me. or at points where wooden floors chanical and thermal silence, prope drainage, it was kept suit-old pattern arbors in the now spindlea. This axtension has been ably dry. Exhibiting m marked pre-pied by an addition to the title cover steel stringers or door, beams. while the fuel consumption does In the view of thas excellent annot rise at all rapidly until thu forem for a soft and yielding of the specification (No. 15-1881), thority, Mr. McKibben, wherever apood is considerably increasedà foundation into which layers of which can be obtained from the rust is found, the best remedy is

Formerly this type of power unit to apply new metal" at brake stone could be compressed.S.I., 95, Victoria-street, London,

once by by mans of a comparatively heavy s.W. 1. price 2a. 24. post fren.

either the oxyacetylene or the elec has been noted for what has beer termed the Diesel thump, but the roller, he raaiutained that, a road

tric welder. He mentions a steek new units ran a moderate speeds lasta much longer over tb morues

bridge which, over a railway, was with a smoothnew which may be than when made over rock.

badly affected by

said to approximate to that of a 4 locomotives passing beneath.

high-grade petrol unit. Moreover, The old "Range plates ware re the operation of hand-starting has moved, two or three at a time; ths been much simplified, so that suf steel beneath was thoroughly clean-cient speed can be reached to an- ed with wire brushes, and the old, auro initial strokes.

crankensc exposed rivet shanks, wore chipped Both cylinder and off. Then new flange plates were castings are of robust design, t

the required degree of welded on in place of the defective ensure mombers without disturbing, ap rigidity. The cylinder hends are preciably, the concrete arches in of the Ricardo design, involving' a contact with the girders, except sook chamber. Excessive pressures far as

zas necessary to provide are avoided by the use of a ne places for clamps.

orifice which ensures a delayed ne- tion in Aring. The cylinder heads are codi in pairs, while very ad- equate lubrication is a feature of

For Constructural Work of Every

Description

Use Green Island Cement

WHERE GREEN ISLAND CEMENT IS MADE.

VIEW OF THE GREEN ISLAND CEMENT

TAKEN FROM THE SEA.

Issued by the

A GENERAL

WORKS

GREEN ISLAND CEMENT CO., LTD.

SPECIFY

2ND FLOOR

EXCHANGE BUILDING.

Berger Paints Varnishes

Enamels - Distempere- Lacquera

1760

FOR YOUR CAR

Proxcelin

THE CELLULOSE FINISH

Agents-W. R. LOXLEY & CO.

If. B... AtkinsORD

welve onçes

[hcombers of the Ò«M«A«,

COMPLETE ELECTRICAL INSTALLATIONS

with

C. M..A CABLES.

Advice and Estimates. given

free on all types of

LIGHTING & POWER INSTALLATION

by an experienced

ELECTRICAL ENGINEER

retained at our Hong Kong Branch

The General Electric Co. (of China), Ltd.

QUEEN'S BUILDINGS,

HONG KONG.

It lok some time before enthu- tenance. Hiush for Macadam's method could

While bitumen is a widely dis- bo bound, but in course of time tributed product, no asphaltic rock he came into his own. His nttens found in this country. That which is so largely and successfully tion was particularly attracted to limestone as a road making matoused is therefore mainly imported Evitzerland, France, and rial, aa this, in the course of lay from ing made, auficient powder to con- Sicily, but is mined mainly under statate, when damped, a cement-British control, and with British ing layer between the crushed capital. The usphaltie rock com- prises limestone, which is impre Jump The

"macadam LATI thus passed into general use for the gnated with bitumen up to from 7 It ie tablu to to 15 per cent. type of rond,

composition, and Modern times have called "for variation in considerable improvements upon therefore in road-making qualities, the limestone which was required,bus uniformity is attained by the and the dust problem is still one suitable blending of varicus grades, which needs particular attention so that the mixture contains from in these days of rapidly increas. 9 to 11 per cent, bitumen.

The rock is brought over to this ing volumes of high-speed motor trah. The modern solution, how-country ground to a fire powder, ever has been the application of and carefully blended, afterwards a bituminous binder, of which tar being hosted to expel moisture and ia relatively cheap and readily light oils. It is the laid on a concrete foundation at a tempera- available example.

degrees F., As a material for binding road sure of 300 to 350 metal, tar was used many years uniforirly distributed by raking, ago but its surface application which involves some manipulative for dust prevention is a much skill, and then compressed either by light roller, more usually, mor modern advance. Applied na An layer in the hot, form, it has by, tamping with heated tools. considerable penetrating proper-

Under this compression a very dur- ties and roads thus treated become able material is obtained, in fact, pradically dustless at moderate such roads can well be numbered among the best which can be laid down. The system exemplified in the familiar Val de Travers has large vogue, and in attained a

London thoroughfares numerous has for a long time withstand very successfully the heaviest traffic.

U

Nedless to add, many prepara- tion embodying similar materials have been used, including one or other forms of crude oil. This is insporated with the road metal, who with tasmaundam this pieces of bad meth are coated with tar prie to being laid and rolled.

CONCRETE AS A ROAD

· MATERIAL..

A chon per method of uning natural rock asphalt is in the form of **Matrix,"

compound of natural rock and Trinidad Lako asphalt, this being used for surface dressing, sealing coats and for Te deal with modern heavy grouting, while more recently a motor traffic and that of other synthetic asphalt, the nature of British heavy road vehicles with their de- which is controlled by struitive effect on almost any type Standards Institution specification, of road some material of a more provides a durable road at a some rigid nature, and therefore cap-what lower initial cost. able of withstanding the wave pro- duding affecta, was obviously re quird Road inequities are due to the movement of the road mate- rial, and the required rigidity wasi forthcoming in Portland cement Concrete.

tages are

numerous,

The use of this material was at fit slow in this country, but its application has made rapid ad vantes more recently. Its advan

As a form of construction of moderate cost it contines many features. These in- clud cleanliness and noiselessness, low tractivo resistance and low maintenanca cost.

While on steep gradients there"

RECONDITIONING OF ASPHALT."

It is generally conceded that modern requirements demand a smooth somewhat resilient rond material, and this is met by the several forms of asphait. This material; however, suffers from the disadvantage that while excellent under ideally clean conditions, the accumulation of oil films and dust induce in wet weather a dangerous slipperiness. Skidding. then be-) comes common, and needs to be avoided.

This is a matter which can be, is the tendency to slip this can be and is, got over by the incorpora- Compensated for by the addition of tion into the surface of a propor- line of selts. The material ition of hard chippings which have early handled, can be put down been coated with a small propor with comparative smoothness, the tion of bitumen. These are added joists being rendered watertight by and rolled in before the naphalt has begun to set off, and thus add con- the application of bitumen.

What concrete may lack in re-siderably to the grip of the tyre Bilbuco can be added by the use of on the road. Very definite speci- reinforcement, which as a modern Actions exist for this material, requirement is manufactured in and considerable advantage has ac Cornient rolls, and is enaily laid crued by its use.

There is again a measure of soft- on the road: Its first and most im portantreffect is that of more wide-ness attaching to asphalt as a road material, and this in the heat of ly distributing the load over large area of the subgrade. It is summer gives rise to a wavinose the In subject to cracking, and offers results of which are far from

the motorist. The cemiderable resistance to warping, pleasure to

elimination of these corrugations

The preparation and handling of

Д

the larger amounts of materials from an asphalt road is thus

matter of importance. In this con- involved in rond construction CL2891LAS range of special nection reference may be made to types of machinery. These include the. Greco " method, whereby such exavators, locomotives, rock crushroads can be reconditioned and to their "original and grinding mills, cement brought back

efficiency. mitera tipping wagons, compress- This le eficcted by a special heat- ed air machinery, Herrens, tar heller's and sprayers, "and rollers, ing machine in which superheated In every case these are products air plays over a portion of the road, bringing it to a degree of of specialised manufacture, every

sideration: being given to the softness which enables it to be roll- ed out mouth, and permits also tasks to be imposed upon them.

The quick handling" and trans- the addition to surface materins. portation of these materials calls By the application of the heated for the use of light,, mobile cranes air, the road material is softened, of special design. n number of nfter which it can be raked over examples of which are available, level and further material of like notably one by Mesars. R. H. Neal, nature added, the degree of soft- ness allowing of perfect incorpora- of Ealing,

tion of the new material into the efficient BITUMINQUE, ROADS. old. In simple and While the term bituminous as manner the unevenness is smoothed applied to road materials enco out and original thickness restored, covered tar and pitch, modern with very little interference to

than single: usage of the term limits it to traffic-not more materials which are soluble in working day. carbon disulphide, and are obtain. Such quick repairs to a rond oils or ground which aanbodies the desirable pro- ed from earth sphalt. Theat materinis produce portics of asphalt should make an Fonds of a resiliest nature which appeal to road engineers, and thus are impervious, provide smooth help to maintain efficient ronds surfaces, and are both noiseless and comparable with those of any coun dretless. They are of cusy main try in the world.,

from

the unit.

Transfer of Stress. Naturally, the dead load stresses in the bottom flanges were large, so

The mounting of engines, an that it was necessary in applying existing chassis designs has gener the new plates to give them an in-

divergent views have been held, itial dead load stress comparable ally preved a matter upon which with that in the bottom flange but arrangements have been made angles from which the corroded in these units to facilitate His plates were removed and to whien

sometimes difficult" problem. the new plates were walded."

made at 3in intervals on each side,

This transfer of strew was ne new plate to the old angles. Then, companied by first clamping the with two welders operating, a 30in The cooling and consequent shor- tening of the plate transferred anch side at one end of the new some dead load stress from the old continuous liet, was deposited on plats to weld it to the angles. With angles to the new platos, the plate clamped in position, and i Clearly this process of heating thus welded at one end, it was need be applied only where the heated with torches until its length unit dead load stress is large. The hod increased by a pre-determined increased length in inches neces calculated amount, and, whilst sub sary may be easily computed by jeet to this heat, the free end of multiplying the desired unit stress the plate was welded, also within pounds per square inch by the two 30in continuous welds, after length of the plate in inches and which intermittent welds were dividing the product, by the mo

(Vontinued un next cobrimn. }''* dulus of strel,' 30,000,000,

THE EXPRESS LIFT CO., LTD.

WITH WHICH IS INCORPORATED THE BUSINESS OF

SMITH, MAJOR & STEVENS, LTD./

EXPRESS SMS

LIFTS

MODERN LIFTS

FOR

MODERN BUILDINGS

SPEEDY RELIABLE SERVICE

FOR DETAILS APPLY TO

THE G.E.C., Queen's Building, Chater RoID.

EVERYTHING

£.&.c.

ELECTRICAL

"