The pre-European Maoris had neither roads nor draught animals, and although there was a primitive and spasmodic form of trade in greenstone, preserved birds, and feathers and fish, they used rafts or canoes, or travelled on foot, usually in single file, over primitive tracks. The pa at Kaiapohia (Kaiapoi), in the South Island, is said to have been supplied with food by relays of porters who travelled in stages between prearranged depots carrying loads of 100 lb or more. The lack of roads obstructed European colonisation. In the early years packhorses had to be used extensively. Bullocks soon arrived from Australia and, in suitable terrain or on the few formed or partly formed roads, they proved to be immensely superior to the packhorses. They could carry heavier loads, needed no shoeing, ate less expensive food, and could be turned out at night without covers even in bitter weather. Thus bullock transport was favoured and, in some instances, continued until the 1920s.

Gradually, however, horse-drawn drays or other conveyances replaced the bullock teams because they were quicker. A horse team could move twice as fast as a bullock team, thus saving drivers' wages. Horse transport lasted for over 60 years. There were many times when the railways, especially in Canterbury, lost traffic to horse-drawn drays, and, less often, to Cobb and Company's coaches. But it was inevitable that steam should enter into road transport. In 1869 and 1870 several Thompson Road Steamers, running on rubber tyres, were imported, but their unreliability, their inability to run on rough roads, and their voracious appetite for coal and water made them quite unsuitable. From 1880 onwards efficient steam-traction engines began to be imported and in certain districts they brought about a minor revolution in heavy-freight haulage by road. In Canterbury, for example, traction engines reduced the journey time and, usually, the costs of hauling wool from the back-country sheep stations. Carting wheat in dray loads to the railhead or stores was uneconomic, especially when the horses were needed for the next season's farm work. The traction engine, which could haul considerable loads, soon competed with the railways, for, among other advantages, there was no need of transhipment at stations or rail depots. Large numbers were used in various parts of New Zealand until the outbreak of the First World War. The traction engine was almost indispensable for hauling heavy equipment from railheads to such construction works as power stations in the back-country areas.

Because most traffic accidents are the product of several factors, the probability of accidents can be reduced in a number of different ways. There is no doubt that the following activities have prevented the increase in accidents that would normally result from increases in traffic density. There are three main approaches to preventing accidents:

1. Education and training of (a) children in school by road-traffic instructors and school teachers; and of (b) adolescents in the principles of safe driving and in good driving attitudes; by (c) refresher courses for older drivers to bring home safe-driving principles and to refresh their knowledge of traffic law; and by means of (d) newspaper, radio television, and other publicity, to draw the attention of all road users both to dangers and to safe practices on the road.

2. Enforcement by (a) adopting reasonable and enforceable traffic laws which, at the same time, are best designed to prevent accidents; (b) concentrating the time and energy of traffic officers on the offences, locations, and times that feature frequently in accidents; and (c) thoroughly testing new drivers to ensure they will not be liable to cause accidents.

3. Engineering of vehicles and roads: Vehicle engineering, comprising (a) regular inspection for a “warrant of fitness” to ensure that the main components of the vehicle are safe; (b) improving the design of the vehicle to give ease of vision and control to the driver and so reduce the likelihood of injury in an accident; (c) fitting safety equipment, such as seat belts.

Road or traffic engineering comprises (a) the design of new roads which are inherently safe (separating opposing traffic flows, eliminating cross traffic, and providing wide shoulders and traffic lanes and good visibility); (b) Improving existing roads by realignment, improving vision, and resurfacing slippery surfaces; (c) Regulating traffic movement by installing traffic signals, traffic islands, road markings, and regulatory signs such as “stop” and “give way” signs; and (d) assisting the driver with warning and destination signs to avoid danger and confusion.

M.R.Pr.

Traffic accidents which result in injury to any person must be reported to the police, and a report on each of these accidents is forwarded to the Transport Department. From these reports statistics of accidents are compiled, and the table below sets out the main causes of accidents reported.

Factors Stated as Main Causes of Accident

Detailed research into traffic accidents both in New Zealand and overseas has shown that rarely can an accident be attributed to a single cause. Most accidents are the product of a number of factors operating together – for instance, a tired driver, smooth tyres, a slightly slippery road surface, light rain, and dazzling headlights might all be causes of one accident. If one of these factors had been corrected, then the accident would have been avoided. The natural tendency is to look for a driving fault when investigating an accident, but it is likely (and studies have confirmed) that factors such as road conditions, weather, and mechanical faults are considerably more important than the statistics given above would show.

There are over 400 deaths and 16,000 injuries from some 9,000 reported traffic accidents on New Zealand roads each year. There are also a large number of accidents which result in considerable damage to vehicles but which are not reported. By comparison with the records of some overseas countries where “damage only” accidents must be reported by law, it is estimated that there are 20,000 to 40,000 damage accidents a year with an average of more than £30 worth of damage to a vehicle.

The number of deaths and injuries increased by 84 per cent and 157 per cent respectively between 1950 and 1964. In the same period the number of motor vehicles has increased and the accident rate (injuries and deaths per 10,000 vehicles registered) has remained almost constant, except in 1964 when there was a sharp increase. The death rate per 10,000 vehicles in 1964 was considerably lower than in 1950.

The following table shows the trend of traffic accidents over the past 15 years.

Unfortunately, the road-accident figures for the half-year, January-June 1965, are disturbing, with 292 dead and 9,000–10,000 drivers, passengers, and cyclists injured. The fatalities for this period show a high increase in relation to that in traffic volume.

It is difficult to compare accident rates in New Zealand with those of other countries, because the reporting of accidents, the number of vehicles, the average milage run, the population, and the density of pedestrians all vary from country to country. Precise measures of these variables are often not available.

The following table compares New Zealand with three other countries and shows that on this basis New Zealand has a low accident rate.

Highway engineering is one of those branches of engineering which has been associated step by step with the progress of New Zealand. Today much has been achieved, but there remains just as much to be done. The engineer will be required to provide surfaces to carry heavier loads on more and more routes; at the same time manufacturers will be producing more and faster vehicles, which will require more road space.

by Harry Lancelot Hume, B.E., B.SC.(N.Z.), M.E.(YALE), M.I.C.E. Chief Civil Engineer, Ministry of Works, Wellington.

The story of road engineering in a country such as New Zealand would be incomplete without reference to the bridge engineers. Recent advances in this field have been quite as outstanding as in those of roadway design. Like many of the early roads, some of the first bridges built in the colony are still open to traffic or have just been replaced, as, for example, the Kawarau Bridge (1962) on the Cromwell-Queenstown route. The old bridge (1880) was a suspension one with a 300-ft span. The Wanganui Bridge, which originally had lift spans, was erected in 1869 and still serves the city. Bridges of standardised design in steel and pre-stressed concrete speed up construction by pre-fabrication methods, and decrease the work to be done on the site. Again, new concepts and construction techniques, such as the use of steel piling in various forms, prestressed concrete piles, or bored piles, have enabled structures to be built where timber or ordinary concrete piles would have been inadequate. Construction by cantilevering out from piers has been recently used on a number of major bridges in New Zealand. This is a procedure which can be used on difficult sites.

As in road engineering, bridge design must be related to traffic requirements. In the early days the approaches to a bridge were of minor importance and every effort was made to secure the shortest and cheapest site. Moreover, bridges were designed for smaller loads than those required by modern traffic. Today a bridge is considered part of a highway and must be constructed in conformity with the curves and alignment of the road. But bridge construction is also designed for other purposes, equally important. The extension of overhead motorways into the heart of Wellington and of Auckland will require many major structures over land and rail.

Of equal importance is road maintenance. Even in the worst of weather, maintenance gangs keep open the traffic routes of the country. Modern highways are designed to stand up to the stresses of heavy traffic, but all roads require regular attention. The magnitude of this work may be appreciated by the fact that maintenance cost in recent years is approximately one-third of the total highway expenditure.

Rigid pavements of cement concrete or bituminous concrete have been generally so expensive that these materials have not been used outside cities; rather than put a strong surface pavement on a relatively poor subgrade, New Zealand engineers have tended to build a very strong subgrade and cover the surface with a light treatment just sufficient to meet the needs of traffic. They have developed the bituminous seal with the large chip. This method produces tyre noise, but it does give at a low cost a strong nonskid membrane protecting the subgrade.

Where the traffic is heavy, or in districts where the supply of chips is not readily available, other types of pavement have been developed. For instance, on the Desert Road, which runs north of Waiouru across the North Island Central Plateau, local material was used to make a bituminous mix which has given very satisfactory smooth riding for many years. On the motorways around Auckland, where the traffic is extremely heavy and tyre pressures are high, an even stronger bituminous pavement has been laid down. On the more congested urban streets and highways the tendency is to put down the high-type concrete or bituminous surface. In cities the most permanent surface used is a bituminous mix on a concrete base. With modern equipment available it is possible to construct either type to a high degree of accuracy and with smooth-riding and long-lasting surfaces. To cope with the weight and thrust of heavy transport buses it has been necessary to provide concrete loading areas at bus stops.

In determining the priority for highway construction, the National Roads Board uses a sufficiency rating which takes into account the various road features, such as width, alignment, grade, pavement strength, surface condition, and shoulder widths. These are compared with desirable roads standards and then grouped to show the sufficiency of the section in relation to safety, structural adequacy, and traffic serviceability. It is said that “in Roman times each legion had an engineer and the roads were well laid in layers with ditches on either side for drainage”. The construction of a modern highway remains much the same; it is still compacted in layers and drained on either side. But the engineer today has a more scientific approach. It is his responsibility to test the soil profile of the various routes and to decide how much use can be made of local materials. In some areas sealing chips, for instance, have to be brought long distances; costs can therefore be reduced if local materials are available. Well-equipped laboratories are available throughout the country to carry out such sampling and testing. The engineer also uses such aids as the California bearing ratio, a device in which performance of the pavements has been related to physical soil constants, or the Benkelman beam, which measures the curvature of the deflection of the pavement. From these tests the engineer is able to calculate the various thicknesses of the selected material and treatment to carry the loading in all weathers. Some materials, like clay, are particularly sensitive to moisture, and their ability to carry loads is greatly reduced when they become wet.

The earliest tracks, apart from those used by the Maoris, were probably made through the bush to enable kauri spars to be hauled down to the beaches for trading and whaling ships. As settlement grew, tracks were developed further afield to provide a rudimentary form of communication by foot or horse. With the discovery of the goldfields and the Maori Wars of the sixties, roadmaking assumed a new importance. The fact that many of these routes are still in use is a tribute to the skill of the early surveyors and engineers who carried out their work under most difficult conditions. Today the problem of the surveyor is less hazardous, owing to the use of a new aid called photogrammetry. By this method plans can be developed from aerial photographs which reveal contours at close intervals, thus enabling road location to be undertaken with sufficient accuracy for contracts to be let.

Before 1930 road engineers had largely to rely for earthmoving on such primitive methods as the pick and shovel, wheelbarrow, and horse-drawn cart, though motor lorries were used to carry away a great deal of the spoil. The coming of the crawler tractor, which was about 100 horsepower, rapidly changed the technique of roadmaking. Larger cuts and fills became both possible and economical and unit costs remained almost stationary, A further advance came with the introduction of the modern tractor (over 400 horsepower), so powerful that hard rock can be ripped up for handling without the use of explosives. Large rubber-tyred scrapers have also been developed as complementary units for moving large quantities of soil and rock at high speeds.

When traffic was horse drawn, speeds were really not of great importance; thus the curvature of the early roads is generally quite unacceptable by modern standards. Improvement of alignment is a matter of cost and the tendency today is to group substandard curves and to change speed value in steps. For many years the National Roads Board has used portion of a spiral or lemniscale for this purpose. In order to improve the riding qualities of highway curves, transitions have been introduced which change the curvature gradually and introduce superelevation. But good road designing is not in itself the answer to all the traffic problems of today. The human factor must never be overlooked. Thus special traffic signs warn motorists of the correct speed for taking curves, and “no passing” lines along certain sections give warning that overtaking is dangerous.

Easy grades were of great importance to the horsedrawn vehicle but were not always possible of attainment. But grades are not nearly so important to the modern high-powered motor cars, though on very steep inclines some commercial vehicles may be forced to drop to a low speed, thereby delaying other traffic. To avoid such congestion and to carry such slow-moving traffic, road engineers in Australia and the United States have evolved the system of an extra up-hill lane. This is now being used with considerable success in New Zealand on the Bombay Hills north of Pokeno and on the new Taihape deviation.