Road junctions and intersections
A road junction is the point at which one road meets another; an intersection is the point at which two or more roads cross еach other. Both junctions and intersections are the worst danger spots in a road system.
The problems of reducing danger at these points are those of cost and space. If junctions and intersections are such that all classes of traffic meet each other at the same level, there is a danger of collision. Almost complete segregation of different classes can be achieved, and the need for users of the same class to cross traffic streams can be avoided.
Пособие по английскому языку для студентов II-III курсов строительных вузов / М.: Высш. школа, 1978. – C.20 |
All forms of road junction can be classified into three groups: multi-level junctions, roundabouts and flyover-junctions.
Multi-level junctions. The clover-leaf, the most typical of these, has already been mentioned. There is need for multi-level intersections where three conditions are fulfilled:
· only a small percentage of the traffic must turn to left or right
· the major volume of traffic is travelling on a fast through route
· the volume of traffic would otherwise be sufficient to justify the provision of a roundabout.
Roundabouts. Unlike multi-level intersections, roundabouts do not enable traffic to cross without dropping speed but pedestrians and cyclists cannot be segregated unless costly over- or under-passes are constructed.
Пособие по английскому языку для студентов II-III курсов строительных вузов / М.: Высш. школа, 1978. – C.21 |
Flyover-junctions.These have been developed chiefly at places where there are no pedestrians. These “flyovers”, which enable high speeds to be maintained, are extremely expensive, costing about ten times as much as roundabout, so it is much better to have ten roundabouts at ten dangerous junctions than a single flyover at a single junction. A combination of roundabout and flyover bridge can be of great value.
Road signs
http://www.liveinternet.ru/users/cdefg/post181491573/ |
In the Middle Ages, multidirectional signs at intersections became common, giving directions to cities and towns.
http://fotki.yandex.ru/ |
New generations of traffic signs based on electronic displays can also change their text (or, in some countries, symbols) to provide for “intelligent control” linked to automated traffic sensors.
http://autokadabra.ru/shouts/61302 |
A. Danger warning signs
B. Priority signs
C. Prohibitory or restrictive signs
D. Mandatory signs
E. Special regulation signs
http://www.pametka.ru/story.php?title=SVETODIODNYE-DOROZHNYE-ZNAKI-OT-PROIZVODITELYA-PO-NIZKIM-TSENAM |
G. Direction, position, or indication signs
H. Additional panels
Traffic control
It is obvious that in existing urban areas much of the congestion is due to narrow streets and junctions which are incapable of taking peak-hour traffic. The solutions of this problem are costly. They include adequate roundabouts and street widening and the segregation of traffic by means of flyover roads, underpasses, bridges and pedestrian subways.
Much of the congestion in urban areas is due to traffic which has no business in the area but is only passing through.
http://blog.william-russell.com/beijings-plan-to-introduce-congestion-charge-to-ease-traffic-problems/ |
http://www.humshaugh.org.uk/?attachment_id=153 |
One-way traffic is a special kind of directional control which is very effective in maintaining the traffic flow in congested areas.
A major cause of congestion in towns is the interruption to the free flow of traffic by cross traffic at junctions. But if the need for traffic streams to cross each other can be avoided then the movement of vehicles will be much easier. This easier movement of traffic can often be achieved by making traffic move in one direction only along certain streets and by prohibiting incoming vehicles from side streets from crossing the main stream. The streets may be either one-way or two-way according to local conditions of traffic or width of carriageway, and traffic at the junctions can be guided by constructing suitably-shaped islands. Besides, one-way traffic can also be introduced where the carriageway width is inadequate for two opposing lines of traffic.
http://www.esi.info/detail.cfm/Sustainable-Options/Recycled-plastic-finger-signposts/_/R-40765_LS90RQ |
The two main objections to street intersections are that they are a cause of accidents and that they interrupt the flow of traffic. The best thing to do with intersections is to get rid of them. If that is not possible they may be improved and made safer but they will always remain a source of danger and delay.
Many accidents are caused because traffic streams of different types, or traffic streams travelling in different directions are using the same carriageway, and these accidents can be avoided either by reservations between traffic lanes, or by vertical (or “grade”) separation.
In many cities in America and in Europe segregation of traffic is achieved by means of flyovers or underpasses; at some junctions there are even three different levels. Each has its advantages and disadvantages according to the circumstances. Flyover structures are not always aesthetically pleasing while an underpass may be more expensive to construct. The separation of fast and slow traffic from the heavier and faster traffic is most desirable not only in the interests of freedom of traffic movement, but also of safety. This ideal is not easy to achieve.
Urban traffic control will be of benefit to the general public in the district concerned and will result in greater comfort for road users of all classes, as well as bringing economic advantages to the community as a whole.
Road safety
Road traffic safety refers to methods and measures for reducing the risk of a person using the road network being killed or seriously injured. The users of a road include pedestrians, cyclists, motorists, their passengers, and passengers of on-road public transport, mainly buses and trams. Best-practice road safety strategies focus upon the prevention of serious injury and death crashes in spite of human fallibility. Safe road design is now about providing a road environment which ensures vehicle speeds will be within the human tolerances for serious injury and death wherever conflict points exist.
http://www.otradny-13sad.ru/index/profilaktika_detskogo_dorozhno_transportnogo_travmatizma/0-50 |
Major highways are designed for safer high-speed operation and generally have lower levels of injury per vehicle km than other roads.
Safety features include:
· Limited access from properties and local roads.
· Grade separated junctions
· Median dividers between opposite-direction traffic to reduce likelihood of head-on collisions
· Removing roadside obstacles.
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Modern safety barriers are designed to absorb impact energy and minimize the risk to the occupants of cars, and bystanders. For example some road fixtures such as road signs and fire hydrants are designed to collapse on impact. Highway authorities have also removed trees in the vicinity of roads; while the idea of “dangerous trees” has attracted a certain amount of skepticism, unforgiving objects such as trees can cause severe damage and injury to any road users.
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