Traffic jam

30-01-2015, 11:42Print
The concept Traffic jam (briefly traffic jam) calls a very stopping or to the shutdown come traffic flow on a street. As one of the reasons for it is valid a too high number of vehicles per time unity (or per distance length). Nevertheless, the causes for a traffic jam are not explicable with it only. In contrast to the stop the traffic jam counts to the fluent traffic.

Signs 124 of the traffic jam
Traffic jams – also those on waterways, railroad tracks, on airports or in the airspace ("waiting loop") – are a research object of the traffic sciences. Escape routes for foot walkers in buildings and with big events are formed for the reduction by traffic jam danger broadly and liquidly, numbers of visitors limited.

Traffic experts make a distinction between "traffic jam" and „to stopping traffic”. In Switzerland, for example, it is spoken "in this subject" of a traffic jam if the traffic flows at least for one minute with less than 10 km/h. If the speed lies in the area between 10 and 30 km/h, one speaks of stopping traffic.


Traffic jam causes on highways
Typically the capacity of a street lies with from 1500 to 2500 vehicles per hour and track. The capacity, e.g., can be lowered by unfavorable weather like rain, snowy ice or black ice as well as ineffective behaviour of the road users, for example, by show desire. From it can develop traffic jams from Nothing with which to the road users also after the end of the traffic jam the cause remains concealed (in contrast to accidents in which one can recognise the scene of the accident with the driving past as a cause).

A locally reduced capacity of the traffic route by events like trace blockages on the basis of men at work or accidents as well as roadway choking passages, for example, before tunnels favour the traffic jam origin even further. Such a capacity-limiting choking passage of the traffic route is also called bottleneck.

But also a raised traffic amount can be responsible for traffic jams. Reasons for it can be a rush-hour traffic, holiday traffic (especially at the beginning and at the end of holidays as well as samstäglicher "bed change" in holiday areas) and big events.

Traffic jam recognition
Visual observation
About voluntary traffic jam dispatch riders, police stripes, cameras and helicopters streets and traffic interchanges are observed visually.

Stationary logging system

Traffic flow sensor in the federal motorway 5
By means of firmly mounted sensors in the highway the traffic flow is measured objectively. On this occasion, only the left lane is supervised, because about the parametres Distance and Speed on the left track on the traffic density of the other tracks can be closed. On German highways a sensor is on an average all 4 kilometres, so that here a total of approx. 4000 sensors are in use an application.

With this modern procedure become in vehicles carried along (mobile phones) or built-in devices (i. d. R. with a transmitter equipped GPS receivers) to the measurement of the traffic speed and the holiday season uses. The procedure Floating Cellular Data with the mobile phones is more imprecise than GPS, however, around a lot more favourably, because no additional hardware (mobile phones), infrastructure (aerials) or net load (sending of data) is necessary and for general statements exactly enough.

The network operators make anonymous the signals of the mobile phones and let them analyse by special companies on speed. These data help and base for most Intelligently Traffic of system (ITS), like active traffic control, emergency and Evakuationsmanagement, traffic jam travelling round, time estimate. It offers a real time picture of the topical traffic events; advanced software will forecast on grounds of the real time data also congestion and traffic jams (predictive).

FCD procedures by means of mobile phones have compared with customary systems (sensors, cameras, etc.) big advantages:

Cheaper, because no additional devices or networks are necessary
Not only highways, but also side streets are grasped
No installations in the route.
There are with regard to the use of these data data protection-juridical doubts.

Traffic jam announcement
Traffic jam warning arrangement

Change traffic signs in a sign bridge
Warning of the road users can happen with the help of suitable danger signs or by the display of texts. In addition, speed limits can be arranged or Ausweichsrouten be suggested. With God's hard traffic jam Bernardino route is suggested, for example, the San. Traffic jam warning arrangements mostly dispose of an automatic recognition and are used in sign bridges in the form of change traffic sign.

Traffic jam announcements are read out in the travel news and are sent about TMC (Traffic message channel) in the non-audible area of the VHF signal in digital form. Indeed, the TMC area is very narrow, so that all announcements are transferred only possibly all fifteen minutes. Because it seems, moreover, often that a receiver misses an announcement, the receipt of the TMC announcement can be considerably delayed. Traffic jam announcements about TMC can conceive from navigation systems and are processed.

Other info canals
Traffic jam announcements are published in the teletext and on the Internet by different suppliers. Besides they can be questioned individually about mobile phones. Moreover the position of the requesting is automatically localised and further information about the seaway is questioned.

Behaviour in the traffic jam
Because a traffic jam also rescues accident risks beside delays, there is of other interest groups of the tips to the driveability which mostly are as follows:

On the highway switch on the hazard lights and observe the traffic.
Gliding brake to avoid a rear-end impact of the following vehicle.
With the "rear-end impact" on the traffic jam keep to safe distance.
With foreseeable longer waiting periods put down engine, in tunnels immediately.
Not brake while approximating and passing secure scenes of the accident.
On highways a rescue lane is to be released in the traffic jam in Germany, Austria, Czechia and Hungary in the middle of two lanes, with 3 or mehrstreifigen roadways is regulated nationwide differently between which lanes the rescue lane must be formed. Blocked a vehicle the hard shoulder, approx. 4 metres leave before and behind the obstacle in the right lane a gap. In Switzerland and in Slovenia the education of such a lane is expressly recommended.

With still fluent traffic any column jumping should be omitted. The hard shoulder may be used only on police instruction as a lane (to reach possibly around to the next motorway exit). In special cases (e.g., A99 ring Munich or A1 Morges-Ecublens) the state stripe or breakdown lane can be released by suitable sign-posting for the traffic.

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