City highway
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A city motorway is a motorway or expressway that runs within a locality and is mainly used by urban traffic.
Structural features
Urban highways differ from interurban highways in several ways. The connection points are smaller due to the limited space and are often equipped with parallel ramps. In addition, the distance between the connection points is much shorter than outside of built-up areas, which is why they are not announced on large signs 1000 meters in advance, as outside built-up areas, but usually only shortly beforehand and on smaller signs adapted to the cramped conditions. Due to the large number of crossing or crossing traffic routes (railways, roads and footpaths), the number of bridge structures is very high, and the city motorway is often equipped with street lighting . The heavy traffic load on urban motorways requires traffic control measures, so that a large number of traffic control and control systems are used there.
Since city highways often run through densely populated areas, residents are particularly annoyed by noise, dust and exhaust fumes. To protect residents from these influences, in addition to speed restrictions, structural protective measures such as noise barriers , open-pored road surfaces or enclosures are set up on city motorways . In many places, city highways are also routed as elevated roads or in a tunnel .
development
The model for the construction of city highways was the guiding principle of the car-friendly city . Vehicle traffic should therefore be able to flow unhindered and be clearly separated from other types of traffic. In the United States in particular, these ideas were quickly implemented and various city highways were built. In the 1950s and 1960s, urban highways were increasingly being planned and built in Europe. In war-torn Germany, many cities offered the opportunity to build city highways without having to demolish large areas (possibly causing conflict). Due to increasing motorization, the existing inner-city road network was overloaded in many places.
In many cases, induced traffic (see Jevons' Paradox ) did not have the hoped-for effect on the flow of traffic, or only for a short time, so that some city highways were extended or supplemented by additional expressways shortly after their opening. The first city motorway in West Germany was inaugurated on May 27, 1957 in Duisburg under the name Nord-Süd-Straße .
Inner-city motorways have disadvantages such as large space requirements, the fragmentation of city districts and the generation of noise and exhaust fumes. For some years now, city highways have been torn down or dismantled around the world. Only in Asia are in many megacities freeways built continue because often the here public transport is not sufficiently available.
