Road network
The road network is the system of interconnected roads designed to accommodate wheeled road going vehicles and pedestrian traffic.
Contents
Description
The road network consists of a system of interconnected paved carriageways which are designed to carry buses, cars and goods vehicles; the road network generally forms the most basic level of transport infrastructure within urban areas, and will link with all other areas, both within and beyond the boundaries of the urban area.
A road network can be divided into parts such as:
- intersections
- controlled or uncontrolled intersections
- roundabouts
- urban roads
- rural roads
- motorways
- bicycle lanes
- footpaths and pedestrian areas
- pedestrian crossings
Furthermore, several road-side systems (or Intelligent Transportation Systems, ITS) and monitoring systems are used to control the traffic, such as
- intersection control with traffic lights
- Variable Message Signs (VMS)
- Dynamic Road Information Panels (DRIPs)
- loop detectors
Functions
Social
The road network facilitates the movement of people allowing for social interaction.
Economic
By connecting geographic locations, road networks facilitate the transport and movement of people, goods, and services, creating welfare. Road networks played a crucial role in the economic development of the 20th century, enabling relatively fast individual transportation for the masses from the second part of the 20th century[1]. And although the development of air transportation and telecommunication networks started to compete with road networks during the later part of the 20th century, in most EU countries road transport still plays a crucial role in the national and local transportation networks.
Investments in road networks reduce the travel time between two locations, increase the robustness of the transportation network and hence reduce the travel costs. These kind of effects are referred to as the so-called direct effects of road networks. The economic impact of road networks extend in most cases beyond these direct effects due to the further rounds of economic activity as a result of the efficient transportation of goods, skills and persons, the so-called indirect economic effects.
The investment in road networks do not just lead to positive effects. Apart from the necessary investments in terms of time and money, road networks fill up land and have negative social and environmental impacts such as congestion, traffic accidents, light and noise pollution and of course air pollution. In order to assess if an investment in a road network has a positive effect on society, or to compare different alternatives of transport infrastructure, economic tools can be used to value the positive and negative direct, indirect and external effects of these alternatives. The difficulty with this kind of economic appraisal is first of all, that it is not easy to measure the valuation of travel time[2],and secondly that new road infrastructure will generate road use that would not have been made without the investments, the so-called induced demand. A third problem is that especially external effects such as quality of life, the value of unique nature, the value of no air pollution, are very difficult to be expressed in monetary terms.
Although road networks are hardly affected by security threats (crime, terrorism), it can happen that roads get blocked due to e.g. riots, bomb explosions, traffic flow management, etc. The economic impact of these kind of threats can be significant, especially in indirect terms since roads facilitate economic activities. Security measures can prevent these negative economic effects, for instance, by ensuring there are alternatives routes for traffic (traffic flow management).
Mobility
The road network facilitates movement from one area to another, and has an important role to play in the urban environment.
Safety
Safety of road users is typically focused on road safety (prevention of accidents through speed control, seatbelt enforcement, etc).
Security Issues
The use of the road network is regarded as being safe, with the main threats to security coming from the possibility of vehicle theft or vandalism.
- Terrorist threats? (JP)
- Road blocks by rioters? (JP)
Measures
A highly visible police presence can limit the threats to safety and security.
- traffic flow management (JP)?
