Network planning is closely related to land use planning and, in fact, tends to follow it. The proper location and mix of land uses determines to a large extent the efficiency of urban
20 Geometric design of roads handbook
areas in the sense of their ‘liveability’. In short, are they such that people would wish to live, work and play there? This addresses many issues such as
• The noise generated by passing traffic
• The pollution of the air by vehicular exhaust emissions
• The safety of people, particularly children, when within or in close proximity to roads • Rat-running of commuters bypassing congested arterials by finding routes through
adjacent residential areas
The accessibility of areas is an important aspect of liveability, particularly in the sense of journey times, especially commuter travel times, and ease of use of the network. It has long been realised that the provision of additional infrastructure as a means of reducing conges- tion is simply not effective and that it is necessary to have planning policies supportive of public transport. To illustrate: A bus that transports up to 80 or more passengers occupies significantly less space than the equivalent 60 or more passenger cars required to transport them and hence contributes to a far lesser extent to congestion. Unfortunately, public trans- port cannot easily match the convenience of a passenger car in terms of availability, comfort and freedom of route selection. Strategies to make public transport more attractive to com- muters are discussed in Chapter 15. These include the sale of tickets at stations as opposed to buying them from the bus driver, and through ticketing in addition to the formulation of policies relating to the planning of the network and design of the buses.
Planning is concerned with broad regional issues where town and regional planners and the local communities play a role in ensuring that the links in the road network actually serve the communities through which they pass. Policy decisions are captured in a set of principles that define the manner in which a Transportation Department relates to other government departments, local land owners and communities to properly manage the net- work that forms their remit.
Policy requires that planning be initiated by an in-depth analysis of the needs of the inhabitants of the area through which the road is intended to pass. Furthermore, the policy usually will dictate that this analysis includes involvement of the communities concerned. This will lead to the definition of a corridor that respects community values and sensitivi- ties. For example, locating a road through a cemetery should only be the absolute last resort before all other alternatives have been investigated and rejected.
The government departments with which Transportation Department interacts in the planning of networks are mainly those at all levels of government with a brief addressing some or other aspect of the environment or service to communities. These include
• Land use including township development, farming activities and mining
• Environmental planning, including provision for migrating animals and avoidance of habitat fragmentation, game farms and timber plantations, and also control of riverine and air pollution
• Water supply including provision of dams and reservoirs, water purification, and pota- ble water reticulation
• Telecommunications, principally the location and use of land lines and cable TV • Power supply including the location of and horizontal and vertical clearances to over-
head power lines and space for transformers and substations • Provision of gas usually in underground pipes
• Waste management and sewerage, normally the purview of local authorities
• Other transport authorities such as those responsible for railways, airports, sea ports and lakes and canals
Policy 21
In short, government policy requires that roads not be planned in isolation from the requirements of other authorities. Interactions between them are often formulated in legisla- tion as the ultimate form of policy declaration.
Some interactions relate to utilities that are located within the road reserve as listed ear- lier, pointing out that service providers need to obtain the approval of the Transportation Authority as formulated in way-leaves prior to building their infrastructure.
It is necessary to have policies that define precisely where in the road reserve these utili- ties may be located. For example, foul water sewers and potable water reticulation are often installed on opposite sides of the road, with the sewers also normally being buried deeper than the fresh water supplies. This is to minimise the risk of the health hazard from pollution. No road authority is normally prepared to countenance a utility located under the road way itself. Furthermore, any underground crossing of the road is required to be sleeved so that the owner of the utility can access it without having to dig a trench across the road.
A further feature of the regulations and policies whereby a Transportation Authority defines the acceptable location of utilities within its road reserve is that these utilities are permitted only at the pleasure of the Transportation Authority. In short, if, for any reason, a portion of an existing road has to be relocated and this relocation impacts on the location of a utility, the service provider would have to undertake the relocation of the utility at its own cost to a new position that also has the approval of the Transportation Authority. Obviously, the Transportation Authority will carefully consider its own future plans and requirements, for example, an anticipated need for future doubling of a road’s cross-section in granting approval of the proposed new location.
The location of utilities has been discussed in some depth because it is more likely to impact directly on the detail of geometric design whereas the other topics listed in the pre- ceding text are more in the nature of planning issues relating, for example, to
• Origin–destination matrices
• Trip generation and attraction factors • Transport economics
• The overall length of the network
A policy decision that is common to many transportation departments is that all road reserves should be fenced. This is a safety issue intended to restrict access to the road reserve to specific and carefully selected points, one of the aspects of access management in fact. In countries where the seasonal migration of wild life is common, it may, however, be considered desirable to leave the migration paths unfenced as an environmental issue. In defence of this decision, it is offered that migrating animals seldom move after dark and find grass more comfortable to sleep on than the road surface other than during periods of intense cold, when the road surface will often be warmer than the surrounding areas. Signage advising of the possible presence of migrating animals would be useful from a road safety aspect.