1.12.1 National and Trans-National
The demands of legislation can greatly influence the design and management of a road in order to control its influence on the water environment. General legislation, such as European directives (e. g. the Water Framework Directive), define water protection in a general manner with universal requirements that no pollutant input is allowed and that high cleanliness of water bodies should be established. However valid legislation at a national level, or even locally valid ordinances, can precisely define such requirements in terms of the level and manner of these protection measures. The level of the protective prescriptions depends on the legal system. In some countries the valid legislation is very general repeating obligations from the European directives and the proper implementation and then the functioning of protection measures are the responsibility of the road owner, operator and the designer. In some other cases, protection is very precisely defined by technical legislation that has been mandated centrally. In these kinds of document all the technical details can be found.
During the development of a road scheme, existing hydrological and hydrogeological zones, crossed by road, are classified on the basis of legally existing water protection zones (e. g. drinking water source protection zones, Natura 2000 zones) and natural field conditions encountered. As a first step, desk studies are performed to define the demands and requirements for each section of the road consequent upon the legislation. Similar sections are then grouped together and field investigations undertaken to gather representative information on each group. Results of the field investigations are used to determine the specific level of water protection that is required. If the particular requirements defined in any existing protection ordinances are not as strict as those obtained as a consequence of the investigations performed during the scheme development, technical protection measurements must be adopted to ensure that the water body is protected according to the natural conditions that have now been revealed. If prescribed demands in the ordinances are stricter than established by field investigations, the protection requirements are retained and usually the designer does not oppose them. The designer would need to be certain that every section within the group of sections being analysed was less susceptible to degradation. Even then, the time taken to get the water protection zones re-classified to a lower risk category will often be longer than the time taken to commence construction, negating the benefit that might otherwise accrue to the road scheme.
Among locally — and state-valid legislation, constraints to road construction and operation are usually defined in ordinances defining drinking water source protection zones. They are defined as requirements, prohibitions and restrictions and they can be grouped in the following way:
• restrictions on areas for construction of roads and manoeuvring areas;
• technical engineering requirements for the protection of groundwater (e. g. runoff collection / safety bunds / soakaways / pipe integrity);
• traffic speed restrictions, restrictions of certain traffic types;
• management control measures (e. g. cleanliness of drainage facilities, controlled disposal of plant cuttings, periodic water sampling, etc.);
• restrictions of transport of certain dangerous and harmful substances; and
• demands regarding the setting up of road signs in protected areas.
