EN 1991-2 defines models of traffic loads for the design of road bridges, footbridges and railway bridges. For the design of new bridges, EN 1991-2 is intended to be used, for direct application, together with Eurocodes EN 1990 to 1999.
The bases for combinations of traffic loads with non-traffic loads are given in EN 1990,A2.
Complementary rules may be specified for individual projects :
– when traffic loads need to be considered which are not defined in this Part of Eurocode 1 (e.g. site loads, military loads, tramway loads) ;
– for bridges intended for both road and rail traffic ;
– for actions to be considered in accidental design situations ;
– for masonry arch bridges.
For road bridges, Load Models 1 and 2, defined in 4.3.2 and 4.3.3, and taken into account with adjustment factors _ and _ equal to 1, are deemed to represent the most severe traffic met or expected in practice, other than that of special vehicles requiring permits to travel, on the main routes of European countries. The traffic on other routes in these countries and in some other countries may be substantially lighter, or better controlled. However it should be noted that a great number of existing bridges do not meet the requirements of this EN 1991-2 and the associated Structural Eurocodes EN 1992 to EN 1999.
It is therefore recommended to the national authorities that values of the adjustment factors _ and _ be chosen for road bridge design corresponding possibly to several classes of routes on which the bridges are located, but remain as few and simple as possible, based on consideration of the national traffic regulations and the efficiency of the associated control.
For railway bridges, Load Model 71 (together with Load Model SW/0 for continuous bridges), defined in 6.3.2, represent the static effect of standard rail traffic operating over the standard-gauge or wide-gauge European mainline-network. Load Model SW/2, defined in 6.3.3, represents the static effect of heavy rail traffic. The lines, or sections of lines, over which such loads shall be taken into account are defined in the National Annex (see below) or for the individual project.
Provision is made for varying the specified loading to cater for variations in the type, volume and maximum weight of rail traffic on different railways, as well as for different qualities of track. The characteristic values given for Load Models 71 and SW/0 may be multiplied by a factor _ for lines carrying rail traffic which is heavier or lighter than the standard.
In addition two other load models are given for railway bridges :
_ load model "unloaded train" for checking the lateral stability of single track bridges and
_ load model HSLM to represent the loading from passenger trains at speeds exceeding 200 km/h.
Guidance is also given on aerodynamic actions on structures adjacent to railway tracks as a result of passing trains and on other actions from railway infrastructure.
Bridges are essentially public works, for which :
– the European Directive 89/440/EEC on contracts for public works is particularly relevant, and
– public authorities have responsibilities as owners.
Public authorities may also have responsibilities for the issue of regulations on authorised traffic (especially on vehicle loads) and for delivery and control dispensations when relevant, e.g. for special vehicles.
EN 1991-2 is therefore intended for use by :
– committees drafting standards for structural design and related product, testing and execution standards ;
– clients (e.g. for the formulation of their specific requirements on traffic and associated loading requirements) ;
– designers and constructors ;
– relevant authorities.
Where a Table of a Figure are part of a NOTE, the Table or the Figure number is followed by (n) (e.g. Table 4.5(n)).
EN 1991-2 defines imposed loads (models and representative values) associated with road traffic, pedestrian actions and rail traffic which include, when relevant, dynamic effects and centrifugal, braking and acceleration actions and actions for accidental design situations.
Imposed loads defined in EN 1991-2 are intended to be used for the design of new bridges, including piers, abutments, upstand walls, wing walls and flank walls etc., and their foundations.
The load models and values given in EN 1991-2 should be used for the design of retaining walls adjacent to roads and railway lines.
EN 1991-2 is intended to be used in conjunction with EN 1990 (especially A2) and EN 1991 to EN 1999.
Section 1 gives definitions and symbols.
Section 2 defines loading principles for road bridges, footbridges (or cycle-track bridges) and railway bridges.
Section 3 is concerned with design situations and gives guidance on simultaneity of traffic load models and on combinations with non-traffic actions.
Section 4 defines :
– imposed loads (models and representative values) due to traffic actions on road bridges and their conditions of mutual combination and of combination with pedestrian and cycle traffic (see section 5) ;
– other actions specifically for the design of road bridges.
Section 5 defines :
– imposed loads (models and representative values) on footways, cycle tracks and footbridges ;
– other actions specifically for the design of footbridges.
Sections 4 and 5 also define loads transmitted to the structure by vehicle restraint systems and/or pedestrian parapets.
Section 6 defines :
– imposed actions due to rail traffic on bridges ;
– other actions specifically for the design of railway bridges and structures adjacent to the railway.
