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RAL – The new road types for rural roads

The Guidelines for the Construction of Rural Roads (RAL) form the basis for all planning and designs for the new construction as well as the conversion and extension of rural roads in the charge of the federal government.

Initial situation

In recent years, the regulations for the design of rural roads have been fundamentally revised. The regulations, previously divided sectorally into alignment (RAS-L), cross-section (RAS-Q) and junctions (RAS-K-1), were merged into an integrated guideline for the design of rural roads (RAL).

The separate treatment of the aspects of alignment, cross-section and junctions, as well as the wide range of selectable design speeds, proved to be unfavourable in practical implementation, as they led to a variety of road designs that was detrimental to road safety. Also, individual regulations were outdated due to current knowledge and driving dynamics models were no longer valid from today's perspective.

What has changed?

The new guidelines for the design of rural roads (RAL) aim to standardise the design of rural roads more strongly in the future. The aim is to ensure that road users behave in the same way in comparable situations. As a result, a higher degree of road safety can be expected, especially in interactions between different road users.

The basis for the intended standardisation of rural roads into a few road types is the definition of four design classes for rural roads (EKL). These design classes are primarily determined by the respective connection importance of the road in the network (expressed by the road category according to the Guidelines for Integrated Network Design, RIN). Taking into account the traffic demand (examination of a higher or lower-ranking EKL), the allocation of a design class for a stretch of road is finally determined.

The image shows a table of road categories Relationship between road category and the design class for rural roads (EKL)

In future, rural roads are to be designed differently depending on the design class. The greater the importance of the connection and the longer the associated travel distances, the more elaborate the design should be. The linking of the importance of the connection with the four design classes for rural roads takes into account the different requirements for the accessibility of public service locations. The graduated requirements for development quality, on the other hand, serve to protect the environment and ensure the economic use of financial resources.

The design and operational characteristics of each design class (curve radii, longitudinal gradients, rounding of crests and hollows, junctions, etc.) are selected in such a way that rural roads with a specific connecting function are designed as uniformly as possible ("standardised") so that they are clearly distinguishable from rural roads with other connecting functions and are thus recognisable. The clear differences in design and operational features are also intended to promote a driving style appropriate to the link significance at a uniform speed and thus contribute significantly to increasing road safety.

As a general rule, higher travel speeds (cruising speeds) should be possible on rural roads with high connection significance and the associated long travel distances than on rural roads with low connection significance. These higher speeds generally require wider cross-sections, generous routing and special safety measures at junctions. They also require special protection measures for non-motorised traffic.

The mixture of vehicles with different speeds creates overtaking needs. Overtaking is more frequent the longer the travel distances. However, overtaking involving the use of the oncoming traffic lane carries a high risk. They should therefore be avoided as far as possible, because mistakes in overtaking often lead to accidents with the most serious consequences. Therefore, it was necessary to develop different concepts for the satisfaction of overtaking needs for roads with different connection significance.

The specifications of the RAL on the design and operational characteristics for roads of a design class are based on the results of a large number of research projects carried out in the recent past by the Federal Highway Research Institute (BASt). Here, various solution approaches were tested in pilot trials in the road network and these trials were accompanied scientifically. For this purpose, entire sections of rural roads were redesigned with the assistance of the federal states in order to investigate the effects of the respective measures on driving behaviour and the occurrence of accidents. The measurements and observations were supplemented by surveys of road users on acceptance. Recommendations were derived from the combination of the individual results, which were discussed with representatives from science, industry and administration and finally formulated in accordance with the guidelines.

How can the road user recognise the respective road type?

The road user can "recognise" the individual design classes by the different longitudinal marking in the middle of the road. They can also "read" from the type of marking lines how the road ahead, including the junctions, will generally be designed and what driving behaviour is appropriate to overcome the different travel distances.

The new rural road types at a glance

Trunk roads - EKL 1

The graphic shows a road cross-section Source: FGSV

On trunk roads, road users should be able to cover long distances in reasonable time spans despite the often high traffic loads. Since these links are highly congested, this type of road is designed with three lanes throughout, whereby the middle lane is alternately available to one direction of traffic and the other as an overtaking lane. These overtaking lanes make it possible to overtake safely on almost half of the link without using the oncoming traffic lane, regardless of oncoming traffic.

The very elongated alignment is based on a high planning speed. The operation as motorways requires non-motorised traffic to be guided along separate routes. In order to avoid waiting times at junctions, the intersecting rural roads are routed without a plan and are designed similar to the junctions of motorways with exit and entry lanes. Conflicts with crossing traffic are thus ruled out. A wide "traffic-related central reservation" with green colouring, which is clearly visible to the road user, spatially separates the two directions of travel and makes this special type of trunk road clear to the road user.

The picture shows roads with different cross-sections Source: TU Dresden

Interregional roads - EKL 2

The graphic shows a road cross-section Source: FGSV

The distances travelled on interregional roads are also still high; they are also often subject to high traffic volumes. The need for overtaking is correspondingly high. To avoid the risk of overtaking, this type of rural road, which is basically two-lane, should have three-lane sections with overtaking lanes at regular intervals. In this way, safe overtaking possibilities can be created for about 20 % of one direction of travel. On the other hand, overtaking with the use of the oncoming traffic lane should be avoided in the two-lane sections for reasons of road safety. To this end, advance notice boards should inform road users of the distance to the next safe overtaking section. The two directions of traffic are separated by marked double lines (continuous or interrupted). These are designed as uninterrupted double lines where the use of the oncoming traffic lane for the purpose of overtaking is to be prohibited. The stretched line design is based on a relatively high planning speed. Intersections are preferably designed as level junctions in order to avoid crossing the through road. At least in the case of high traffic loads, the junctions are operated with traffic lights, this applies in particular to intersections. For safety reasons, cycle traffic should be guided on special lanes accompanying the road.

The picture shows roads with different cross-sections Source: BASt, right: Zeltner 2015

Regional road - EKL 3

The graphic shows a road cross-section Source: FGSV

On regional roads, the travel distances are mostly less than 50 km in length. The traffic loads vary in a wide range. These rural roads are designed as two-lane roads throughout and thus correspond to the usual image of rural roads. The two directions of travel are separated from each other by a simple marking in the middle of the carriageway. This is usually interrupted and, where there is a particular risk of overtaking due to insufficient visibility, it is designed as a continuous line. Since the line layout is adapted to the terrain, a lower planning speed can be selected, which protects the surroundings and saves construction costs. For reasons of traffic safety, uniform lane widths of 3.50 m and verges of 0.50 m are appropriate even if traffic loads are not high. Accident investigations show that driving and meeting with these dimensions are predominantly conflict-free.

The picture shows a rural road Source: Jährig/BASt

The level junctions in the course of these roads are only operated with traffic signals when traffic loads are high. Alternatively, roundabouts are increasingly being installed for safety reasons. Cycling traffic is guided on or next to the carriageway.

Local roads - EKL 4

The graphic shows a road cross-section Source: FGSV

Local roads are of little importance in the rural road network. The traffic load is therefore usually low. For reasons of landscaping and cost savings, the roads are designed to fit the terrain and the planning speed is therefore low. Due to the mostly very low traffic load, they are only so narrow for cost reasons that two vehicles can only pass each other at moderate speed. The narrow roadway does not allow the marking of two separate lanes by a centre marking. Encounters therefore require increased attention. To dampen speeds, the lane is not delimited by two unbroken lines marked at the outermost edge, as was previously the case, but is visually narrowed by two guidelines applied laterally at a constant distance from the edge. This moving of the marking away from the edge of the lane protects the road user from leaving the lane even in the case of minor driving errors, prevents premature soiling of the marking and protects the edges of the road from damage. At the same time, however, the lateral guidelines require increased attention in the event of an encounter with other vehicles. In the event of such an encounter, the motorist is supposed to drive over the lateral guidelines, which intuitively prompts him to slow down. The intersections are sparsely designed due to the low traffic load; traffic signals or roundabouts are generally not required. The roadway is used by agricultural and non-motorised traffic in addition to motor vehicle traffic. The narrow width of the roadway and the terrain-adapted alignment is reason for the traffic authorities to consider whether the maximum permissible speed on this type of road should be limited to 70 km/h.

The picture shows a rural road Source: TU Dresden

The new design principle underlying the Guidelines for the Construction of Rural Roads (RAL) of creating a few standardised and clearly distinguishable road types will, if consistently implemented in the existing rural road network, contribute in the long term to rural roads fulfilling their function in the future with significantly higher road safety than before. This design principle follows a path that has already been successfully followed in some neighbouring European countries.

Frequently asked questions

Do all rural roads have to be reconstructed due to the new design guidelines?

There is no obligation to rebuild existing rural roads. The new regulations are to be implemented gradually in the rural road network in the course of measures for the structural maintenance of the substance or in conversion and extension measures.

Does the green colouring in the middle of the road create two directional lanes?

No. The separation of the directions of travel is only achieved by a special form of marking, it is not usually constructed. In this respect, unless otherwise signposted, the maximum speed limit of 100 km/h prescribed in the Road Traffic Act for one-way rural roads continues to apply. In terms of traffic law, the white lane demarcation lines are decisive for the road user and may not be crossed. The green marking also indicates that the road is a continuous three-lane highway with constantly recurring overtaking sections and that the junctions are designed as interchanges, as is the case with motorways.

Do double centre markings have a different meaning than single markings?

No, the significance in terms of traffic law is the same. The double centre markings serve to recognise this type of rural road as an inter-regional road. They are a sign that additional lanes are provided at regular intervals for safe overtaking and that the junctions are usually signalled for safety reasons.

Should one drive with the right-hand tyres to the right of the side guidance lines on local roads?

No, motor vehicles should regularly drive within the lateral guidelines. The narrow area to the right of the guideline should only be used when necessary in the event of an encounter.

Should cyclists ride to the left or to the right of the side guidance lines on local roads?

On local roads, cyclists should ride to the left of the guideline and share the space with motor vehicles.