8 Annex C: Operating Environment Classification

8.1  Introduction

The purpose of this annex is to provide guidance on the classification of a road network into operating environments on the basis of three criteria:

  • Physical characteristics – Motorways, Other roads
  • Network typology or traffic management orientation – Corridor, Network, Link or Critical spot
  • Traffic characteristics – Traffic flow and road safety situations (with optional additions) The basic steps in carrying out the classification are summarised below.
Establish a task force
The first step in the process is to establish a task force (recommended 2-4 people) within the relevant road operator organization to decide on which background information to use, which criteria for flow and safety to use etc. This operating environment classification document gives suggestions on how to accomplish this, including a range of threshold values that are recommended to be applied in order to ensure a harmonized approach.
Road network definition
The next step in the classification process is to decide on the extent of the road network concerned. This could be, for instance, the TEN-T Road Network under the road operator’s responsibility, with the addition of other key road network elements, interfaces to urban networks etc. The precise extension of the network is decided by the organisation carrying out the classification. All elements should be matched with a common and gapless map database.
Book resources needed for road network classification
According to earlier experiences, a “typical” national road operator’s road network will result in 200500 links.  2-3 experts are able to carry out the classification within a few (2-4) working days when preparations (the previous steps) have been made.
Classification is made through a link-by-link (from one exit/major junction to another exit/major junction) analysis supported by a dedicated Exceltool. By defining the value of the three criteria (above), the tool will provide the resulting Operating Environment in the Excel table.

8.2 Understanding the classification criteria and attributes

This chapter describes the attributes used for classification of Operating Environments.

8.2.1 Physical characteristics

One of the key elements in an Operating Environment is the physical layout of the road section itself. The road user is naturally well aware of the road, which he/she is using, and will base his/her expectancies on the ITS as well as other services on the road type. There are two basic types of roads with regard to the Operating Environments:

  • motorways: two or more lanes in both driving directions with separation of the carriageways of each direction, no at-grade intersections with other roads (intersections are handled by over- and underpasses with ramps)
  • all other roads than motorways; usually one or two driving lanes in each direction, no physical separation or a fence and/or barrier or without a barrier between driving directions, typically ground level intersections with other roads; in case of four-lane road, a dual carriageway road with separation of the two carriageways of two lanes each allowing also at-grade intersections.

Only lanes for motor vehicles (including dedicated bus lanes) are included in the counting of lanes. If there are more than two lanes in at least one of the driving directions, but it is not a case of being a motorway, the road should be classified among other roads than motorways. Hard shoulders should not be counted as lanes, even if used as temporary driving lanes.

In addition to the road types described above, the TEN-T (Trans-European Network – Transport) has some physically distinct sections, which set special requirements to road services including ITS. Such sections are:

  • tunnels, bridges, sections with reversible lanes, interchanges, junctions of restricted capacity between different basic types of roads other sections with exceptional characteristics. These types of infrastructure can be inserted in a general category of “critical spots” (see following section) where not only traffic problems may exist, but also special services have to be applied.
  • ferry connections within the road network. Even though the ferry connection parts are not likely to have the same ITS services as the surrounding road sections, for network continuity reasons the short ferry connection, which could be replaced by a bridge, should be given the same Operating Environment as the neighbouring road section(s). Longer ferry connections should be excluded.

8.2.2 Network typology or traffic management orientation

The road section concerned may also have a need for special service levels related to its role in the transport network. The roles important for the ITS service provision include:

  • corridor: the road section is part of a long corridor connecting major cities and other key locations such as major ports including in total at least two alternative routes, of which at least one usually is a motorway. An additional requirement of a corridor is that the network or road operator manages the corridor as such at least in some of their network operation plans and schemes; i.e. if the road sections of the corridor are managed and operated (totally) independently of one another (except for using the alternative route for detour during incidents), the road sections are treated as links and spots.
  • road/motorway network; grid of roads, motorways or a mix of roads and motorways. As above with corridors, the road sections in a network should be operated by traffic management and/or information tools as a network, and not only as totally independent elements. If the same road element is part of both a corridor and a network, the typology of road/motorway network is the recommended choice. 
  • peri-urban network; the road section is part of a motorway or road network integrating the TEN-T with the road/street network of major conurbations. Typically, a ring road round an urban area is a part of this kind of network. 
  • link: a road/motorway section connecting two locations (spot or a node of a network/road such as city, port, etc.) on the network while not constituting a part of a corridor or road/motorway nor peri-urban network in the traffic management sense. A location separating two links is sometimes an intersection or any other place on the road/motorway, where the characteristics of the road/motorway change in such a way that the Operating Environment or its attributes will also change. This can happen for instance if the traffic volume suddenly increases or decreases drastically at an intersection, the road climate changes abruptly, etc.  
  • spot (or short stretch); a specific part of the road/motorway differing from the surrounding part of the road network (critical bends, uphill sections, tunnels, bridges, interchanges etc.) especially with regard to the need of specific ITS solutions. Note that all bends, uphill sections, tunnels, bridges, interchanges etc. do not need to be classified as spots if they are not considered as a specific problem location.

This typology is a basis for defining Operating Environments and assigning a letter code to each type. Traffic flows and safety (see next points) will provide further details (distinguished with numbers).

Note: that any section of the road/motorway can only belong to one typology. This is to ensure the summing up of the network lengths based on the Operating Environments.

8.2.3 Traffic flow impact

Note that both for traffic flow impact and safety concerns, the road section is treated as a whole, consisting of both driving directions, even though in some cases the conditions might vary from one direction to the other. Again, this is done to ensure correct summing up of network lengths. If, however, a road operator insists on treating the directions as separate, this is allowed as long as this treatment is carried out consistently in the whole network of the country in question and specifically reported.  

The existence of traffic flow impact is related to the actual flow situation on the specific road section in terms of traffic volumes.

It is quite obvious that ITS service levels need to be linked to the volume of traffic and how it varies with time. We aim at specific quantitative thresholds for annual average daily traffic (AADT) to set up the categories for traffic flow impact. This is described accordingly:

  • daily traffic related impact; recurring congestion problems can affect traffic almost each working day, and incidents may also be quite frequent. If AADT is on motorways at least 12,500 vehicles/day per lane (i.e. 50,000 on 2+2, and 75,000 on 3+3 lane motorway) and on other roads at least 9,000 vehicles/day per lane (i.e. 18,000 on a 1+1 and 36,000 on a 2+2 lane road), the road should always be in this category.  If the number of lanes changes within the section, the lower lane number should be used when applying the traffic volume thresholds above.
  • seasonal traffic related impact; severe traffic congestion can exist but only seasonally, for instance during weekends during vacation times and holidays. Note that the current Operating Environments do not explicitly address seasonal problems on motorway links. If such, however, exist, these roads should be included in the Operating Environments with daily problems.
  • no traffic related impact; congestion and other flow-related problems are infrequent and are usually caused only by major incidents or events. If AADT is on motorways less than 6,000 vehicles/day per lane (i.e. 24,000 on 2+2, and 36,000 on 3+3 lane motorway) and on other roads less than 4,000 vehicles/day per lane (i.e. 8,000 on a 1+1 and 16,000 on a 2+2 lane road), the road should always be in this category.  

Note that the thresholds above leave room for member states and road operators to use their own thresholds set according to national or road operator’s own criteria. Naturally, local circumstances can also motivate deviation from the general principles and thresholds for specific road segments.

8.2.4 Potential road safety concerns

The existence of potential road safety concerns is related to the actual situation on the specific road section.

Two safety categories are to be used:

  • potential safety concerns; accident rates are considered high or severe outcomes are expected from any crashes; this can be due to e.g. severe weather problems related to snow, ice, fog and/ or strong cross-winds affect traffic considerably and frequently – especially in the wintertime. Other reasons for this classification may be high percentage of heavy traffic, existence of vulnerable road users at the road side, risk of severe consequences on isolated mountain roads, old fashioned or inadequate road design, etc. 
  • no major safety related concerns; problems considerably affecting road safety are only occasional and infrequent. 

There are three methods used to identify a section with potential safety concerns:

  1. Road sections, where the long-term (preferable at least five-year average) severe accident rate (accidents/100 million veh-km) is 30% higher than the national average, 
  2. Road sections, where the long-term fatality density (fatalities/100 road-km) is 30% higher than the national average, and 
  3. Road sections, where the EuroRAP rating is less than 3 stars (in scale 1-5).

The first method is recommended as the one most closely related to the safety experienced by the driver. Naturally, local circumstances can motivate deviation from the afore-mentioned methods and thresholds for specific road segments.

8.2.5 Other attributes

The actual Operating Environments are determined on the basis of the attributes listed above. In addition to these, the road operators may also voluntarily choose to use additional criteria for classifying their road network. Such additional attributes are most likely related to weather, environmental and heavy goods transport concerns. These attributes are elaborated upon below.

No agreement on the method for classification of these other attributes has been reached so far. Existence of weather problems

The road/motorway is classified as having critical weather-related problems, if severe weather problems related to snow, ice, fog, heavy rainfall and/or strong cross-winds considerably and frequently affect traffic – especially in the wintertime. Existence of environmental concerns

The road/motorway section has critical environment concerns if it is passing through an area sensitive to environmental (pollution, noise) impact or affected by regulations such as groundwater areas, parks, residential areas, schools, playgrounds, etc. Truck transport relevance

The link, corridor or network is of particular importance for freight transport. The proportion of heavy goods vehicles of all traffic or the average daily number of heavy goods vehicles are regarded as high by the road operator or the road/motorway is leading to a major logistics hub such as a port, airport (cargo), freight village etc.

8.3  Carrying out the classification in practice

8.3.1 Basic principles

This section describes how the road operators should classify their road networks into Operating Environments. The definition of what constitutes the network to be classified is decided by the road operator in question.

Note that if the road operator cannot classify a specific road section into any of the Operating

Environment categories given in the document, the partner should choose the Operating Environment best fitting the specific road section, and to inform the authors of this document of the characteristics of all such sections poorly fitting into the current Operating Environments. Such cases will be considered when future versions of the Operating Environments are being proposed and when this classification guidance is being updated. It should be noted that the ultimate goal is to achieve a consistent European methodology for classifying the road network into Operating Environments.

The classification method proposed takes into account the possibility of a later integration of the Operating Environment classification with a map-tool, allowing for network classification to be displayed in a map.

In practice, it seems to be easier to classify road networks into Operating Environments criteria by criteria, as often each criterion is best dealt with by a specific expert. A congestion expert can easily classify the network by traffic flow impact, whereas another expert on safety will quickly classify the whole network according to the existence of potential safety concerns.

The whole relevant road network is to be classified. For the classification, the network is to be divided into sections according to the basic factors determining the Operating Environment – physical layout, network typology, traffic flow impact and potential safety concerns as well as the additional attributes (weather, environment, freight), which the road operator chooses to use. This means that a new section could start each time, when the category of at least one of these factors and attributes changes. This may result in road sections of very varying length (from hundreds of metres to hundreds of kilometres). The road operators may also cut the sections also at other points, according to their own uses and preferences. The general recommendation is to use motorway exits and major road junctions as the points of division for the road network, because this will simplify some later procedures such as map-matching. Hence, a road section normally runs from one exit/ junction to another, but not necessarily the next one.

Naturally, road characteristics, traffic flow and road safety conditions evolve over time partly due to ITS deployments. Hence, the need to update the Operating Environment classification should be assessed at regular intervals.

8.3.2 Using the Excel support tool

An efficient way of carrying out the classification is to use an Excel tool for this. The road network is filled in into the Excel workbook road by road and motorway by motorway, section by section. All network elements classified should include official names (junction names, road names and/or TMC location codes if available) since this simplifies the matching of elements for various applications and supports error detection and quality management in general. The worksheet has the following columns:

  • Identification number of the road network element (e.g. reference to a map element to be introduced in an optional folder or sheet; to make the numbering unique, nation codes such as DE, FI, SE etc. are recommended to precede the actual numbers)
  • Name of road/motorway (e.g. E18, according to the member state naming convention)
  • Start of section (distance from start of road/coordinate/location description)
  • End of section (distance from start of road/coordinate/location description)
  • Length of section (km, 0-3 decimals)
  • Physical characteristics, 
  • Network typology or traffic management orientation
  • Existence of potential safety concerns (0=no, 1=yes)
  • Existence of traffic impact (0=no, 1=seasonal, 2=daily)
  • Existence of weather problems (0=no, 1=yes); W (optional)
  • Existence of environmental concerns (0=no, 1=yes); E (optional)
  • Truck relevance (0=no, 1=yes); T (optional)
  • Operating Environment: this is automatically determined through a macro utilising the combination of physical layout, typology and existence of traffic flow and safety concerns and to be accompanied with the weather, environment and truck relevance attributes

The other columns of the worksheet can be used for describing the coverage (%) of the road/ motorway section with different core ITS services of specific service levels, or e.g. the values of the deployment indicators during a year or a project phase. The excel sheet can also be used as direct input to a map or other ways of reporting the classification. 

The empty Excel worksheet for the classification is presented in Figure C-1. An example of a filled excel sheet is given in Figure C-2.

Figure C-1: A screenshot of the excel worksheet for classification of road network into  Operating Environments
Figure C-2: Example of the contents of the excel worksheet for classification of road  network into Operating Environments. Note that for map use, the start and the end points should be indicated by specific map attributes such as e.g. coordinates.

Reporting the classification

There are two main ways to report the classification in addition to the use of the Excel document as the final outcome. The target should be to connect the report directly to the classification of the Operating Environments either in the Excel tool so that the reports are more or less automatically generated after the data from the road network has been properly filled in. 

The first way of reporting is to use a map and geographic information system (GIS). The choice of the mapping software should comply with the mapping requirements of the overall deployment monitoring and reporting requirements related to the ongoing situation of the road operator.

The second way is to report the lengths of each Operating Environment, and this can be carried out on the basis of the Excel worksheet. This is useful for the deployment target setting and deployment monitoring purposes. An example is given in Table C-1 below.

Figure C-1: A screenshot of the excel worksheet for classification of road network into  Operating Environments.

It is also essential that the road operator describes in detail how they have made the classification into Operating Environments, if their own method of classification differs from the one proposed in these guidelines. This is crucial as the ultimate goal is to arrive at a common and consistent classification in Europe. In order to reach a consensus, it is essential that all involved understand the routines and cultures applied by each partner and their reasons for such ways of applications.

If the classification is reported with another map tool, the same colours should be used in the map tools utilised. These colours are the standard HTML colours indicated in Figure C-2.

Table C-2: The colour scheme to be used for the Operating Environments in the maps