KEY ASPECTS OF NAVIGATION - Net 2 Class 11. # 2 Net 2 Class - Definition Net 2 Class (N2C) is a...

KEY ASPECTS OF NAVIGATION- Net 2 Class

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Net 2 Class - Definition

Net 2 Class (N2C) is a classification system for roads and ferries based on the importance that the roads and ferries have in the totalroad network.

Net 2 Class differs functionally from FRC:

Most customers use FRCs for display purposes to show the real world value of a road (i.e. a US Hwy vs. a State Hwy).

Net 2 Class shows the routing importance of a road (inclusive of shortcuts, for example, that may not have a route number).

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There are seven Net 2 Class values:

Value Definition

1 Roads of International Importance

2 Roads of National Importance

3 Roads of Regional Importance

4 Local Roads of High Importance

5 Local Roads

6 Local Roads of Minor Importance

7 All Restricted Roads

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Class 1: Roads of international importanceClass 1: Roads of international importance

All Road Elements and Ferry Connections representing roads and ferries of high importance, which are part of a connection used for international andnational traffic and transport:

most important roads and ferries for through traffic which connect the most important municipalities of the country and of the neighboring countries.

generally, but not necessarily, this includes freeways (interstates).- But not all freeways must belong to this class.

Value Definition





5 Local Roads



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Class 1: Roads of international importanceClass 1: Roads of international importance

serves a connectivity function.

often a major ring road (interstate loop going around the perimeter of a metropolitan area).

can run through city or lead into/out of a city.

dependent on incoming roads.

Value Definition





5 Local Roads



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All Road Elements and Ferry Connections representing roads and ferries used to travel between neighboring parts of a country and of neighboring countries.

– important roads and ferries for through traffic used to travel within the country

– important main roads running parallel to freeways that are part of N2C 1 and which are used when those freeways cannot be part of a route calculation

Class 2: Roads of national importanceClass 2: Roads of national importance

Value Definition





5 Local Roads



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Class 2: Roads of national importanceClass 2: Roads of national importance

serves a connectivity function.

often a ring road (often a 3-digit interstate loop) – NOTE: Ring roads inside another ring road formed by N2C 2 cannot have N2C 1

value.

can run through city or lead into/out of a city.

dependent on incoming roads.

Value Definition





5 Local Roads



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All Road Elements and Ferry Connections representing most important roads for through traffic used to travel between different regions of the country.

– roads making settlements accessible

– roads making different parts of a settlement accessible

– main connections within a settlement

– main connecting roads in rural environment

Class 3: Roads of regional importanceClass 3: Roads of regional importance

Value Definition





5 Local Roads



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Class 3: Roads of regional importanceClass 3: Roads of regional importance

roads connecting the different settlements of the urban area

sometimes a kind of inner ring road

roads connecting the inner ring road and the outer ring road

through traffic in the city

Value Definition





5 Local Roads



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All Road Elements and Ferry Connections representing roads making minor settlements accessible

– roads used to travel within a part of a settlement

– local roads of minor or non-connecting function in a rural area

– most important roads within a settlement (collecting roads)

Class 4: Local roads of high importanceClass 4: Local roads of high importance

Value Definition





5 Local Roads



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All Road Elements and Ferry Connections representing roads which only have a destination function.

– They are only used to reach a certain address or destination.

– This will be the most common N2C value in the database.

Class 5: Local roadsClass 5: Local roads

Value Definition





5 Local Roads



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All Road Elements and Ferry Connections representing local roads accessible for traffic but with minor function.

Examples:– unpaved roads or roads in bad condition which have no connectivity function, but

only a destination function

– all roads in 30 km/20 mph zones (in residential areas, but not if the road has an important connecting function). These would be roads like parking lots, alleys, etc.

The key to this classification is really road condition, speed limit and purpose. These are roads that are in bad shape, have speed limits 20 mph or below or are destination roads like alleys, driveways and parking lots.

Class 6: Local roads of minor importanceClass 6: Local roads of minor importance

Value Definition





5 Local Roads



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All Road Elements and Ferry Connections representing roads inaccessible for normal traffic.

Examples: – roads only accessible for residents – this would include roads within gated

communities.– roads inaccessible for normal cars– walkways or path ways– inaccessible pedestrian roads– roads only accessible for public transport– Continued on next slide…Continued on next slide…

Class 7: All restricted roadsClass 7: All restricted roads

Value Definition





5 Local Roads



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Private roads –• N2C 7 only includes private roads that receive a “Special Restriction”

classification as well (Members Only, Residents Only, Employees Only, Authorized Personnel Only or Restricted Access).

• Roads that receive the “Private” classification in the routing section of the Attrib tab, but do NOT qualify for a Special Restriction, are not classified as a restricted road in terms of Net 2 Class values. Those roads should receive a N2C value other than 7.

For this class, remember the phrase ‘inaccessible for normal traffic’.

Class 7: Class 7: All restricted roadsAll restricted roads

Value Definition





5 Local Roads



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Class 7: Private RoadsClass 7: Private Roads

Tompkins Ln PVTPrivate is indicated on the street sign, but no other “Residents Only”, “Keep Out”, etc. signs are present.

This would NOT be classified as This would NOT be classified as N2C 7; it should get a value other N2C 7; it should get a value other than 7 (whatever is appropriate for than 7 (whatever is appropriate for the road, probably a 5 or a 6).the road, probably a 5 or a 6).

Value Definition





5 Local Roads



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Tompkins Ln PVT

This would be classified as N2C 7; This would be classified as N2C 7; as well as receive the Restricted as well as receive the Restricted Access classification of “Residents Access classification of “Residents Only”.Only”.

Value Definition





5 Local Roads



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How do Private Roads fit into N2C?How do Private Roads fit into N2C?

– N2C 7 only includes private roads that receive a “Special Restriction” classification as well (Members Only, Residents Only, Employees Only, Authorized Personnel Only or Restricted Access).

– Roads that receive the “Private” classification on the Routing Flag (RF) tab, but do NOT qualify for a Special Restriction, are not classified as a restricted road in terms of Net 2 Class values. Those roads should receive a N2C value other than 7.

– Remember, Private Road attribution has to do with who owns and maintains the road, not who can drive on it.

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The one exception… residential gated communities MUST be classed

as “Resident Only” whether there’s an actual sign in reality or not.

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Net 2 Class – FRC Equivalent Chart

This FRC Equivalent chart should be used as merely a guidelineguideline in assigning Net 2 class values.

The rules outlined in this presentation (and described in detail in SDS 9.0, Section 2.18), should be followed when applying Net 2 class values.

The logical attribution of Net 2 Class value based upon the Net 2 Class value of connecting roads should take precedence over using the direct translation of the chart.

FRC-A Net 2 Class

1 1

2 2

3 2

4 3

5.1 3

5.2 4

6s 7s that are dead-ends

5

6 & 7’s in poor condition, speed limit of 20 mph, parking lots or driveways

6

8s and all restricted roads 7

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Net 2 Class - Connectivity

Net 2 Class must follow downwards excluding rules:Net 2 Class must follow downwards excluding rules:

Downwards excluding is an important implementation of closed network, making sure that a network is properly closed and that connections between the different classifications are ensured.

Downwards excluding describes how the road classification shall be captured for a location with a connecting potential: namely connectors, roundabouts, crossings, interchanges, parallel roads and slip roads.

If Road Elements with the lower classes are excluded, the Road Elements with the higher classes have to form a closed network and all connections for traffic flow shall be assured.

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Closed network:

The four most important Net 2 Class values (1 – 4) shall each form a closed network together with the more important Net 2 Class(es).

– This is similar to the closed network required for FRC 1 – 6.

Each Road Element and Ferry Connection, having a Net 2 Class of 1-4, shall be connected at both sides by another Road Element or Ferry Connection with the same or higher Net 2 Class.

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Closed Network:Closed Network:

Net 2 Class represents a classification of 7 networks of roads and ferries, whicheach forms a closed network together with the higher Net 2 Class(es).

This means that: each captured Road Element and Ferry Connection with a certain Net 2 Class must be

connected at least at one side by another captured Road Element and Ferry Connection with the same or a higher Net 2 Class.

A network is called closed if there exists at least one path from every chain in the network to every other chain in this network.

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The four highest Net 2 Class values must form a closednetwork.

Note how 4’s end at 4’s or higher, 3’s end at 3’s or higher,etc.

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Rule:Rule: Two roads running more or less parallel and connecting the same settlements shall not have the same Net 2 Class:– The fastest connection shall be identified

as more important, and thus will receive the higher Net 2 Class value.

Notice how the parallelnorth/south roads herehave different Net 2 Classvalues; based onimportance of the road tonavigation.

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Rule: Rule: Ring roads and by-passes collect local and connecting traffic and shall have a higher Net 2 Class than roads going through the center.

A prime example of this are 3-digit interstate loops & bypasses, but it can apply to lower Net 2 Class roads as well.

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Rule: Rule: All relevant connections between high Net 2 Class roads shall receive the Net 2 Class necessary to ensure connectivity between them.

This is the closed network concept.

See next slide for more info….

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Closed network:

These Traffic restrictions are are taken into account when considering N2C connectivity:

– Direction of Traffic Flow for Road or Ferry– Prohibited Maneuver– Restricted Maneuver– Implicit Turn

So if one of these traffic restrictions does NOT allow a certain path, Net 2 Class values may need to be upgraded on connecting roads to maintain a closed graph.

See the next slide for an example….

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Closed network rules: Graveyards, factories and -in general- functional dead ends may not

appear. Functional dead ends are only allowed when continuity is ensured.

This would be a functional dead end for the Net 2 class due to the DTRF, so another road must be “upgraded” to keep the closed graph.

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Closed network rules: Prohibited and Restricted Maneuvers shall not be taken into account to

close the network at crossings where the maneuvers are intended to force the usage of Small and Small/Major Slip Roads.

This is truly a dead-end for the N2C 2. Not allowed!

This functional dead end is allowed here, because there’s a slip road with the higher N2C that keeps the network closed.

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Net 2 Class - Roundabouts

Roundabouts:Roundabouts:Net 2 Class of Road Elements representing a roundabout is the same as thehighest Net 2 Class of the Road Elements which join the Roundabout.

This is the same as the rule for FRC.

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Net 2 Class - Connectors

Crossings and connectors:Crossings and connectors:The Net 2 Class of a connector depends on its function and on the Net 2 classesof the roads making use of the connector.

Internal (isolated) connectors:Internal (isolated) connectors: If a connector has the function of only connecting

the carriageways of a multi carriageway (isolated connector), then it shall have the same Net 2 Class as the multi carriageway.

This is the same rule as for FRC.

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Crossings:Crossings: To ensure complete connectivity, the Net 2 Class of the four connectors of a

crossing of two multi carriageways is equal to the highest Net 2 Class of the multi carriageways, in case the most important Net 2 Class makes a bend.


Connectors involved in connecting the roads with the highest Net 2 Class.


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Crossings:Crossings: In other cases, the connector shall have the highest Net 2 Class that is

necessary to ensure connectivity. The Net 2 Class of the carriageways of the multi carriageways is not taken

into account.


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Crossings:Crossings: If a connector ensures connectivity with Road Elements representing path

ways, stairs or a pedestrian tunnel or bridge and the connector can be used to make U-turns on the multi carriageway, Net 2 Class related to the connector is the same as the Net 2 Class related to the multi carriageway.


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Crossings:Crossings: In case the connector is mainly designed to

perform a U-turn, meant to ensure connectivity between two intersecting roads, the connector shall get the road class of the Dual Carriageway, even when connector is ensuring connectivity with another intersecting road with a lower class.

– E.g. a Michigan U-turn that is also used for other connections.


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The Road Element(s) representing the Small Slip Road will have the lowest Net 2 Class value of the Road Elements for which it is intended to serve as smooth connection.


Small Slip Roads and Small/Major Slip Roads at interchanges:Small Slip Roads and Small/Major Slip Roads at interchanges:

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Net 2 Class – Major Slip Roads

Major Slip Roads:Major Slip Roads:

Net 2 Class of a Road Element representing a major Slip Road is based on the Net 2 Class of the captured Road Elements, which are connected by the major Slip Road.

The Road Element representing the slip road will have the same Net 2 Class as the second highest Net 2 Class related to the Road Elements representing the main roads, which are connected by the slip road.

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Major Slip Roads at interchanges:Major Slip Roads at interchanges:

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Net 2 Class – Freeway Intersections

The No Drop-Down Rule Applies:The No Drop-Down Rule Applies:

If an outgoing road has a higher or equal important Net 2 Class value than an incoming road, then the sequence of roads that connects the incoming with the outgoing road needs to be increased to match the outgoing road.

If an incoming road has a higher important Net 2 Class value than an outgoing road, then the sequence of roads that connects the incoming with the outgoing road should NOT be increased, but rather match the outgoing road.

Except in cases where a drop-down would occur…see next Except in cases where a drop-down would occur…see next slide…slide…

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This segment should be a Net 2 class of 2 until the ramp joins.

This would be a Net 2 Class error…the ramp drops from a value of 1 to 5, then back to 1 again…

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Net 2 Class – Parallel Roads

Parallel Roads:Parallel Roads:

The Net 2 Class of Road Elements representing a road running parallel to a motorway has the highest Net 2 Class, necessary to ensure connectivity between the roads it connects. This corresponds with the highest Net 2 Class of the Major Slip Roads connected to the parallel road.

The complete stretch of roads, which is regarded as one parallel road, does

in general have the same Net 2 Class.

In exceptional cases, namely to avoid functional dead ends, one stretch can have different Net 2 Classes.

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Net 2 Class – Parallel Roads

Parallel Roads:Parallel Roads:

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Net 2 Class – Parking (FOW 8, 16 & 19)

Parking Geometry:Parking Geometry:

Road Elements with Form of Way ETA (Parking Area) and Entrance to /Exit From a Car Park, related to parking buildings shall have Net 2 Class 6.

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Net 2 Class – Roads under Construction

Roads under Construction:Roads under Construction:Net 2 Class related to a road under construction or a road on which long term works are located takes the Net 2 Class of the road that it will have when it is Opened..

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