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ITN steep gradient attribution

Go to: steep gradient attribution

 

Steep gradient attribution complements the weights and width attribution. Along with determining routes that will allow users to avoid bridge strikes and narrow gaps, routes can now also be determined using steep gradient information. Figure 1 illustrates how gradient information is linked to other features in the data model for OS MasterMap® Integrated Transport Network™ Layer (ITN).

Steep gradient data is supplied on written request to existing ITN Road Network with RRI customers as a separate CSV file.
Please note this is a frozen dataset which uses the December 2009 data.

Figure 1: ITN data model with gradient information

This gradient data has been merged into one of two categories depending on the value:

  • 14%–20% (1:7 – 1:5) gradients are within the Steep Gradient category
  • 20%+ (1:5 or steeper) gradients are within the Very Steep Gradient category

The steep gradients are captured as single point feature along a road at the steepest part of the road. All ITN steep gradients are captured in an uphill direction. Please see figure 3.

The steep gradient attribute is captured from one or both of the following sources:

  • By signage: a steep gradient position is captured at the steepest part of the gradient where signage has been identified. Figures 2 and 3 illustrate this situation.
  • By surveyor: a surveyor has visited the location and obtained a gradient value by taking at least three readings, approximately five metres apart, with a gradient level on what the surveyor considered to be the steepest part of the road on a hill.

Figure 2: The position of a steep gradient attribute

Figure 3: The orientation of the gradient (in this example +) relates to the direction of digitisation of the RoadLink to indicate which direction is uphill on a steep gradient

 

Steep gradient attribution

columnName

Variable

Comments

ID

Integer

Unique identifier

descriptiveGroup

Char(25)

‘Road Routing Information’

environmentQualifier (classification)

Char(25)

‘Steep Gradient Up’, ‘Very Steep Gradient Up’

orientation

Char(1)

+/-

refToRoadLink

Char(20)

Prefixed by 'osgb' then TOID

roadName

Char(50)

 

xCoord

Decimal (11,3)

Captured to three decimal places

yCoord

Decimal (11,3)

Captured to three decimal places

In this section:

ITN Technical specification – home

Purpose of this specification

ITN network features

ITN data structure

Overview of ITN themes

ITN Road Network theme

ITN Road Routing Information (RRI) theme

ITN Urban Paths theme

ITN Path Routing Information (PRI) theme

ITN Layer qualifiers

Feature types and attribution in the Road Network theme

Feature types and attribution in the Road Routing Information theme

Feature types and attribution in the Urban Paths Network theme

Feature types and attribution in the Path Routing Information theme

Descriptions of ITN Layer attributes

Attribution checklists for the Road Network and Urban Paths Network themes

ITN attribute definitions and values

ITN GML output format

ITN Layer GML examples

ITN character set

ITN weights and width attribution

ITN steep gradient attribution

This web page is part of the technical specification for OS MasterMap® Integrated Transport Network™ Layer. For the terms that apply to use of this specification, refer to Purpose of this specification.

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