Traffic Impact Numbers (TINs)

Note

This page details forms and layers available in the new PMS UI from version 4.6 onwards.

Overview

The TINs module is used to assign TIN values to sections of the road network, either as stretches or by zone. TINs rank the road network according to its importance as a strategic traffic route.

The Speed Limits module in PMS consists of the following forms:

The following map layers are available (through the UI and also by WFS/WMS):

  • Latest TIN Values - this layer combines all TIN surveys calculating the latest TIN for a stretch of road using its creation date

  • TIN Surveys Layer and Grids - this layer shows each of the individual TIN surveys created by users

TIN Values

  • 0: No ranking assigned

  • 1: Low Impact – usually all day work permitted.

  • 2: Medium Impact – usually some restrictions such as at school opening or closing times.

  • 3: Medium Impact – usually restrictions at peak hours on weekdays.

  • 4: High Impact – usually daytime restrictions on weekdays.

  • 5: High Impact – usually daytime restrictions and peak hours restrictions on weekends.

Background

From section 4.5.1 of the Purple Book):

Road Authorities/ NRA, particularly in urban areas, may rank the road network according to its importance as a strategic traffic route by assigning it a Traffic Impact Number. This ranking, if used, is attached to the road inventory data and is visible through the MapRoad Roadworks Licensing (MRL) system. The Traffic Impact Number is set having regard to the need to minimise the disruption to traffic caused by nonemergency roadworks

Until MapRoad PMS v4.5, the TIN is associated with the road segment in its entirety. However this did not give enough scope to assign a higher TIN to a section of road at a location of significance in terms of the impact of an excavation.

Consideration was given to instructing the road schedule editor to subdivide such road segments into smaller units. This subdivision is ultimately constrained by the edges (junction to junction) as defined in the OSI Prime 2 spatial database. However this was ruled out as it may not give a small enough unit (“stretch”) to define the appropriate location of higher (or lower) impact.

As part of the 4.6 Release tools were created to allow TIN surveys to be created for any stretch of road network.

All of the existing TINS have been converted to the new database format for recording information. Effectively the linear reference will be for the entire length of the Edges that make up the road segment