air quality assessment & management
Reference and User Manual
AirWare   On-line Reference Manual
  Release Level 7.0
  Revision Level beta
  Release Date 2015 03

Last modified on:   Saturday, 11-Jul-15 20:07 CEST

Line sources

Line sources represent street or road segments and hold their emission data. They are, in principle independent entities represented by polylines, i.e., which can be with unconnected segments or part of a topological road network as used by any traffic model such as EMME/s or VISUM.

A Line Source is a named OBJECT. If it is associated with a network, its position and geometry is supplied by that network; else, the coordinates of its start and end node are specified with the line source directly.

Line Source descriptions consists of the standard OBJECT header and META DATA. It is characterized by its position and length, and it is shown on the associated MAP.

The set of data/attributes that define the line source data structure consists of the (fixed) set of META DATA, common to all OBJECTS, and an open list of specific attributes. The latter can be added dynamically to the data structure and data base by referring to any variable or Descriptor (defined in the systems knowledge base) in the HTML TEMPLATE that defines the object display and eidtor.

The attributes of a line source controlled by the HTML TEMPLATE and the Knowledge base include:

  1. name, administrative designation (number or ID), road type, length, number of lanes [optional: surface, slope, road networklink, fleet composition link].
  2. symbolic georeference to a model domain;
  3. vehicle frequency total (with optional vehicle class specific values)
  4. average speed;
  5. Substance specific emissions in g/s/km.
  6. optional scaling factor and additive term for each pollutant.

Editing a line source

The line source data that can be defined interactively include:

  • Attributes: META data and descriptive attributes: they are entered directly in the respective fields (such as the source name; please note that to store the data entered directly, the entries must be submitted to the data base through the "save" button.) or through the DESCRIPTOR editor (here changes become directly effective through the "save" button in the pop-up editor interface).

  • Geometry: line source location and geometry: uses a separate pop-up dialog for geometry editing triggered with the "Geometry" button in the basic OBJECT interface. Please note that a mximum of 50 segments can be defined for any line source/polyline).
    Geometry editing is done over a "live" Google map, supporting panning and zoomin for the best resolution possible. The interface will show existing line sources in the current map window, so that new roads can be positioned accordingly. Switch to the edit mode with the line symbol, then create a polyline with repeated mouseclicks; terminate the line with a double click at the same location. The map window should redraw, use the 'save" button if necessary. After closing the edit window, reload the OBJECT page (new line source will be shown in RED, centered, and edit the emissions.
  • Emissions:emission data: uses a separate edit mode triggered by the button: "Emissions".
The emission estimationsd are based on traffic frequency (user defined or taken from a traffic (equilibrium) model), and fleet composition, and average speed, and an optional cold-start fraction. Related and auxiliary data sets include:
  • fleet composition
  • emission factors
  • temporal emission patterns (EEA/CAFE)

The button "Emissions" start a dialog that compiles the segment specific data from the user interactively, including the data bases to be used for fleet composition (a named OBJECT with its own editor tool and the emission factor data base. The Traffic generated pollutants covered by a line source is, in principle, open (user defined with the data structure of the emission factors used) but always includes:   NOx, SO2, CO, VOC, PM10, PM2.5.
The results from the estimation can be assigned to the current road segment, or all road segments of the same type/category.

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