Calculation

Find it here:

MOUS_ICO Menu: Noise > Calculation

In this dialog box, we create alternatives and perform calculations. Only one alternative may be calculated at a time.

An alternative may be regarded as a name of the calculation we are running. The calculation results and the input data that were current at the start of the calculations are saved together with the alternative. In Novapoint Noise, we may compare different alternatives by printing text at calculation points for multiple alternatives at the same time.

In Novapoint Noise, it is completely up to the user of the program to keep track of the different alternatives. The user himself must change input data as different alternatives are calculated.

We have the opportunity to supplement an alternative with more points. This is done by setting the calculated points passive and the new points active. After that, the calculation of the relevant alternative is restarted. In this case, as well it is the user's responsibility to make sure that input data for the two calculations are identical.

Alternative - This list gives an overview of all defined alternatives.

Object handling

New alternative - This gives us a small dialog box where we may specify a name for an alternative. By clicking OK in the dialog box, we return and the name of the new alternative is added to the list Alternative.
Delete - The alternative selected in the list is deleted and all results for this alternative are deleted as well. This option cannot be undone.
Change - Opens the same dialog box as for New alternative and gives the opportunity to change the name of the current alternative.
Calculate - Starts the calculation. Before starting the calculation of an alternative, all input data have to be correct. The calculation may be interrupted by pressing <Esc>.

Window handling

+ The height of the window in the dialog box showing the list of alternatives is increased.
- The height of the window in the dialog box showing the list of alternatives is decreased.

Status

Number - gives the total number of alternatives defined in Novapoint Noise.

Calculation parameters

Save details - If this is on during calculation, detailed information about the calculation is saved. Data for each profile between noise sources and calculation points are saved. The data is saved in files in a folder called TMP which is created as a subdirectory to where the AutoCAD drawing is stored. This may amount to a lot of files and the calculation will take more time with this option on. To get reports with detailed information (List separately for each road or All details), this option must be on during calculation.
Reuse of profiles - When a Novapoint Noise calculation starts, a separate terrain profile is generated for each combination of noise source and calculation point. The process of importing this information represents nearly 90 % of the total calculation time.

When Reuse of profiles is activated, all terrain profiles are saved to a file during the first calculation. For the following calculation(s), Novapoint Noise fetches the requested terrain profiles which already exist from the file. Requested profiles that do not exist in the file, are imported from the terrain model. These new terrain profiles are saved with the rest.

Terrain profiles that are saved to file, are deleted once the calculation starts if the terrain model has been accessed since the previous calculation. This is done to prevent mixing old and new terrain profiles in a Novapoint Noise calculation or using only old terrain profiles if there have been changes to the terrain model.

Changes of barriers, buildings, hard ground regions and traffic data may be made without regenerating new terrain profiles from the terrain model. This functionality reduces time use considerably.

This option can not be used if reflection is specified.

Storing terrain profiles may require a lot of disk space. The terrain profiles for one single calculation point may require approximately 50 kb per road. The exact number of bytes needed depends on the length of the road, the distance between the road and the calculation point etc.

Reflections - The following alternatives may be used:

None: Only direct noise in the calculation point
1: 1st order reflection is added, i.e. reflected noise reaching the calculation point via one vertical surface
2: 2nd order reflection is added, i.e. reflected noise reaching the calculation point via two vertical surfaces
3: 3rd order reflection is added, i.e. reflected noise reaching the calculation point via three vertical surfaces

Calculation using reflection takes more time than without. Especially using multiple order reflection the time increases exponentially with the order of reflections.

Show contribution from noise sources - If this option is activated, the noise contributions to the calculation point from each noise source are drawn in the map, see figure. Each contribution gets color according to the color scale from the box to the right of this button.

Color scale - By clicking the box to the right of Show contribution from noise sources, the dialog box Colour scale for calculation points appears (see vnnp_noisecolorscalestyle). The setting there will only affect the drawing of contribution from noise sources, not how the calculation points are shown.
Draw profiles - This generates drawings of each profile between the noise source and the calculation point for all roads/railroads and calculation points. If the calculation involves a large number of calculation points, it is recommended not to choose this option. The profiles may be deleted by choosing:

MOUS_ICO Menu: Noise > Deletion > Delete temporary data

The profiles show terrain profiles with barriers and buildings if any. If a barrier is included, reflection planes are drawn in front of and behind the barrier.

Lower, left corner

Sets the coordinates for the lower, left corner of the first profile to be drawn, if Draw profiles is on.

Choose < - Closes the dialog box and lets the user select a starting point in the map.
X - The X-coordinate of the lower-left corner.
Y - The Y-coordinate of the lower-left corner.

Others

OK - The dialog box is closed without performing a calculation, but saving the settings.
Cancel - The dialog box is closed without performing a calculation and without saving changes made in settings.
Help - Help text for this dialog box appears.

Calculation of alternative - Example

The following gives an example of the possibilities Novapoint Noise offers for defining alternatives. In this example, we are going to calculate noise levels for a new road (Designed in the Road model). Seven different alternatives for ten calculation points are to be calculated.

Alternative 0: calculation without measures.
Alternative 1: calculation with a low barrier.
Alternative 2: calculation with a reduced speed limit.
Alternative 3: calculation with a low barrier and reduced speed limit combined.
Alternative 4: calculation with a medium height barrier.
Alternative 5: calculation with a garage between the road and the calculation points.
Alternative 6: calculation with a different road alternative.

Common preparation (applies to all alternatives):

The terrain model is prepared, and the map is read. It is important that the group with the road to be used in alternative 0 (road 1) is active. The group with the road to be used in alternative 6 (road 2) must be passive.

Select the dialog box vnnp_noiseroads and add Road 1 to Novapoint Noise. In this box, also add traffic data for Road 1. Road 1 must be set active.

Select the dialog box vnnp_noisebuildings and add buildings that may affect the noise levels in any of the calculation points. These buildings must be active. Further, add the garage as a building. This building is to be set as passive (active in Alternative 5 only).

Select the dialog box vnnp_noisecalculationpoints and add all ten calculation points. They must all be set active.

Select the dialog box vnnp_noisehardgroundregions and add any areas which are to apply for all alternatives. These hard ground regions must be set active.

Select the dialog box vnnp_noisebarriers and add the barriers to be used in Alternatives 1, 3, and 4 respectively. These must all be set to passive.

Alternative 0

Select Calculation… and define alternative 0. This alternative may, e.g., be given the identity “Alt 0: No measures”.

Activate the option Reuse of profiles. This causes new terrain profiles to be saved for later use and already saved profiles to be reused (for the first calculation, no terrain profiles have been saved in advance).

To allow for access to detailed results, activate the option Save details.

Start the calculation.

Alternative 1

Select the dialog box vnnp_noisebarriers og and set the lowest barrier active.

Select the dialog box Calculation of alternative and define Alternative 1. The name of this alternative may e.g. be “Alt 1: low barrier”.

Activate the option Reuse of profiles. This causes new terrain profiles to be saved for later use, and already save profiles to be reused.

To allow for access to detailed results, activate the option Save details.

Start the calculation.

Alternative 2

Select the dialog box vnnp_noiseroadtrafficdata and change the speed limit.

Select the dialog box vnnp_noisebarriers and set the low barrier passive.

Select the dialog box Calculation of alternative and define Alternative 2. The name of this alternative may e.g. be “Alt 2: reduced speed”.

Activate the option Reuse of profiles. This causes new terrain profiles to be saved for later use, and already saved profiles to be reused.

To allow for access to detailed results, activate the option Save details.

Start the calculation.

Alternative 3

Select the dialog box vnnp_noisebarriers and set the lowest barrier active again.

Select the dialog box Calculation of alternative and define Alternative 3. The name of this alternative may e.g. be “Alt 3: low barrier and reduced speed”.

Activate the option Reuse of profiles. This causes new terrain profiles to be saved for later use, and already saved profiles to be reused.

To allow for access to detailed results, activate the option Save details.

Start the calculation.

Alternative 4

Select the dialog box vnnp_noisebarriers and set the medium height barrier active and the low barrier passive.

Select the dialog box vnnp_noiseroadtrafficdata and increase the speed limit again.

Select the dialog box Calculation of alternative and define Alternative 4. The name of this alternative may e.g. be “Alt 4: medium height barrier”.

Activate the option Reuse of profiles. This causes new terrain profiles to be saved for later use, and already saved profiles to be reused.

To allow for access to detailed results, activate the option Save details.

Start the calculation.

Alternative 5

Select the dialog box vnnp_noisebuildings and set the garage active.

Select the dialog box vnnp_noisebarriers and set all barriers passive.

Select the dialog box Calculation of alternative and define Alternative 5. The name of this alternative may e.g. be “Alt 5: garage as barrier”.

Activate the option Reuse of profiles. This causes new terrain profiles to be saved for later use, and already saved profiles to be reused.

To allow for access to detailed results, activate the option Save details.

Start the calculation.

Alternative 6

Select the dialog box vnnp_noisebuildings and set the garage passive.

Select the dialog box vnnp_noiseroads and delete Road 1.

NB! Delete all non-Novapoint Noise objects in the drawing.

Start the terrain model and set the group with road 1 passive and the group with Road 2 active.

The map is re-read to AutoCAD.

Select the dialog box vnnp_noiseroads and define Road 2 in Novapoint Noise. Also, add traffic data for Road 2. Road 2 must be set to active.

Select the dialog box Calculation of alternative and define Alternative 6. The name of this alternative may, e.g., be “Alt 6: other alternative”.

Upon entering the terrain model, all saved terrain profiles were deleted. If the new terrain profiles should be saved for later use, the option Reuse of profiles.

To allow for access to detailed results, activate the option Save details.

Start the calculation.

Presentation

Reports may be printed for all alternatives, including summaries and all details.

Alternatives 1-6 may be compared by printing text at calculation points for all alternatives simultaneously.

No warning will be given if for instance Alternative 3 had been calculated with the input data for alternative 2. The user is always responsible for checking that the input data are correct.

If in doubt about which input data was used for a specific alternative, look at the input data report. This report is ordered in the dialog box “Report” (see Report).

Next topic: Noise Contour Lines