Recent Posts

71

Support / I can't select tiles, and the status bar shows the tile as ------. What's wrong?

« Last post by roger on December 12, 2014, 11:56:45 AM »

Your model is in the middle east and your typical model co-ordinates are (800 000, 2 600 000). In other words, your model is 800 km east of the origin and 2,600 km north of the origin.  NoiseMap will only allow you to have 7FF by 7FF (Expressed in Hexadecimal) tiles in a model, ie 2048 by 2048 tiles, expressed in decimal. Since the tiles are 500 m square by default, your furthest point can only be 1024 by 1024 km from the origin.

Your scheme, whilst large, only covers about 50 km by 50 km, so can easily be accommodated in NoiseMap.
All you need to do when creating the scheme is to set the origin to, say, (700 000, 2 500 000) and your problem will go away. Note that you cannot have negative co-ordinates (you cannot go west or south of the origin) so don't put the origin in the middle of your scheme, but well to the south and west of the scheme.

PS If you do need a larger model, you could set the tile size to something larger, say 1000 m in the 'remote server' version only. This can have other downsides, so only do it if you must.

72

Support / How do I export the 24 by 1-hour noise levels?

« Last post by roger on December 12, 2014, 10:45:21 AM »

I'm doing a project outside the UK where they are using a different averaging period. I have put in 24x1-hour traffic flows for every road (a major task).  How do I get out the 24x1-hour Leq levels?

Firstly, as you have appreciated, it is a lot of work to put the traffic flows in, but this is overshadowed by the number of results, particularly if you have a lot of combinations to export.  To avoid having a vast output file - 24 results for each combination, for each receiver, for each floor level, we have chosen only to output either the standard indexes (which will be wanted by most UK users), or the 'Headline Result' for each receiver, floor level and combination.

When you select the headline result calculated from hourly traffic data, you can choose the averaging time  for the L10 and Leq parameters.

So if you want the average level for the morning peak, say starting at 7 am and ending at 10 pm, download the results for all receivers and then select Calculate>Receiver Result Display Parameters, select Leq as the Result Type and in time period, select 07:00 to 10:00
Then go to Calculate>Export Receiver Results
Uncheck Export All Result types that can be generated from loaded result data.
This will ensure that only the headline result will be exported and will prevent the export of the various L10, Lden, Ld, Le, Ln results which will be extensive if you have a lot of combinations to export.

NoiseMap will then export the Leq average over the specified time period. Note that if you don't adjust the time period, by default the Leq output is the 16-hour average from 07:00 to 23:00 and the L10 output is the 18-hour average from 06:00 to 00:00.

On a final point, when exporting receiver results, if you want all the loaded receiver results to be output, ensure that no receivers are selected (or that all of them are selected). If just some receivers are selected, only the selected results will be exported.

73

Hints and Tips / My script file will only calculate the first scenario and ignores the rest

« Last post by roger on December 01, 2014, 07:08:13 PM »

As you will appreciate, NoiseMap can only load one scenario at a time. If you try to load a new scenario from the on-screen menu, you will be asked if you want to clear the existing one first. But in the script system, NoiseMap just refuses to load the new scenario, so it won't be calculated.

To avoid this, after the calc command, you need to put

clear model

before the next load command.

74

Hints and Tips / Importing traffic flows from spreadsheet, can NoiseMap put in the flow IDs?

« Last post by roger on December 01, 2014, 06:52:45 PM »

Yes, the rules for importing traffic flows from a spreadsheet are:

• If the flow ID number matches a flow ID already in the database, the flow values in the spreadsheet replace the flow values in the database;
• If the flow ID number does not match a flow ID already in the database, the flow value in the spreadsheet is added to the database;
• If the flow ID number in the spreadsheet is zero, then NoiseMap creates a new flow ID and adds the value in the spreadsheet to the database.

Option 3 avoids you inadvertently replacing a value already in the database. NoiseMap does report the number of flows added and changed - it is a good idea to check this to ensure that the update option has worked as you expected.

75

Support / SiteNoise Calculation Options

« Last post by roger on November 19, 2014, 10:44:37 AM »

There are a huge number of options with SiteNoise Calculations. Can you give any advice on how to choose the right ones?

The options in SiteNoise tend to reflect its development since 1989. SiteNoise has always tried to remain backwards-compatible, so that people using old models can still get 'historic' answers.

This is why there are options to use or ignore the angle of view correction for haul roads, and slant distance for distance calculations. These weren't in the early version of the BS, but should be used now for correctness. Similarly, the simple 0/5/10 barrier correction was in the early BS because without a calculator and a 3-d model, it was difficult to use a path-difference method.

Unfortunately, the new BS barrier calculation method needs not only the path difference, but also the source spectrum, which is often not available even now.  If you don't have the source spectrum, you will have to fall back on the 0/5/10 or CRTN methods, noting that CRTN can give a lot more than 10 dB of screening and is fine if you are dealing with engine-driven plant.

However, if you have a spectrum, you can use the BS5228:2009 barrier correction calculation, which is likely to give you a bit more attenuation for engine-type sources than the CRTN method. This may be partly due to the fact that CRTN was devised for dealing with the attenuation of L10 from line sources.

The soft ground correction is slightly more tricky.  BS5228-1:2009 requires a correction for the average height of propagation and source-receiver distance. The CRTN method also requires this, but give higher values of correction (lower noise levels).  At 600 m, for an average height of propagation of 2 m, BS5228 give a soft ground correction of about 6 dB, as does CONCAWE (which does not take average height of propagation into account), but CRTN gives 9 dB.  It may be noted that where there is screening, this will often be more than 9 dB, so this predominates and the value of soft ground correction is not relevant.

Atmospheric absorption is not explicitly included in the BS or CRTN methods (although it may be implicit in the distance attenuation calculation).  It isn't usually significant for engine-type sources at closer distances, but it is required for wind farm calculations.  It is applied to the spectrum if you have one, or to the A-weighted value (using the values for 250 Hz) if you don't.

Note that CRTN and BS5228 were set up to calculate for typical downwind propagation conditions, so there is no additional correction for wind direction.

People commonly use the CRTN method for barrier and soft ground if they don't have a spectrum and they use the BS 5228:1997 (equivalent to BS5228:2009 method) if they do have a spectrum. It may be confusing to mix part BS and part CRTN as it is possible there could be some co-dependency between the various adjustments.

The User Manual has more detail on the calculation method but ultimately, the user must rely on their own expertise.

76

Support / I work on my own: would the remote server version benefit me?

« Last post by roger on October 07, 2014, 04:55:12 PM »

Firstly, we should mention that there isn't a separate 'remote server' version as such - the normal version will connect either to the standalone database or the 'server' database (as long as your licence permits this). Also, the server doesn't have to be 'remote' - it could be in your own PC.  However you do have to instal the server and NoiseMap can provide the licence and download for this.

There are still advantages to the server edition even if you are working alone, and even if it is in your own PC.  The main benefit is that you can submit calculation runs to the 'Calculation Queue' which is held on the server. If you have a complex project with many scenarios, this means that you can keep on editing on your own PC without having to wait for the calculation run to finish. When you have finished, you connect your PC to the queue and let it run overnight to produce all your results.

Even better, you can connect another PC  to the calculation queue to do the calculations whilst you are getting on with the editing of new scenarios.  You'd need a licence for that PC, but NoiseMap supplies inexpensive 'calculation only' licences for that purpose.

If you don't want the hassle of setting up your own server, NoiseMap runs a remote server on which you can hire database space.  With today's fast broadband connections, this can give you the advantage of the server edition without having to set up a server.  It can be a big time-saver on larger projects.

77

Support / What is the range of validity for road traffic data?

« Last post by roger on October 07, 2014, 10:58:53 AM »

CRTN states that its formula are valid over a 'quoted range of validity', although the range is implied by the charts rather than explicitly stated.  It's easy to forget this range of validity when using computer software.  NoiseMap attempts to trap out-of-range values and to issue warnings.  For traffic flow data, the range of validity implied by the charts is:
Flow Rate - 50 to 10000 vehicles per hour and 1000 to 200000 vehicles per 18 hours.
Mean speed - 20 to 130 km/h
Percentage of heavies - 0 to 80 %

However, if you use TRL Method 2 (i.e. using day, evening and night traffic flows to calculate Lden values), you MUST have non-zero values for flow rate, speed and percentage heavies for the three time periods and the 18-hour value, otherwise the method cannot be used.

The explanation is as follows:
The method has a term in the conversion formula that takes 10 times the log of ratio of the product of the period flow data values in the numerator  and the 18-hour flow values in the denominator. So if the percentage of heavies is zero in the 18-hour case (and thus zero in the period case), the conversion term is zero divided by zero and the value can't be calculated.  The term would be uncertain if any of the periods have zero values, as it would become the log of zero which is also undefined.  [A more normal expectation is that the flow will be, say, 20 % of the 18-hour flow, with the speed and percentage heavies not greatly different from the 18-hour values.  This would give a value of -7 dB.]
Thus method 2 cannot be used if the percentage of heavies, flow rate  or speed are zero in any period. You might be able tp fix this by putting in a small value, say percentage heavies = 0.1, which causes this term to tend to a value of zero, and it drops out of the equation.

For the other values, remember the limits on validity of speed and flow rate. If you put a speed of less than 20 km/h (or the gradient correction causes it to fall below this value) NoiseMap uses a value of 20 km/h. 

If the flow rate is less than 200 veh/h or 4000 veh/18 h, (common on residential roads and non-motorway roads at night) then CRTN makes a low-flow correction to L10, but the conversion formulae do not adjust the period Leq for this effect.  It is, however, implied in the night-time conversion formula for non-motorway roads, according to the TRL report.

78

Hints and Tips / How do I put building numbers onto a noise map?

« Last post by roger on October 04, 2014, 04:36:00 PM »

There are several ways that you could do this.
If you have an OS digital map, then if you search the various layers you will find that several layers contain text labels.  This should include house numbers and house names. 

Although the OS standardises the feature codes used in its maps, you may find that if they have been supplied by, say, a local authority, you will have to do a bit of searching to find out the feature codes that are most useful to you.  You may be able do this by opening the dbf part of the shapefile in Excel and looking through the columns to find the most useful one.  Make a note of the feature code that identifies the house numbers and also the column that contains the house numbers (or other labels that you want to use). You should ensure that the house numbers are defined as text rather than numeric values, as NoiseMap needs you to import these as a text descriptor. [If they are numeric values, you will need to use the Excel TEXT function to convert them to text values.  A slight issue is that although Excel will read in dbf files, it will no longer export in that format and you will need a third-party add-in to restore that function.]

Then import the shapefile, choosing the column containing the feature codes for 'use as layers'.  this will ensure that each different type of feature will be put into a separate layer.  This is essential so that you can use the 'convert layer' function.  Choose to import as a 'descriptor' the column containing the house numbers.  Thus, you will now have a layer that contains the house numbers.

Now go to Convert Layer and select the layer that contains the house numbers.  Choose to import this as an outline and choose outline type 'Annotation 1'. [This has the smallest font.]  The houses will now be numbered/named! Commit the changes. [Remember to do this in a base scenario so that the house numbers will be available in all child scenarios.]  If you can't see the house numbers, make sure that labelling for outlines and also for the 'Annotation 1' outline type is on in Display options.

If you don't have the OS house numbers, you might have an AddressPoint file.  This also has house numbers and you can convert these using a similar procedure.  One difference is that OS usually label house numbers selectively, whereas AddressPoint has every house numbered - often several numbers per house - so it is not as neat.

You can use a similar approach to labelling street names.

79

Hints and Tips / In the database previewer, what does 'include parent tiles' do?

« Last post by roger on October 01, 2014, 12:04:23 AM »

The Database Previewer is a multi-purpose interface to the noise model. Its main purpose is to let you download the model for a particular scenario and a particular area.  When you select the scenario of interest in the upper window of the previewer, NoiseMap highlights only the tiles where one or more geographical features are different from the features of its parent scenario.

However, if you want to see the complete model for the scenario, you also need to include the tiles from the parent scenario which were not altered in the child scenario, so you check the 'Include parent scenario' box.  This may cause a large number of additional tiles to be downloaded, but you can limit this by using the 'named area' feature.

Note that in the previewer, selecting a named area does not include the unaltered tiles from the parent unless you tick the 'include parent scenario' option.

Also, remember that only the tiles visible and highlighted in the display will be downloaded.  This also helps to prevent very large areas to be loaded by mistake.

However, when editing or printing out a model, be careful not to inadvertently exclude tiles: in these cases it is normally necessary to ensure that the 'include parent tiles' box has been ticked.

80

Support / What supplementary manuals do you have?

« Last post by roger on August 03, 2014, 07:00:06 PM »

The following written manuals are available in pdf format. Please email support@noisemap.com, stating your company name and registered licence (dongle) number (if you have one) to request a copy.
Remember also to search this forum for further hints and tips.

An Introduction to NoiseMap five (August 2012)
NoiseMap 5.1 User Manual (Feb 2014)
NoiseMap five Script Interface Guide (Feb 2011)
NoiseMap five - Assessing Road Schemes (Dec 2009)

How SiteNoise Works - Construction Schedules (May 2014)
How SiteNoise works - Mining (Sept 2013)

RailNoise from Simple Maps (Sept 2008)
RoadNoise from Simple Maps (Sept 2008)
Using DXF and Shape Files (Nov 2011)
Shapefile contents (October 2013)
Categories and Combinations (Quick Guide) (July 2007)
Distributed Calculations (Quick Guide) (April 2009)
Converting CadnaA models (June 2013)
DMRB Processing (Sept 2013)
How to prepare vertical contours (Jan 2013)

The benefits of a NoiseMap Maintenance contract