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Support / What tolerance should I use when converting railway tracks?
« Last post by roger on September 13, 2020, 12:33:27 PM »
Q. When I set the tolerance to zero, NoiseMap crashes (sometimes it just hangs forever).
A. Your input data has already divided the railway tracks into 10 m segments.  Experience shows that NoiseMap will keep to the original 10 m tracks if you set the tolerance to a low value, say 0.1m.  I suspect that if you set the tolerance to zero, then due to the precision with which decimal values can be stored in in binary values in the computer, there will be some values that can't be represented with zero tolerance. As a result, the curve-fitting algorithm will try forever to get an exact fit, which is unachievable.  Hence the program appears to hang. 
The answer is to set tolerances to a small value, say 0.1 m, and NoiseMap will stick to the original segmentation.
Support / Creating PDFs
« Last post by admin on August 04, 2020, 02:40:22 PM »
I've seen your advice to use a 'pdf printer' for making portable high-resolution maps.  I have tried a 'freebie' pdf printer but NoiseMap will only create maps at A4 size.  What should I do?

NoiseMap creates maps at an exact scale on any printer.  To do this it needs to know the exact size of the 'paper' on which it is printing, even if it is virtual paper.  Because any printer might be connected to the computer, Windows requires the printer driver to supply the hardware characteristics of the printer back to the user software (in this case NoiseMap).  Unfortunately some poorly-written printer drivers don't do this properly, and it is even more complex with 'virtual printers' where paper size and other characteristics are simulated in software. Whilst good PDF software will allow you to change things like paper size, if they don't supply this change back to NoiseMap, there is no way that NoiseMap knows what size of paper has been chosen and it will probably default back to A4 or US letter size.

The solution is to use one of the printer drivers that we recommend, such as Adobe Acrobat or Win2PDF, or to try out various others for yourself.  Do be careful with 'freebies'.  These may carry malware or 'Adware' which could turn out to be very expensive in the long run.
Announcements / NoiseMap 5.2.10 released 29 October 2018
« Last post by roger on April 03, 2019, 03:03:11 PM »
NoiseMap 5.2.10 was released in October 2018 and contains a number of major improvements.

ISO9613-2 Barrier Calculation
The headline feature in this release is a new ISO9613-2 barrier calculation option.  This option is part of the SiteNoise Calculation module, which is based on BS5228 with enhancements.

This adds to the existing barrier calculation options in the SiteNoise module, so now you can choose from:
• ISO9613-2 barrier calculation
• BS5228 simple barrier calculations,
• BS5228 octave band spectrum barrier calculations,
• CRTN barrier calculations.

The ISO calculation requires octave band noise source data, as the attenuation is evaluated for each octave. The ISO procedure has a ‘meteorological correction’ which has the effect of reducing the path difference used to calculate the barrier attenuation.  This correction is used to take into account the scattering of sound into the barrier’s shadow zone, caused by atmospheric turbulence under downwind propagation. This means that the barrier attenuation will be less than calculated by some other procedures.

Many new scripting options have been added – allowing you to import and export Categories and Combinations, and to export full analysis of calculation details for receiver points.

[The intermediate versions between 5.2.6 and 5.2.10 were not public releases.]
Hints and Tips / Modelling low traffic flows
« Last post by roger on April 03, 2019, 02:49:06 PM »
Calculation of Road Traffic Noise (CRTN) states that is unreliable in situations where flows are less than 50 vehicles per hour.  How should traffic flows on a waste disposal site be modelled when they are this low?

CRTN is based on the LA10 value, i.e. the noise level  exceeded for 10 % of the time. When flows are very low, vehicle noise may not be present at significant levels for 10 % of the time, in which case the LA10 is more a function of the ambient level than of the traffic noise.  This is probably the case at 50 veh/h which is less than one vehicle per minute. 

Here, you would be advised to use the ‘haul road’ calculation of BS5228, given in the ‘SiteNoise’ module of NoiseMap, which provides the LAeq of the source.  This calculates the contribution of sound energy from each moving point source, so is applicable to any flow rate and speed, as long as you have the sound power level or LAmax at 10 metres for the applicable vehicle speed. 

This will give an appropriate calculation of the LAeq values.  As previously noted, LA10 is probably not the most appropriate index to use in these situations. 
Support / Sloping or overhanging barriers in Rail Noise Calculations
« Last post by roger on December 03, 2018, 12:32:19 PM »
CRN and TNPM don’t provide for sloping or overhanging barriers.

NoiseMap did implement an overhanging capability for use in Hong Kong, where the overhanging barriers were also absorbent.

We are not aware of much in the way of research on this matter (other than measurements we took in Hong Kong), although admittedly we have not searched for recent work.  If users are aware of any guidance, then we will be glad to consider it.

For these reasons, the implementation in NoiseMap is very simple:  we assume that an overhanging barrier behaves as a simple barrier with the diffracting edge at the lip of the overhang.  We have assumed absorptive properties because we assume that there is no reverberant field within the enclosure space.  This is because the behaviour of sound within the space between the train and the semi-enclosure is not accurately defined. It will depend on many factors like separation distances.

Is the overhanging barrier tool is the best one to model the sloping barrier situation?
We think that if the diffracting edge is above the top of the train envelope, this would be the best way to do it. If the barrier slopes down toward the train, then reflections off the barrier will be directed downwards, so the assumption of absorbency would be reasonable.

If the sloping barrier is still at a distance from the nearside track, you could model it as a vertical barrier closer to the track and then you can choose whether or not to use absorbency.

This is an area that would benefit from further research.
Support / Exporting the detailed corrections in receiver calculations
« Last post by roger on November 23, 2018, 06:20:29 PM »
When doing receiver calculations, the 'Live' calculation will let you view the value of each correction that makes up the contribution of each source segment to the total noise level.  When you choose to store receiver calculation results in the database, the make-up of each calculation is not usually available, partly because the amount of data can be so large.

However, you can select this option using the contribcsv script file parameter in the calc receivers script command, as follows:
Command "calc receivers" details:
    Description: Perform or queue a set of stored receiver calculations
    Parameters: tiles - Tiles specified as a comma-separated list of NoiseMap tile references or tile reference ranges
                area - Tiles specificied as a NoiseMap named area
                method - Noise calculation method, eg. Lden,RoI(2005) or Leq,16h(03)
                surround - Tile surround for load and calculation
                recalc - Force recalc switch for calculation
                queue - Calculation - queue calculation switch
                coa - CRTN parameter: cut-off angle
                cor - CRTN parameter: reflection cut-off
                cod - CRTN parameter: cut-off distance
                maxeffbar - Maximum number of effective barriers to search during calculation
                engines - Number of calculation engines to use (or use "auto" or "integrated")
                contribcsv - Path to root folder within which to save noise source contribution csv files for each receiver

Note that the contribcsv parameter will let you specify a target folder within which the output you need is written. Note that you specify a folder not a file as NoiseMap will create a structure with a sub-folder for each tile, and then a separate file for each receiver. So you can queue up a bunch of calculations and point at a single shared root folder (on a network drive) and have multiple computers fill it up as they process tiles.

The detailed data is not stored within the database so you do have to re-run the calculation even if you’ve already done it (the database results will also be updated, although again not with all the additional data).

This option is for the specialist use of those who need to do further post-processing of the calculations.
You will need to provide your own post-processing software/spreadsheet for such work - it is not part of NoiseMap.

Support / Upgraded security on Pay-As-You-Go Address (URL)
« Last post by roger on October 22, 2018, 06:30:25 PM »
As part of a programme to improve security, the link to our Pay-As-You-Go pages now requires you to use https:// as follows:

This will take you to the login page which operates as previously.
Support / My licence says it has expired
« Last post by roger on October 15, 2018, 11:45:59 AM »
There are two parts to a NoiseMap licence - the main licence that allows you to use NoiseMap, and the maintenance section that allows you to receive support and updates.  When you have a permanent licence (actually a 50-year licence) we still set it to expire after five years, but we renew it free of charge when it expires.  This is just in case you lose the dongle or it is stolen.  We don't want someone else to have continuous use of NoiseMap. 

The second part is the maintenance.  This is a valuable service that gives you updates and technical support.,  It is particularly important when you first buy a licence.  Firstly because we don't want you to delay buying a licence in case there is an update 'just around the corner', and secondly new users may be the greatest beneficiaries from technical support. 

However, we have a policy of issuing worthwhile updates about once a year, and sometimes interim updates more frequently.  So if you would like to receive updates and support continuously, it is worth renewing your maintenance annually.  Maintenance generally costs about 20 % of the as-new price, so this means that you get continuous updates and support for the same price as buying a new licence every five years. 

You will get a reminder of the expiry of your main licence from about one month prior to expiry.  This is generated from within the software, so you won't get a reminder if you don't run NoiseMap.  However, the licence status is always given on the Output Screen when you start NoiseMap, so if you don't use it continually, it might be an idea to make a note in your calendar.

If you are on an annual licence, it is a similar situation. 

NoiseMap five licences can be renewed by issuing you with an activation code.  Just email us and we will deal with it.
NoiseMap Enterprise licences can also be renewed remotely, although this needs us to send you a 'Dongle Recovery File'.  Again, please email us and we will be glad to help.

You will get a similar reminder about maintenance, although if it does expire, NoiseMap will continue to run: you just won't get any further updates or email support.

We don't usually issue emails about new releases of NoiseMap.  However, you can always check by starting NoiseMap and going to Help>Check licence status if you are running NoiseMap five.

If you are running NoiseMap Enterprise, then log into our website and check the News section for announcements.

In fact, the website has a great deal of information on updates to NoiseMap five as well.  Sometimes, the significance of updates may not be obvious and it is well worth looking at the News announcements in particular as these might highlight something that is important to you.  Recently, these have included enhancements to the scripting functions: not something that everyone uses, but if you are engaged in some of the huge projects currently being undertaken, you could find these very helpful.
Hints and Tips / What sort of digital mapping do you recommend?
« Last post by roger on June 14, 2018, 11:08:19 PM »
Digital mapping has greatly improved over the last few years.  In the UK, the Ordnance Survey 1:1250 maps, known as MasterMap, are the most detailed maps, showing all mapping objects, with each object separately identified.
These are now provided in a variety of formats and we recommend Shapefile format as being the easiest to use with NoiseMap.  Building height and topographical data is also available.  OS have an agreement to provide local authorities with digital mapping and if you are working for a local authority, they may be able to provide you with Shapefiles of the area, provided to sign a licence agreement. Otherwise, OS prefer it if you buy the mapping from one of their 'partner' companies, who generally charge according to the size of the area and the terms of the licence.

We have written some detailed guidance on the use of digital mapping with NoiseMap, which is available to download from our website, on this link:
Hints and Tips / What is the best way of segmenting roads?
« Last post by roger on May 23, 2018, 04:28:06 PM »
'Calculation of Road Traffic Noise', CRTN, states in para 11:  that roads should be divided into ‘a small number of segments’ such that ‘within any one segment the variation is less than 2 dB(A)’.

NoiseMap has an automated segmentation feature which generates segments along the road alignment to fit the horizontal and vertical curvature of the road to within a selected tolerance.  We recommend that this should be 1 m horizontally and 0.5 m vertically.

This is a geometric fit, rather than an acoustical fit.  However, it should be sufficient to deal with any variations in sound level due to distance and gradient.

Screening is more difficult because this is dependent on the position of the receiver relative to the position of screening objects. NoiseMap deals with this by sub-dividing the primary segments according to the position of the screening objects: indeed, the sub-divided primary segments are then further sub-divided by secondary screening objects. This sub-division is a complex process that takes up most of the calculation time, but ensures that multiple barriers are correctly assessed even if the primary segments are very long.

It should be noted that CRTN advises that roads are divided into a small number of segments.  This is an important proviso: in particular, if you follow the 'TRL' conversion procedure from L10 to Leq,t, this can be affected by the noise level emitted by each segment: very short segments will emit very little energy individually and this can distort the conversion formula.

Accordingly, we would not advise on pre-segmenting into say 10-metre segments as this could contravene the first part of the CRTN advice about ‘a small number of segments’ and then cause issues with converting the results to Leq,t.  This is particularly the case when using conversion methods 1 and 2.
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