Supporting Information
Source: data.gov.uk (2025-11-21)

GM Accessibility Levels (GMAL). Greater Manchester Accessibility Levels (GMAL) are a detailed and accurate measure of the accessibility of a point to both the conventional public transport network (i.e. bus, Metrolink and rail) and Greater Manchester’s Local Link (flexible transport service), taking into account walk access time and service availability. The method is essentially a way of measuring the density of the public transport provision at any location within the Greater Manchester region.

Please acknowledge the source of this information using the following attribution statement:

Contains Transport for Greater Manchester data. Contains OS data © Crown copyright and database right 2020. Contains Royal Mail data © Royal Mail copyright and Database right 2020. Contains National Statistics data © Crown copyright and database right 2020.

Greater Manchester Accessibility Levels (GMAL) Data – Supporting Information 
1 
About this document 
1.1 
This information note was last updated in January 2024.  It accompanies 
Transport for Greater Manchester’s GMAL data released at: 
https://data.gov.uk/dataset/gm-accessibility-levels 
1.2 
See the following sections for information on: 
 What is GMAL? 
 Copyright and licence details; 
 File formats; 
 Data specification; 
 Known issues and limitations; and 
 Data updates. 
1.3 
Please email xxx@xxx.xx if you have any enquiries or feedback 
about the data or this documentation. 
 
 

 
 
2 
What is GMAL? 
2.1 
The Greater Manchester Accessibility Levels (GMAL) dataset represents 
the accessibility from locations to the public transport network, taking 
into account walk access time and service availability. 
2.2 
There are two data files – one containing GMAL values for the centroids 
of a 100 metre square grid system covering Greater Manchester (the 
‘grid’ version), and one with values for the centroid of each postcode in 
Greater Manchester (the ‘postcode’ version). 
GMAL ‘grid’ version 
GMAL ‘postcode’ version 
Contains Transport for Greater Manchester data.  
Contains OS data © Crown copyright and database 
right 2016. 
Contains Transport for Greater Manchester data. 
Contains OS data © Crown copyright and database 
right 2030. Contains Royal Mail data © Royal Mail 
copyright and Database right 2020. Contains 
National Statistics data © Crown copyright and 
database right 2020. 
2.3 
Further information on how GMAL is calculated can be found in the 
accompanying “GMAL Calculation Guide.pdf” document. 
 
 

 
 
3 
Copyright and licence details 
3.1 
This free dataset is released under the Open Government Licence (OGL), 
a copy of which can be found here: 
http://www.nationalarchives.gov.uk/doc/open-government-
licence/version/3/  
3.2 
If you use the ‘grid’ version of GMAL, then please acknowledge the 
source of this information using the following attribution statement:  
Contains Transport for Greater Manchester data.   
3.3 
If you use the ‘postcode’ version of GMAL, then please acknowledge the 
source of this information using the following attribution statement: 
Contains Transport for Greater Manchester data. Contains OS data © 
Crown copyright and database right 2020.  Contains Royal Mail data © 
Royal Mail copyright and Database right 2020.  Contains National 
Statistics data © Crown copyright and database right 2020. 
4 
File formats 
4.1 
The dataset is available in a choice of file formats: 
 .tab (MapInfo) 
http://en.wikipedia.org/wiki/MapInfo_TAB_format 
 .shp (ESRI ArcGIS) 
http://en.wikipedia.org/wiki/Shapefile 
 .csv – only available for the ‘postcode’ version 
https://en.wikipedia.org/wiki/Comma-separated_values 
NB: The download files have been zipped to reduce file sizes. 
4.2 
The CSV file can be viewed in a wide range of software, but the TAB and 
SHP files require GIS software (e.g. MapInfo or QGIS). 
4.3 
Email us if you would like to request data in a format not listed here. 

 
 
5 
Data specification 
5.1 
Field names and types vary according to the file format. 
5.2 
The ‘grid’ version and ‘postcode’ version have the following data fields: 
Field name 
Type 
Grid 
version?
Postcode 
version? 
Meaning 
GridID  
Integer 
Y 
 
ID 
Postcode 
Char (7) 
 
Y 
Postcode 
Eastings 
Integer 
 
Y 
OSGB 
coordinates 
Northings 
Integer 
 
Y 
BusScore 
Float 
Y 
Y 
Constituent 
GMAL score 
for this 
mode 
RailScore 
Float 
Y 
Y 
MetroScore 
Float 
Y 
Y 
LocalLinkScore 
Float 
Y 
Y 
LocalLink 
Char (3) 
Y 
Y 
Is there a 
Local Link 
GMALScore 
Float 
Y 
Y 
Overall 
score 
GMALLevel 
Smallint 
Y 
Y 
Overall level
PTALTheme 
Char (2) 
 
Y 
PTAL 
Altrincham 
Char (4) 
Y 
Y 
Best journey 
time to this 
destination, 
in minutes 
Ashton 
Char (4) 
Y 
Y 
Bolton 
Char (4) 
Y 
Y 
Bury 
Char (4) 
Y 
Y 
ManchesterAirport 
Char (4) 
Y 
Y 
ManchesterMarketStreet 
Char (4) 
Y 
Y 
ManchesterOxfordRoad 
Char (4) 
Y 
Y 
ManchesterSpinningfields 
Char (4) 
Y 
Y 
Oldham  
Char (4) 
Y 
Y 
Rochdale  
Char (4) 
Y 
Y 
Stockport 
Char (4) 
Y 
Y 
TraffordCentre 
Char (4) 
Y 
Y 
Wigan 
Char (4) 
Y 
Y 
 

 
 
6 
Known issues and limitations 
6.1 
Some parts of the dataset may be less up-to-date than the rest, for 
example rail data.  See the Data updates section below for more 
information. 
6.2 
The PTALTheme field is not available in the ‘grid’ version. 
6.3 
Some past editions of the dataset included those school bus services 
which are available for the general public to use.  The GMAL calculation 
included these from February 2022 to July 2023 inclusive (NB: school 
services do not run during the holidays, i.e. August 2022, and April 2023).  
Consequently, there is a slight difference if comparing historic data from 
before and after these changes. 
6.4 
Transport for Greater Manchester would be interested to hear of any 
other issues that you come across. 
7 
Data updates 
7.1 
At the time of writing, Transport for Greater Manchester aims to update 
this dataset at least quarterly, if not monthly. 
7.2 
GMAL is calculated using data about the public transport network that 
existed on specific date(s).  These date(s) may differ from one transport 
mode to another, and can be found in the “Version.txt” file 
accompanying the data.