What are Vertical Streets?

What is a Vertical Street?

• “Vertical Streets: A list of polygons for locations that contain more than one postcode, for example, office blocks and flats.” – Code-Point with Polygons – Overview​

• Vertical Streets are a representation in the Code-Point with Polygons product of things like office blocks or flats where a single building contains more than one postcode​

• For more information on Code-Point with Polygons please refer to the Code=-Point with Polygons section of the OS website​

Why do they exist?

Vertical Streets can exist for 2 main reasons:​

• There are too many residential addresses in a building for one postcode so multiple postcodes are required (there are 121 addresses in Green Court shown below)​

• There are multiple businesses in a building, some of which will have unique postcodes, meaning there are multiple postcodes in a building​

AddressBase Core shown over OS MasterMap Imagery Layer showing two tower blocks in Luton, one called Green Court

How do you know if a postcode is in a Vertical Street?

The information relating to Vertical Streets is only held in Code-Point with Polygons.

When Code-Point with Polygons is viewed in a GIS all of the Vertical Streets appear as small square polygons (shown in orange here), when they are clicked on they have a ‘postcode’ attribute beginning with V

This a Vertical Street reference and is in three parts.

• V – denoting a Vertical Street reference

• A 1 or 2 letter postcode region in this case of the image below it would be E

• A 5-digit number starting at 00001 in each postcode region and rising sequentially, in this case of one of the postcodes below 00796

• This makes a reference of VE00796

Vertical Street postcode polygons highlighted in orange, Code-Point points in blue

In Code-Point (show here in blue) the postcodes that form the Vertical Street are all within the building they relate to, sometimes stacked, sometimes spread out, but they do not have a reference back to the Vertical Street polygon they are part of

How do you join the Vertical Street data?

In the data supply for Code-Point with Polygons in the ‘Data’ folder will be a folder called ‘VERTICAL_STREETS’.

This contains a TXT files for each postcode area listing all of the postcodes that are part of Vertical Streets and their associated Vertical Street reference.

In the image below these would be the codes VLU00217 to VLU00224. These show that the Vertical Streets are within the Luton LU postcode area and are numbers 217 through to 224.

These can either be joined to the Code-Point with polygons data in a database or in a GIS, or can be left as a separate look-up table

If joined to the polygons data, then when a user clicks on the Vertical Street polygon in a GIS then the associated postcodes can be identified

A combination image showing the list of lookup TXT files, a sample of the content and the associated area on a map

What if you ignore them?

As of the July 2022 release of Code-Point with Polygons there are 150,513 Vertical Streets containing 231,864 postcodes. This is ~10% of the postcodes in Code-Point.

These postcodes contain a total of: 3,044,020 residential addresses and 918,401 commercial addresses. This is ~10% of addresses in AddressBase

Ignoring these will then skew any analysis that uses postcode data

Distribution of vertical streets

What can you do with them?

A lot of recording of ‘events’ is done against postcode. For example, Covid test ordered by postcode. If Vertical Streets are ignored, then this will create gaps in the data and the recording of ‘events’ against postcode when it comes to visualising that data geographically.

The presence of a large number of vertical streets quickly indicates a high density of either businesses or residential properties.

From a resilience perspective, it quickly allows an emergency planner to identify buildings that have a high number of residential addresses or a number of businesses that might need to be evacuated in an emergency.

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This content has been developed from what was originally a Lightning Talk PowerPoint slide set. These slides are available to PSGA members to view and download from the PSGA members area of the OS website