Black boxes
Request ID: FOI-0519-1920
Date published: 19 June 2019
You asked
F/on from IRV-133-1819
Thank you for the reply.
The design drawing does appear to show the location of the small black box. Given it’s size, I cannot see how this can be described as a ‘Post Joint Large’. I wonder whether this refers to the larger pieces of infrastructure which are located nearby?
I have recently seen some images which I attach here for your information. Image 007, shows the infrastructure in July 2014. As can be clearly seen, the small box is located close to the larger box and could not be considered a foreseeable trip hazard to pedestrians. There is also the ‘medium’ sized box further up the street. Skip forward to 2016 (image 008) and the big black box is moved next to the medium black box , but the little black box that caused the accident stays in place. It is no longer in close proximity to the large black box. I wonder if the little black box was only supposed to be on a pavement if it was adjacent to a larger black box. The taller black box is more visible.
And more recently, someone put a cone over the little black box (image 009)! It would appear that this was temporary risk reduction after my wife’s injury.
Returning to your reply, you state, “The location of the PJL would be covered as part of item number 8 of the Traffic Signal Safety and Quality Check.” I have tied to find this item 8 in the documentation already supplied to me and it does not seem to be there.
You go on to say, “...which is then passed to another team within the organisation who are accountable for instructing the works by the signal installation contractors. Unfortunately I have been unable to locate any further information to address the remainder of your request.” Whilst I share your frustration, this information must exist!
I therefore ask the following questions;
1. What are TfL’s design policies and guidelines for the siting of these various sized black boxes?
2. Are the small black boxes supposed to be left ‘orphaned’ when other work is undertaken?
3. Are the small black boxes routinely installed in isolation on pavements?
4. What is the relationship between the ‘large’, ‘medium’, and ‘small’ black boxes in terms of their functions? A reply in normal English rather than a technical explanation would be most beneficial.
5. As you now have an indication of the dates that work was carried out on this set of boxes, can you please disclose the works orders and documents relating to it?
6. I was told that the small black box was being relocated as a matter of urgency. Can you confirm that this work has now been undertaken?
7. Can you confirm that the cone was merely a temporary measure to reduced the risk of pedestrian injury? Please disclose any policy documents relating to the use of the cone.
We answered
TfL Ref: 0519-1920
Thank you for your request received by us on 21 May 2019 asking for information about the installation of a small black box, a street based item of signal infrastructure also known as a Post Joint Large (PJL).
Your request has been considered in accordance with the requirements of the Freedom of Information Act and our information access policy. I can confirm that we hold the information you require. You asked:
1. What are TfL’s design policies and guidelines for the siting of these various sized black boxes?
Transport for London’s (TfL) guidance for signal design is provided in the ‘SQA-0643 Design for Signalised Junction’ which states that:
The boxes should be located at the back of the footway where possible, adjacent to a wall or fence, where the likelihood of damage from vehicular collision is reduced. They should be positioned to avoid creating a trip hazard, obstructing private property, doorways, accesses, shop windows or footways.
All boxes should be oriented so that the door is easily accessible for a maintenance engineer and allow unimpeded use of the footway by pedestrians, those using wheelchairs or pushing prams.
2. Are the small black boxes supposed to be left ‘orphaned’ when other work is undertaken?
3. Are the small black boxes routinely installed in isolation on pavements?
The Guidance provided in our response to Question One should be followed.
4. What is the relationship between the ‘large’, ‘medium’, and ‘small’ black boxes in terms of their functions? A reply in normal English rather than a technical explanation would be most beneficial.
Large – Traffic Signal Controller: Includes all programed information required to operate the traffic signals. All signals are connected back to this.
Medium – Electrical Supply Pillar: Distributes incoming electricity supply to the traffic signal controller to power the signals
Small – Post Joint Large (PJL): Provides a communication line to the Traffic Signal Controller from TfL’s central computer to manage signal co-ordination and provide fault monitoring.
5. As you now have an indication of the dates that work was carried out on this set of boxes, can you please disclose the works orders and documents relating to it?
A task/word order instruction was issued to our contractor to complete the works.
6. I was told that the small black box was being relocated as a matter of urgency. Can you confirm that this work has now been undertaken?
I can advise that this has now been resolved and we have installed a larger feeder pillar.
7. Can you confirm that the cone was merely a temporary measure to reduced the risk of pedestrian injury? Please disclose any policy documents relating to the use of the cone.
We can confirm that the cone was installed as a temporary measure prior to the new box being installed.
If this is not the information you are looking for, or if you are unable to access it for any reason, please do not hesitate to contact me.
Please see the attached information sheet for details of your right to appeal as well as information on copyright and what to do if you would like to re-use any of the information we have disclosed.
Yours sincerely
Jasmine Howard
FOI Case Officer
Information Governance
Transport For London
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