Boldyn Networks

Connecting London

Boldyn Networks


Installation Technology has been a trusted technology partner to Transport for London (TfL) delivering mission-critical solutions within its highly regulated and challenging rail environments for over 25 years.

In June 2021 BAI Communications UK (BAI) was awarded a 20-year concession by TfL to deliver their Telecommunications Commercialisation Project, a £2.2bn programme to improve connectivity across London. The concession included:

• The implementation of cellular coverage within the subterranean areas of the London Underground

• Construction of a commercial fibre optic network utilising TfL assets

• Utilisation of TfL's streetscape assets (e.g. lighting columns) for the deployment of radio coverage

• Provision of a public Wi-Fi service in specified TfL stations,

Installation Technology had recently completed the delivery of cellular connectivity within the eastern section of the Jubilee line and were continuing the enabling works for the Emergency Services Network* (ESN). Installation Technology’s intimate knowledge of delivering wireless connectivity within the TfL environment made Installation Technology the perfect partner for Boldyn to:

• Complete the delivery of ESN and

• Deliver a Commercial Mobile Service (CMS) to 137 stations and 400 kms of tunnel pairs

Given the sheer scale of the project and the extremely tight timescales, this was going to be Installation Technology’s biggest challenge to date.


Installation Technology had been working directly with TfL to undertake enabling works for the project for the past 4 years. Upon contract signature, Installation Technology, BAI and TfL worked closely together to create a co-ordinated transition from TfL’s enabling works team to BAI’s solution delivery team. 

Underpinned by a robust transition plan, clearly communicated to stakeholders with risks appropriately mitigated, the plan was executed within 6 months whilst maintaining the project’s momentum.

Having worked together for 4 years, Installation Technology and BAI had established a way of working as one team, encouraging challenges to be shared and solved collectively to avoid issues further down the line. 

Building on our ‘one team ethos’ we moved our Project Management Office (PMO), consultants and engineers to the BAI offices in Paddington and tripled the size of the enabling programme within 6 months of contract award. 

Implementing equipment within the London Underground environment is challenging. It is one of the oldest underground railways in the world, space for new equipment is tight, conditions are cramped , large temperature ranges occur and brake dust gets everywhere. 

All of these constraints were factored into the design to ensure the final solution is for purpose and serviceable for decades to come.

Working from TfL’s drawings, augmented with LiDAR (Light Detection and Ranging) scans of the tunnel sections undertaken by Installation Technology in 2019, desktop designs for the on-site equipment locations were completed.

Site surveys followed and will continue until project completion, with adjustments made where re-positioning is required. Designs are then sent to TfL for approval. Applications for the space equipment will occupy is the final step before implementation can commence.

Trackside installations must be completed when services are not running as train services cannot be stopped. With weekend services, this means that on many lines work can only be carried out in the middle of the night, an engineering window of just 4 hours.

To meet the project’s challenging timescales within these short delivery windows, we are now coordinating a workforce of over 500 technicians and engineers every night including weekends, to keep pace with the implementation schedule.

The London Underground is a tightly regulated environment that requires;

• Suitably trained and accredited operatives to carry out work

• Risk Assessment Method Statement (RAMS) to be submitted and approved before work can commence

• A Site Person in Charge (SPC) accredited engineer to manage the works site and be present at all times

• The appropriate approvals are in place to allow the work to be undertaken in-line with TFL standards

All of the above are applied with Installation Technology’s 25 years of experience in how these processes, standards and accreditations are applied within the operational railway environment.

Following on from our TfL Beacon Safety Award in Feb 2019, in October 2022, we surpassed 5 million hours of service without incident.


The high-level design to provide the coverage requirements for the CMS and ESN was a neutral host Digital Distributed Antenna System (DDAS). One of the benefits of this solution is the active equipment is clustered into 9 large Base Station Hotels (BHS) spread throughout London. 

Grouping the equipment into 9 sites reduces the cost of delivery and ongoing support whilst satisfying the Home Office’s resiliency requirements for ESN.

The neutral host model also facilitates the sharing of much of the active and passive infrastructure, reducing the amount of equipment and BSHs required, leading to significant reductions in cost.

All four UK mobile operators, Three, EE, Vodafone and Virgin Media O2 have signed up to be part of the wider programme following the success of the pilot in the eastern section of the Jubilee line. With established relationships and working practises firmly in place with TfL, BAI and the mobile operators. the programme is progressing well through the various project milestones.

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Once the cellular network is complete, mobile users will have continuous high-speed 4G and 5G connectivity across the Tube, including tunnels, with seamless handover to the mobile networks aboveground. 

As currently enjoyed on the eastern section of the Jubilee line, customers will be able to check the latest travel information, keep on top of their emails, check the latest news, catch up on social media, watch videos or make a call throughout their journey. 

When the new Emergency Services Network (ESN) becomes live, first responders will receive immediate access to life-saving data, images and information in live situations and emergencies on the frontline.

Billy D’Arcy CEO BAI Communications UK said, ‘Installation Technology are our largest supply chain partner with whom we’ve built a trusted relationship over the last 5 years. Our teams work as one, collaborating and innovating in the delivery of this exciting programme for London, one of the largest projects of its kind in world’. 

* Transport for London is a local government body responsible for the transport system in Greater London. TfL has responsibility for London's network of principal road routes, and rail networks including the London Underground, London Overground, Docklands Light Railway and TfL Rail.  

** ESN is the replacement for TETRA, a secure UK wide cellular network used by government agencies and Emergency Services within the UK.


Low power radios


Kms of structured cabling


Kms of leaky feed


Low power radios


Kms of structured cabling


Kms of leaky feed