In a series of blog posts earlier this year, BAI Communications looked at the roll-out of wireless communications in metro rail environments like New York, Toronto and Hong Kong. Here are the top five challenges BAI faced when deploying communications networks underground and the lessons learnt:

1 – Dealing with dust

Underground railways are hostile environments to work in. Heat, humidity, and poor air quality are just some of the conditions that must be considered in the planning stages of any underground project.

When it comes to the issue of poor air quality, a major contributor is the brake dust released by friction between brake pads, wheels and rails. Steel based, it’s pervasive, conductive, and a significant threat to the smooth running of sensitive telecoms electronics.

Addressing the issue requires the use of enclosures designed to keep dust out, avoiding equipment failure, and even the risk of fire. Given the safety implications, and the unique characteristics of each underground environment, it may be necessary to create a new design from scratch. While this can take time, sourcing a solution that is discreet, vandal and graffiti resistant, and most important of all, future-proof and reliable is worthwhile.

2 – Completing complex projects without disrupting passengers

Many cities operate metro rail services that stop for just a few hours a night, with some even running 24/7. Popular with passengers, this provision of almost constant service presents authorities with a challenge – how to conduct essential maintenance, or integrate new technologies, without disrupting timetables.

Getting this right relies on flexibility and preparation. Work must be scheduled during breaks in service, typically at weekends or overnight. In addition, it’s not unusual for work due to take place in one location to be postponed at the last minute. As a result, contingency plans are required so teams can be quickly reallocated to other sites.

The ability to innovate is also incredibly important. During work on Hong Kong’s metro communications network, the size of tunnels presented challenges that had the potential to push back completion. Safety requirements prohibited the use of conventional ladders, requiring scaffolding instead – considerably more time-consuming to set up and move. To avoid delay, a new platform ladder was sourced that was lightweight, easy to transport, and, most importantly, saved at least 30 percent of the time needed to use traditional scaffolding.

3 – Mind the gap – Delivering comms in confined spaces

Delivering high-speed wireless connectivity requires suitable places to install sensitive electrical equipment. Finding them is more difficult in underground tunnels where ceilings are often low and space is at a premium. Any location needs three key features: interference-free communications coverage, protection for equipment against damage and the ability to restrict unauthorised access.

Ultimately, finding the perfect placements requires highly detailed planning, including surveying equipment locations in every station and tunnel to ensure compliance with requirements. Technology can play a huge part in this process – in Hong Kong laser-based measurement was used across every site to guarantee that trains would not strike the newly installed equipment.

Meanwhile, in New York’s subway, 3D visualisation, like that used by Google in its Street View application, was used to speed up the entire planning process. Station planners could see how the installation would work once in use, and where the best locations for equipment were, all whilst ensuring the right aesthetics were maintained. While this approach provided a highly accurate way of demonstrating compliance, it also saved the time, hassle and expense of frequent site visits.

4 – Developing subterranean skillsets

Finding employees with the right skills is central to success in many industries and is particularly relevant when it comes to underground connectivity given the numerous regulations governing which installation engineers can work on site. Further, while these contractors are highly professional and very experienced in electrical and mechanical installations, they often need to acquire new skills when it comes to telecom infrastructure deployment.

These skills are critical as the coax cable and fibre used for high-speed wireless services require careful handling and precision fitting to avoid performance degradation. Even the smallest errors, like a kink in the cable, can seriously impact user experience. As a result, finding contractors that fulfil the criteria required for underground rail and possess the skillset required for installing next generation mobile communications networks can be challenging.

The team responsible for the roll-out of Wi-Fi and mobile coverage across the New York subway faced this issue when the deadline for completion was brought forward, shaving two years off the original schedule. Meeting the new deadline required a doubling of the contractor workforce, the majority of whom had limited experience working with fibre.

To meet the completion deadline without compromising quality, installation teams were structured to have a highly experienced lead who directed contractor engineers with less experience in telecom cable installation. By taking a creative approach to team structure, it was possible to complete the job within the challenging new timeframe and to the high standard required.

5 – Aligning transport and telecom business models

Rail, both inter-city and metro, is characterised by the huge investments it makes in its infrastructure. Rail systems remain in service for decades and trains are typically purchased on a 30-year cycle. In contrast, the telecom industry is fast-paced, driven by the ever-accelerating rate of technology development and short system lifecycles.

In terms of structure, rail authorities tend to be monolithic, taking on most of the responsibility for infrastructure and operations. The telecom industry, on the other hand, tends to be built on partnerships, involving numerous stakeholders with different specialisms.

Marrying these philosophies requires a change in approach. Taking the time to develop relationships between key personnel at the transport authority and the telco provider is essential to streamline processes. Doing so can help to ensure quick and easy access to trackside areas so that partners can work with the flexibility and efficiency required for next generation telecom deployment.

This was also central to the success of the New York subway installation. Taking the time to forge true partnerships between competing companies in the early stages ensured effective coordination when the completion date was brought forward. Being able to pull all parties together to agree a solution was a key part of the process.

The importance of experience and innovation

Each underground system is a unique environment. Any communications solution must be tailored to address different challenges, from tight turns and low ceilings to heat exposure and dust pollution.

As these five examples have shown, BAI has always had to plan extensively and innovate in the face of unexpected challenges. Taking this kind of engineering approach to solving technical problems ensures high quality services, reliability and long-term future use.