Underneath King’s Cross redevelopment

Authors: Lidija Špiranec & Steven Thurgood

King’s Cross is one of the most significant reconstruction projects in London, UK. The area around King’s Cross Station had 67 acres of unused land, which was designated for development in 2008. The master plan included 50 buildings, 1,900 new homes, 20 new streets, 26 new public parks and squares and 26 acres of open space.

Renewal work for this major rail hub began in 2010. One of the key constraints of the project was the presence of four railway tunnels beneath the site, which were part of the main connections with King’s Cross Station. These connections are utilised by hundreds of thousands of commuters every day.

为了进行开发项目，有必要在这些隧道的顶部建造邻近和越过。资产所有者的Network Rail结合使用，只要对隧道和轨道的任何移动进行分析，并安装了实时监控方案，就可以同意这可能发生。需要监视计划以确认预测的运动并衡量任何超越的运动，因此可以在发生任何损害基础设施之前停止工作，从而最大程度地减少对旅行者和火车的风险。

Due to the size of the project, its value and impact, the monitoring system requirements were rigorous:

强大的- to last the contract duration of 12 years
Scalable- to accommodate expansion
准确 /精确- to measure and report with confidence
Repeatable- to obtain consistent observation
Automated- to run in an environment with no manned access
Continuous- to operate 24/7
Accessible- to all stakeholders

Pell Frischmann这是英国领先的咨询工程公司之一，拥有将近100年的经验，接受了这一监视挑战。该公司在使用了各种Leica Geosystems的工具和设备已有30多年的历史Leica Geosystems的监视解决方案were the right way to go, on account of reliability, technical excellence, backup and support. Thus, the firm partnered withSCCS Survey Equipment Ltd, part of Hexagon，英国Leica Geosystems测量设备的领先分销商，以提供所需的监视系统。

“Leica Geosystems’ long history of developing new products, whilst fully maintaining backwards compatibility, ensured the system could be expanded with the latest equipment over the extended duration of the project. At the same time Leica Geosystems’ maintenance and support network meant that spare parts and servicing would be available for all purchased equipment, whatever its age, over the entire project life-cycle,” said Gary Weekes, director asset management at Pell Frischmann. “The support of SCCS in helping to specify suitable equipment and assist with setting up the system was also a key driver in selecting Leica Geosystems equipment for the project.”

国王十字架上安装了两个独立的监控系统 - 主要的是，一个大地监测，具有自动总站（ATS），备用一个是岩土技术监测，可提供测量的冗余，提供更多信息，并提高结果的确定性和可靠性。亚博5分钟快三

伦敦隧道的量身定制解决方案

The equipment used for the project consisted of following sensors:

The Leica TM30/50 monitoring total stations provided the ability to narrow the measuring laser beam detector sensitivity, eliminating the risk of interference from adjacent targets in these long linear sites, which is a unique ability of Leica Geosystems’ instrumentation. This enabled the system to be configured with fewer total stations while still maintaining the target frequency required by Network Rail. The monitoring instrumentation automatically measures:

• 3 d隧道displacement by measuring five prism arrays attached to the tunnel lining at 10m cross sections

• 通过测量轨道上每个导轨的棱镜对，用于恒定，扭曲，量规和对齐的导轨几何形状

在隧道之外，测量了一个稳定控制点的永久网络，以消除总站的运动。亚博5分钟快三

The wireless tilt nodes were installed on the tunnel lining adjacent to the crown prism and track bed/sleepers at 3m intervals to mirror rail prisms. The wireless tilt and distance nodes were located on the tunnel lining at each 10-m cross section to measure convergence and ovalisation of the tunnel.

Once everything was installed, a track geometry measuring device with scanner and its dedicated software was used to measure/verify the tunnels and ensure the monitoring equipment was clear of passing trains and kinematic envelope.

使用Leica Geosystems促进了所有测量和岩土测量的数据获取和处理GeoMoS Monitor。允许分配优先级和控制观察值的软件，而观察频率则可以调节以匹配动态事件。棱镜测量的计算结果进一步用于计算数学得出值的虚拟观察点，从而使各种数据源的复杂计算成为单个计算模型。定制变量根据活动和仪器定义了变形运动限制，警报和动作。数据可视化和报告使用Leica GeoSystems的基于云的服务无缝集成GeoMoS Now!。

由于复杂环境和长时间的线性nature of the project with only stable areas at each end, the total station data required correction to a homogeneous model rather than each unit working independently. Thus, a fully-integrated and automated least square adjustment of the control network was computed real time during the observation cycles using Star*Net software by MicroSurvey Software Inc., part of Hexagon. The GeoMoS system was then automatically updated with live network adjustment coordinates for the entire network prior to each monitoring array observation.

“The use of GeoMoS Now! enabled us to establish simple, clear dashboards for the project. At any time, there were multiple contractors onsite, who were only interested in individual sections of the monitoring scheme. GeoMoS Monitor allowed specific alert regimes to be established for each contractor, with individual dashboards developed in GeoMoS Now!, which were login specific to that contractor.“, explained Weekes.

Overcoming monitoring challenges

There were several complex challenges that the Pell Frischmann team had to overcome during the monitoring period. In the Thameslink Tunnels, trains were passing at 50 mph every five minutes, causing vibration and air movement, affecting instrument orientation and level. The access to the tunnels was limited to two four-hour shifts every three months, so a permanent solution was found by installing GeoLaser AD-12 self-levelling tribrach to enable remote users to correct the total station back to the horizontal plane without requiring access. This was fully controlled via GeoMoS Monitor.

In the Gasworks Tunnels there was a different challenge to be overcome – an oily soot residue. The brickwork in the tunnels had thick layers of it built up over time from the years of steam and diesel trains operating in the tunnels. This caused constant residue built up throughout the monitoring period. Therefore, the total station optics and prisms needed to be cleaned every couple of months to maintain signal strength, as part of the active maintenance plan.

在安装寿命上，在SCCS的持续支持下，监视计划运营商发现了创新的解决方案，以提高系统可靠性并降低运营成本。这还包括抗腐败配件和棱镜覆盖物，使它们能够抵抗隧道中发现的以前未知的环境条件的持续暴露。

“设备在长时间的长时间内提供了准确且可重复的结果，而无需在标准双月维护访问之间进行手动干预。这在Gasworks隧道中尤其重要，在那里柴油残留物和漏水导致了一个特别严厉的工作环境，在这里，在维修之间，仪器必须在12个月内无障碍地操作。”

The reliability and accuracy of the equipment ensured that all work on the development near the tunnels could continue without any delays a decade later from 2010. This instilled confidence in the system from Network Rail and there has been no need to stop or slow trains, avoiding any financial penalties delays would have incurred.”

Future-proof monitoring data

一旦regeneration of King’s Cross is completed, monitoring of the tunnels will continue. The importance of this dataset rests in recording the natural movement and condition of the tunnel. This could become an important asset for engineers to determine life cycle extensions of the tunnels and to plan preventative maintenance.

“The client and all stakeholders were very happy with the system and its performance. They particularly liked the real time unlimited access to the data, which enabled them to check any minor triggers and see trending without the need for any specialist knowledge or training on the system. We plan on sharing our level of satisfaction with this product within this collaborative network of companies, so it can be utilised on a wide range of projects,” concluded Weekes.

“Pell Frischmann provides innovative solutions working closely with Leica Geosystems and wider Hexagon team. They have responded promptly to any issues, including out of hours and have saved the project from the costs of any delays to trains”, added Alastair Mitchell, project director of Kings Cross Partnership.