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.

For the development project to proceed, it was necessary to build adjacent to and over the top of these tunnels. In conjunction with Network Rail, the asset owner, it was agreed this could take place, provided any movement of the tunnels and track was analysed and a real-time monitoring scheme installed. The monitoring scheme was required to confirm predicted movements, and measure any exceedances, so work could be stopped before any damage to the infrastructure occurred, minimising risks to travellers and trains.

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

Robust- 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

佩尔·弗里奇曼（Pell Frischmann）, one of the UK’s leading consulting engineering companies with almost 100 years of experience, accepted this monitoring challenge. Having used various Leica Geosystems’ instruments and equipment for over 30 years, the company knew thatLeica 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.”

There were two independent monitoring systems installed at King’s Cross Station – the primary one was geodetic monitoring with automatic total stations (ATS) and the backup one was geotechnical monitoring, providing redundancy in measurements, delivering additional information and increasing certainty and reliability of results.

伦敦隧道的量身定制解决方案

The equipment used for the project consisted of following sensors:

Leica TM30/50监视总站提供了缩小测量激光束检测亚博5分钟快三器灵敏度的能力，从而消除了这些长线性位点中相邻目标的干扰风险，这是Leica Geosystems仪器的独特能力。这使系统能够使用较少的总站配置，同时仍保持网络导轨所需的目标频率。亚博5分钟快三监视仪器自动衡量：

• 隧道三维位移测量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!。

由于项目的复杂环境和长线性性质，两端仅具有稳定的区域，因此总站数据需要对均匀模型的校正，而不是独立工作的每个单元。因此，在观察周期期间，使用Star*Net Software由Microsurvey Software Inc.进行了实时计算对照网络的完全集成和自动化的最小二平方调节，这是Hexagon的一部分。亚搏苹果app然后，在每个监视阵列观察之前，将对整个网络的实时网络调整坐标自动更新Geomos系统。

“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

有几个复杂的魅力llenges 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。

“The equipment delivered accurate and repeatable results 24/7 for extended periods of time without the need for manual intervention between the standard bi-monthly maintenance visits. This was particularly important in the Gasworks tunnels, where diesel residue and water leakage caused a particularly harsh working environment, in which the instrumentation had to operate faultlessly for 12 months between servicing,” said Weekes.

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

Once the 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.

“客户和所有利益相关者对系统及其性能都很满意。他们特别喜欢实时对数据的无限访问，这使他们能够检查任何次要的触发器，并看到趋势，而无需在系统上进行任何专业知识或培训。我们计划在公司的合作网络中分享对该产品的满意度，因此可以在各种项目中使用。”

“佩尔·弗里奇曼（Pell Frischmann）提供了与Leica Geosystems和更广泛的Hexagon团队紧密合作的创新解决方案。亚搏苹果app他们已经迅速回应了任何问题，包括过时的时间，并将项目从火车的任何延误的费用中挽救了。