urrently underway in one of London’s wealthiest areas, 
the De Vere Gardens development is located on the site 
of two recently demolished hotels in Kensington and 

Chelsea, next to Hyde Park. The project will provide two new 
seven-story buildings and one five-story block incorporating 
retained façades. In the middle of the site, encompassed on 
three sides by extensive building work (including the enlarge-
ment of the existing basement to two levels), is a block of 15 
privately owned flats. Sir Robert McAlpine, Ltd., a leading UK 
building and civil engineering company, is the main contractor 
on the De Vere project. In this pricey and historical area, moni-
toring the buildings and the retained facades for structural 
damage is a critical part of the contract. 

Having realized inadequate results from a monitoring subcon-
tractor, McAlpine decided to perform the monitoring itself. 
The monitoring system had several requirements: It had to be 
managed in-house; it had to be automated, real-time, reliable 
and easy to use; and above all, it had to be in place before piling 
began—a tight timeframe. 

“The tight time schedule was significant for us,” explains Senior 
Land Surveyor Vince Bridle, the manager tasked with installing 
and overseeing the system. “Understandably, residents were 
concerned about structural damage to their property. We felt 
that a comprehensive monitoring program would help alleviate 
their fears.” The team looked at several systems, ultimately 

selecting a real-time solution of two Trimble S8 robotic total 
stations with Trimble 4D Control software. 

“We were already familiar with the hardware and software, which 
cut down the learning curve,” says Bridle. “And having seen the 
system demonstrated on a small-scale project, we knew that we 
could manipulate it for our specific requirements. Strong vendor 
support to get us up and running was also a factor.” 

Moving Targets
A control network of 13 base targets was established on 
site, and 98 25mm prisms were fixed on the structures to be 
monitored. The total stations were positioned at opposite 
ends of the site, one on the McAlpine site building and the 
other on the highest point of a retained façade wall, where 
there was sufficient room to power it with three solar panels. 
A 2.4-GHz wireless radio link connects the total stations to 
an office PC running the Trimble 4D Control software, where 
email and text alerts are generated automatically.

Trimble 4D Control software post-processes the monitoring 
data collected by the total stations. It computes rounds of 
angles measured in the field as individual sessions and reveals 
any movement of targets over time. The terrestrial engine in 
Trimble 4D Control processes each session, validates the data, 
then stores the point information together with the raw data. 
Other modules of the software use this data to create warnings 
and alarms, as well as graphs and reports.

Monitoring London’s Upper Crust