C D Surveys were commissioned to carry out a topographical survey in the Farringdon area of London, the job entailed approximately 200 meters of road with around half being pedestrianized. This may seem a straightforward task, yet as many surveyors will know this often not the outcome when working in London as the case quickly became apparent.
I arrived early around 7.15 and encountered my first problem…. Parking, surveying usually requires a lot of equipment and this job was no different. So I found the closest car park (only a ten minute walk to site location) and set off for a reconnaissance mission.
Initially all seemed straight forward then as I turned the corner onto the pedestrianized area of the site I saw it straddled 2 underground stations and some of the survey area was on Cross rail land. I spoke to my office and was assured that I had permission to survey both areas but would have to arrange with cross rail for an induction. The plan was to survey all the accessible areas of site on the first day then return to carry out the cross rail area the following day.
After spraying up the survey site at five metre cross sections (one of the specifications), I returned to my van to get my survey equipment on the way picking up a much needed coffee. As with many London survey jobs, the specification also included all road markings, street furniture and all services.
The actual survey work on the majority of the site went without too many problems, apart from the usual members of public/cars/vans/taxis/charity workers getting in the way. Also, as with all London jobs, I had to position the stations in a way that I could lock the instrument to something as they do have a tendency to “walk away” sometimes.
One of the requirements of the work was that I had to tie into some existing control stations, this made it slightly more laborious as the closest of them was approximately 600 meters away and had to be incorporated into the traverse loop. After a long day of work I got back to the van, paid the exorbitant parking charge and made my way home (slowly) to process my work and check for any errors that could be resolved the next day.
There is one problem with working close to cross rail sites
that for future reference is quite beneficial to know, there are many
monitoring prisms dotted around on buildings……. As I found out, to my annoyance when I came to
process my work later that night. When observing one of my forward stations
with a pole the robotic instrument had locked onto a 360 degree prism directly
behind me. Whilst not being catastrophic
as I could see that 99% of my work was good, I couldn’t close out my traverse
to check my accuracy due to the duff shot. This just meant a few more
observations for the next day and a bit more caution was needed in future.
Another early start, same parking place then down to the cross rail site for the induction, all carried out without a hitch in bright orange (as anyone who has worked on railway sites would know). As I was only going to be on the cross rail site for a few hours that day I was given a chaperone for the day who had to follow me everywhere…… well almost everywhere. Again the majority of the work went without a hitch bar the locking onto all the monitoring prisms in the local vicinity.
I had taken my laptop so that I could avoid any unnecessary returns to site and also enable me to process the work from day 2 and resolve the traversing problems from day 1. Once this was done I printed off some verification sheets and annotated any heights, surface changes whilst also checking for any missing services or detail.
All in all quite a detailed job with some unforeseen problems that thankfully were reasonably easily resolved, another day another survey.
30th August 2017
At the start of the year CD Surveys were approached to discuss how we can carry out a monitoring job to assess if the concrete foundations for two…Find out more