What is the purpose for surveying the line using theodolites?

[Darren R]

Earlier this afternoon I watched from the kitchen window as a team of suitably high-viz wearing gentlemen and their lookouts walked along the trackside (in the cess), stopping at regular intervals to use the theodolite and measuring stick. Judging by the train horns I could hear for some time after they had passed, they continued along the line doing the same thing for quite a distance.

This is the second time I have witnessed this, the last time being around a month ago. Just what, exactly, would they have been surveying? Not being a surveyor, (nor a railway employee - just a nosy neighbour!) I don't know the ins and outs of theodolite use, but I thought they could only be used for measuring either distances or gradients. Surely the latter are well documented and fixed - landslides excluded - and there are more efficient ways of measuring the former?

I've been observing the daily comings and goings on the line from my kitchen window now for (ahem) several years and can't ever recall seeing this happen before. I've also noticed a big increase in various test and measurement train activity over the past year or so - in fact I think I've seen more activity of this kind during the last twelve months than I did through 25 years of BR ownership! Could the two be related, or is it just coincidence?

Of course in my mind it's because they are measuring-up for electrifcation - but I think I'm being over-optimistic on that one!

 

[The Ham]

Earlier this afternoon I watched from the kitchen window as a team of suitably high-viz wearing gentlemen and their lookouts walked along the trackside (in the cess), stopping at regular intervals to use the theodolite and measuring stick. Judging by the train horns I could hear for some time after they had passed, they continued along the line doing the same thing for quite a distance.

This is the second time I have witnessed this, the last time being around a month ago. Just what, exactly, would they have been surveying? Not being a surveyor, (nor a railway employee - just a nosy neighbour!) I don't know the ins and outs of theodolite use, but I thought they could only be used for measuring either distances or gradients. Surely the latter are well documented and fixed - landslides excluded - and there are more efficient ways of measuring the former?

I've been observing the daily comings and goings on the line from my kitchen window now for (ahem) several years and can't ever recall seeing this happen before. I've also noticed a big increase in various test and measurement train activity over the past year or so - in fact I think I've seen more activity of this kind during the last twelve months than I did through 25 years of BR ownership! Could the two be related, or is it just coincidence?

Of course in my mind it's because they are measuring-up for electrifcation - but I think I'm being over-optimistic on that one!

Theodolites can be used to create a full 3D topograpical survey, hoever from your discription they didn't appear to be stopping for very long in each location. As such it may well be that they were undertaking a lazer survey which creates millions of points of evey surface they hit and is very useful in creating a 3D model of the area being surveyed.

 

[WSW]

Earlier this afternoon I watched from the kitchen window as a team of suitably high-viz wearing gentlemen and their lookouts walked along the trackside (in the cess), stopping at regular intervals to use the theodolite and measuring stick. Judging by the train horns I could hear for some time after they had passed, they continued along the line doing the same thing for quite a distance.

This is the second time I have witnessed this, the last time being around a month ago. Just what, exactly, would they have been surveying? Not being a surveyor, (nor a railway employee - just a nosy neighbour!) I don't know the ins and outs of theodolite use, but I thought they could only be used for measuring either distances or gradients. Surely the latter are well documented and fixed - landslides excluded - and there are more efficient ways of measuring the former?

I've been observing the daily comings and goings on the line from my kitchen window now for (ahem) several years and can't ever recall seeing this happen before. I've also noticed a big increase in various test and measurement train activity over the past year or so - in fact I think I've seen more activity of this kind during the last twelve months than I did through 25 years of BR ownership! Could the two be related, or is it just coincidence?

Of course in my mind it's because they are measuring-up for electrifcation - but I think I'm being over-optimistic on that one!

Are you sure it was a theodolite? In the traditional sense, a theodolite measures angles, in the horizontal and in the vertical, and is used to fix position. These days, a theodolite is often combined with an electronic measuring device - a "total station". The mode of working is often a traverse - between two known reference stations. It might have been a level, especially if used with a levelling staff (a kind of large ruler ) and the usual mode of working is similar - a linear progression between known reference points. Levelling (usually) determines differences in heights. Or they might have been using a very high precision GPS (sub cm).

As for why they are doing the survey work near you, well, that could be for almost anything!

Steve
(retired surveyor)

 

[edwin_m]

I believe surveying generally indicates a major renewal or enhancement when accurate data on the position of track and other assets is needed. Between times monitoring is mainly by specially equipped trains which check the geometry of the track and overhead line and the clearances to nearby structures.

If you're prepared to post your location, we could speculate on what planned projects might affect it. There is quite a lot of electrification in the pipeline for parts of Lancashire!

 

[Joseph_Locke]

IIf you're prepared to post your location, we could speculate on what planned projects might affect it. There is quite a lot of electrification in the pipeline for parts of Lancashire!

Not Just electrification!

 

[broadgage]

As others post it is probably in preperation for electrification work or other upgrades, such as ascertaining what work is required to clear the route for larger loading gauge trains.

Less likely but still possible answers include determining clearances UNDER railway assets for new or upgraded below ground structures such as sewers, culverts, pipes, or tunnels. Or to check clearances ABOVE railway assets for electric power cables or telecomms equipment.

 

[Ploughman]

Did you say what line they were surveying?
If it was any line other than the WCML or other Electrified line then there may be some tamping or possible renewal of the track coming up in the next 12 months or so.
Not all survey work is carried out by Total stations methods a lot is carried out using tried and tested older methods especially on areas of, shall we call it Rustic Railways.

If the team were doing a Level survey then this may be to produce a Vertical Profile drawing to illustrate the track gradients and from that to work out a better profile.
If the team were later to be seen doing something similar but maybe with a Theodolite then they may be producing a Horizontal drawing especially if the track is generally straight. This again to improve the alignment.
Both methods look initially similar with a gang of Lookouts, a Surveyor and someone on a staff.
With the Vertical level survey the staff man will be using the staff vertically on the rail top while with the Horizontal survey he will be holding the staff against the side of the railhead. The surveyor will either be using a Level or a Theo respectively.

Some Renewals offices do this to maintain a skill level within their staff rather than contracting out the design work to design companies especially on simpler sites that do not involve OHLE, Drainage or structures.

 

[asylumxl]

The use of a "measuring stick" makes me think they were probably using a level, be it a laser level or an optical one. Ofcourse it could have been a total station but I can't say i've heard of anyone refer to a prism staff as a measuring stick...

This is a levelling staff...

With the addition of a detector for a laser level...

Where as a prism looks like this..

If you can tell us which one you saw, we can tell you what they were most likely doing .

 

[work-traveller]

You say the same activity took place about a month ago. Possibly there's a track monitoring exercise under way. I've seen this done when there concern about potential subsidence or effects from adjacent activities, i.e. groundworks on a construction site.

 

[Trog]

Could it be an old fashioned theodolite straight being done?

Where a thodolte is used to set out a line between pegs in the cess more or less parallel with the track. Then a six foot folding ruler and a nice bright orange pencil are used to measure the offsets from the nearest rail to the line of the theodolite. Back in the office the offsets can be plotted on graph paper, and slues worked out to give a design alignment. All a bit BR stone age for the modern world but your local maintainers may still have someone who knows how to do it.

 

[Ploughman]

Could it be an old fashioned theodolite straight being done?

Where a thodolte is used to set out a line between pegs in the cess more or less parallel with the track. Then a six foot folding ruler and a nice bright orange pencil are used to measure the offsets from the nearest rail to the line of the theodolite. Back in the office the offsets can be plotted on graph paper, and slues worked out to give a design alignment. All a bit BR stone age for the modern world but your local maintainers may still have someone who knows how to do it.

Rather than use the folding ruler we just used the staff held horizontally.
Booked the results as you would for a level section.

 

[Trog]

Rather than use the folding ruler we just used the staff held horizontally.
Booked the results as you would for a level section.

We indicated left and right to the man with the pencil, and he did the booking, you can see an orange pencil with a nice fresh black rail pad behind it for a very long way with a good theodolite. You can also use the same kit to check the theodolite has not moved after each train as well.

 

[Ploughman]

By using the staff and if the cess is clear you can site the Theo well off track, say 4 metres, beyond the effect of any passing train and if near a junction or signal you can still survey while a train is sat waiting.

 

[Darren R]

Thanks for the info guys, interesting stuff. I called it a theodolite because that's what it looked like to the untrained eye. Unfortunately I couldn't get a really good look at their closest point because of the folliage! They were definitely walking down the cess though, not the pw itself - they did exactly the same last time too. I didn't see any evidence of any attachments to the measuring post they were using, nor the 'theodolite' head itself, but I couldn't say for sure. If they come past again I'll go and have a proper shufty!

The line in question is that between Bolton and Blackburn. Mostly single track with passing loops, no freight at all (except departmentals), no longer a diversionary route, and heavily engineered throughout with several high/lengthy viaducts and a very damp tunnel over a mile long beneath a moorland bog - I would say electrification is never going to happen. But then again a couple of years ago I'd have said the same about the Todmorden Curve reopening! And of course the wires will be going up soon(ish) at the Bolton end too as part of the North West electrification scheme. I also read (much to my amusement at the time) the possibility of wiring the line was mentioned as something to be examined more closely for carrying forward as a proposal in the latest RUS.

I was intrigued because they were surveying along the line - if it was just a small area or structure that would have made more sense to me. But as I said in the thread opener, there has been an awful lot of surveying/measurement activity over the past year or so. The Laser survey train has been past, the NMT twice and several measurement trains both the converted 150 and the loco hauled. I've also just come across this on RTT for this Friday:
http://www.realtimetrains.co.uk/train/U72617/2013/06/07/advanced

Looks to be something like a measurement train of some sort, but it traverses the line four times! I'm greatly interested as to what that turns out to be (if it runs!)

 

[Joseph_Locke]

The line in question is that between Bolton and Blackburn.

Its for the extension of Darwen Loop, not a Northern Hub or Electrification job.

I shall have words, that survey should be finished by now.

 

[Darren R]

Its for the extension of Darwen Loop, not a Northern Hub or Electrification job.

I shall have words, that survey should be finished by now.

Say what now - extending the Darwen loop????? How did I miss that one being announced! (Or has it not been yet?)

Are you able to give any further details on a public forum?

Since I can see the signal protecting the entrance to the loop from one of the upstairs windows, I know the line fairly well! I don't see how the current loop can be extended towards Bolton very far: One bridge would have to be rebuilt to double track and because of the commencement of a long reverse curve all the way to the northern portal of Sough Tunnel signal positioning would be a major problem. Extending the loop towards Blackburn would be much easier, but I don't see what is to be gained operationally from doing so.

Any further information you are able to give would be greatly appreciated - and if it's still not in the public domain I promise I won't tell anyone!

 

[Joseph_Locke]

Are you able to give any further details on a public forum?

I can confirm that some of the stuff mentioned in http://www.theboltonnews.co.uk/comment/comment/yourview/9955329.Full_steam_ahead_for_improved_rail_links/ is true, particularly after this led to a visit by the Hon. Mr Straw to the local headquarters of a certain national railway infrastructure company, just for a chat you understand.

Initial study suggests that your narrative is probably right - just Blackburn side of Sough to just Darwen side of the M65 bridge.

The key point is that a longer loop gives more opportunity for two services to pass each other, allowing those services' times to be adjusted to better fit into the surrounding routes' traffic patterns, e.g. Manchester-Bolton, Preston-Blackburn, etc.

 

[pablo]

So this project is not so much a loop extension as a subtle piece of double track re-instatement?

 

[eMeS]

The use of a "measuring stick" makes me think they were probably using a level, be it a laser level or an optical one. Of course it could have been a total station but I can't say I've heard of anyone refer to a prism staff as a measuring stick...
...
If you can tell us which one you saw, we can tell you what they were most likely doing .

How do modern Total Stations with all their internal electronics like working in the vicinity of the 25KV OHLE? Are they used, or does their use require the power to be turned off? Just wondering... I own several (old) non-electronic theodolites which I assume would not be affected.

 

[asylumxl]

How do modern Total Stations with all their internal electronics like working in the vicinity of the 25KV OHLE? Are they used, or does their use require the power to be turned off? Just wondering... I own several (old) non-electronic theodolites which I assume would not be affected.

As far as I'm aware they shouldn't have any issues, although I don't survey railways so I may be mistaken.

I've certainly seen them used many times during the running of trains, so I'm assuming the OHLE wasn't turned off.

 

[edwin_m]

As the OLE doesn't affect any of the electronic devices carried by passengers, it's highly unlikely to affect surveying instruments.

 

[eMeS]

As the OLE doesn't affect any of the electronic devices carried by passengers, it's highly unlikely to affect surveying instruments.

Good point, but it affected my recordings when filming on the platform at Wolverton Station. There was a lesser effect when I was outside the platform area in the adjacent car park.

 

[Trog]

As the OLE doesn't affect any of the electronic devices carried by passengers, it's highly unlikely to affect surveying instruments.

The OHL emits more interference in some places than others, and the weather also has an effect. I have known the detecting rodeyes used for surveying with a laser go crazy when the metal staff they were attached to touched a rail. The whole survey was eventually carried out with a rubber rail pad between the rodeye and the rail.

(Yes BR was happy for us to use aluminium staffs that would extend to 5m under live OHL. How did we use them, very carefully.)

Non electronic survey equipment could also have problems, as getting an electric shock to your eyeball every time you looked through the level was somewhat disconcerting. In the worst places all the metal fittings on the survey equipment had a buzz to them, and felt a bit like touching the sticky side of cellotape.

 

[Joseph_Locke]

I'd remind Mr Trog about steel Hallade wire, but I'm sure he hasn't forgotten the regular belt you got from 30m of piano wire. Every 15m. For miles.

Zap. Ow.




Zap. Ow.




Zap. Ow.




Zap. Ow.

 

[Ploughman]

Or from seeing a welders straight edge weld itself to the rail when it was in use for lining up a weld. 3 miles from the nearest OHLE.

 

[PaxVobiscum]

As the OLE doesn't affect any of the electronic devices carried by passengers, it's highly unlikely to affect surveying instruments.

Ah, but the pax are in a Faraday cage.

 

[edwin_m]

Not when they are on a platform.

 

[Trog]

I'd remind Mr Trog about steel Hallade wire, but I'm sure he hasn't forgotten the regular belt you got from 30m of piano wire. Every 15m. For miles.

Zap. Ow.




Zap. Ow.




Zap. Ow.




Zap. Ow.

Must admit I never had that problem, but that may have something to do with me using mono-filament fishing line instead of piano wire.
--- old post above --- --- new post below ---

Or from seeing a welders straight edge weld itself to the rail when it was in use for lining up a weld. 3 miles from the nearest OHLE.

Or seeing the welder thrown backwards through the air by his bodies reaction to the current running through the rail.

We were supposed to bond out the gap between the rails while welding, but the bonds were usually worn out or damaged by being used as tow ropes when the gang buses got bogged down in a muddy access.

 

[Darren R]

I can confirm that some of the stuff mentioned in http://www.theboltonnews.co.uk/comment/comment/yourview/9955329.Full_steam_ahead_for_improved_rail_links/ is true, particularly after this led to a visit by the Hon. Mr Straw to the local headquarters of a certain national railway infrastructure company, just for a chat you understand.

Initial study suggests that your narrative is probably right - just Blackburn side of Sough to just Darwen side of the M65 bridge.

The key point is that a longer loop gives more opportunity for two services to pass each other, allowing those services' times to be adjusted to better fit into the surrounding routes' traffic patterns, e.g. Manchester-Bolton, Preston-Blackburn, etc.

That's very interesting - thanks for the info. I had heard about the Right Honourable and Learned Gentleman popping in for a little chat - and dismissed what was reported in the local press mainly because it was all chatter from MPs and Councils! A genuinely new experience; discovering that what a politician said was actually (fairly) true!

It might prove to be a little more than "just a subtle piece of double track re-instatement" though. Among other things, work done by NetworkRail just two years ago to shore up a retaining wall above the track will have to be removed - it's been built on the formation of the second track!

Good news for the line though - it will greatly improve reliability. Long waits at both Darwen and Bromley Cross for the single track section are a more or less daily occurrence.

Looks like I'm in for a lot of sleepless nights while it happens though!