1986 - Page 25
Underground in Top Hard seam the state of the surveying bases and practice was practically non-existent.
An old system using 5 spads or pins in line was used as a bearing base and when laid up (advanced further inbye) a further set of 5 pins in line was established by surveying inbye by a dial, no theodolite having been used inbye for the past several years until needed for the large traverse. (A spad is a type of flat nail with a hole in for threading string or wire through to hang down when weighted either by plumbob or piece of bind).
The distances between the bases were just loosely ground taped by linesmen using a Silverline 100 feet steel tape and several of these distance when checked were erroneous as no check-measuring was ever done whilst laying up the bases.
There were no centre pins for direction in any gate in the pit. That is the system used to control direction accurately and of course that was the method I was taught and I thought was used at all collieries.
The system in practice was to accept the best of the last 10 chalk marks and project them forward to the last arch with a piece of chalked millband flapped on the arches. Of course movement of the arches when the weight comes on as the face advances causes the arches to contort or sink and in doing so the chalk marks moved accordingly. Only chalk marks haphazardly marked on the majority of arched girders in every gate denoted where the centre line was supposed to be and a general glance along most of the gates told me that most were veering off line.
Initial setting out of new development was done by this method and invariably off bent centre lines to start with! After surveying every working panel gate in the pit and establishing proper centre pins and good solid white lines I found that every gate was in error, some by a matter of 10 minutes and 20 minutes and up to 30 minutes of arc but one Loader gate (57s) was 3 degrees of arc off from the planned direction. (As previously stated 1 minute subtends 1 inch in 100 yards therefore 3 degrees is 180 minutes therefore the gate was 180 inches or 15 feet (4.56m) out of planned position).
Gradually easing these gates back onto true line took a few weeks but 57s took several months and a large bend is apparent on the plan. I had a word with the belt men who were able to run the conveyor belt round the bend by angling the rollers. No problems were encountered as careful checks by them kept the job running with no spillage.
A major trunk belt on 25s kept turning over and twisting when empty. Just by eyesight it was apparent to me that the gearhead was out of line and twisted so I took measurements and sights etc using my oil lamp and the Manager’s and Deputy Manager’s oil lamps as they just happened to be passing by at the time. I plotted the results on a large scale and stretched on the Conference Room table and by lining in using a reel of cotton it showed what I had stated was correct.
Engineers Wilf Pearson and Deputy, Fred Marples Belt man and Belt Overman, Manager Dave Rodden, Undermanager Jack Taylor and Deputy Manager David Oliver were there to see. They were very dubious to start with but Dave Rodden the Manager ordered the gearhead to be moved into line some 2’ 6” (0.76m) that night. The conveyor belt then ran perfectly after that and I got another ‘star’. It was only commonsense really for anyone to see if they had looked.
Some gates did have side crush and floor lift and these were measured and the various types of byework recorded. In fact I kept a plan of the pit with every type of support and lengths plotted in every gate. This type of information was asked for on occasions for statistical records, so updating it periodically with the various supports and sizes set made this easy. Some gates were dinted or lined with other arches inside the old twisted ones but this reduced the size of the gate.
Various arches and sizes were experimented with and the local firm Hollybank supplied flat tops where the legs were set in line with the old rings and dirt packed over the top.
Other gates were skinned and others were back ripped which meant that the old distorted arches had to be taken outbye, some to be re-straightened for re-use and some to be sent out and others to be gobbed in old gates. Of course all these actions required careful planning to allow supplies trams to pass. Failing that, materials were reversed up the Loader gate conveyor to the face and some transported by various means to the Supply or Air gate.
Dr Whittaker from the University advised that we introduce 16/17 x 12 ft arches instead of the 15 ft x 10s usually set and after trials even with floor lift and side crush they were found to be better and they became the norm for all gates. There were no surveys taken through a finishing line on any panel to check the line of the face or couple up the bases in both gates.
When I first went to Ollerton there were complaints about lack of lines every week, but not anymore. A proper system was established where lining was done in every gate twice a week or once if slower advance.
Measurements up each gate were again haphazard and every one erroneous, because odd distances in feet and inches on the last arch were used as a base for the following measurement and that could be on any week day and the weekend measurement required was projected by the number of cuts taken at the face irrespective of the thickness of the cut.
These measurements were added up down the pit by the linesmen and the distances recorded on a loose leaf of lined paper along with the line report as to whether the gate was on line relevant to their line. That only made things worse as the line was wrong to start with and any action taken to correct the gate direction could have been the wrong way, as I was to find out.
The lowest wrong measurement up a gate was about 3 feet (0.9m) to the worst that was 16 feet (4.9m) too far.
Over the next few weeks I had to do the one thing that surveyors should not do and that was to ‘wangle’ the measurements.
At all the panels working I had to hold some of the true measurement back until we reached parity then all future measurements were then correct and I insisted on it.
The men had been paid for the measurements given but they of course were wrong so they had been paid for yardage not done. However try telling that to an Official or Chargehand or Union man. That is why I did what I did.
No-one ever found out and once each gate had proper measure marks, firstly 100 feet marks then later after May 1976 when we went metric I had measure marks established every 10m from the centre of the shafts down every open roadway and from every gate junction up every panel gate and cross-checks were made by reading a measurement off at a theodolite or dial mark that had been accurately measured to.
I got the Line lads some weekend overtime shifts to do this. It not only established a proper accurate system of measuring but helped me in the long term because fewer and fewer questions were asked as to where something was because everybody from the Manager down, the Undermanager, the Underofficials and other department members used these marks and they all knew where they were. For example when a door, cloth, fire bucket, hydrant, manhole, methane hole, engine and return wheel or electrical switch was installed that measurement was used and notified to us then Dougie Stockham my Supervisory linesman (later Surveyor’s Assistant WPIS) would arrange for one of the linesmen to check up the mark to make sure. 99% of the time what the other departments had told us was correct. The system worked. It saved us hours of work after the initial hard graft.
Theodolite surveys were done personally by me up every gate and measurements were done using the string catenary measuring system.
Strings or wires weighted down by a lamp or piece of bind suspended from clips were lined in horizontally and vertically to the heights noted on the theodolite survey, then a twist of wire lined in vertically on the temporary marks that were on the sight line between the theodolite stations and the 50m steel band anchored at one end with a 20lb pull exerted at the other a reading in metres and parts of metres taken at each end. The difference between the two readings gives the distance.
By using the band on the other side marked in feet and inches a simple pull tight and read from zero at one end gave a total distance that when converted to metres gave an immediate check on the catenary measuring just done. This ensured that no major mistake had been made. The system continued until all lines were measured.
Statutory surveys for every 100 yards later 100m advance (only quarter end face lines were drawn on the plan previously albeit that the line was way beyond the 100 yards mark) were carried out using a dial with measurements using 20m steel tapes and periodically say every 500m overlapped and checked using a theodolite to lay up a new base and so on until the face finished when a survey was carried through the face from one base in the Airway to another base in the Loader Gate and accurate measurements taken to the face line.
This would show whether a face was bent or not and if it was bent it was plotted as bent but every face line on the plans before I went there was drawn straight! On main road traverses measurements were still done in catenary but read off to brass bosses with cross marks (carrots) on fixed dial tripods in line with vertical angles being taken both directions at each alternate theodolite station.
By a series of calculations and adjustments accurate co-ordinates for each underground theodolite or dial mark and face line or heading position was obtained and plotted on the plan of the mine that was on 1/2500 scale used by the Ordnance Survey.
These marks could be overlaid by the Ordnance plan directly using the same grid as the underground was correlated to the surface so you knew where you were relative to the two.
As I progressed through the mine, spending 3 and sometimes 4 days a week down the pit on jobs I began to get co-operation from many, particularly Deputies and Overmen who could see the transformation, so much so that Eric Barton Development Overman used to call to see me at least a couple of times a week then to make sure that the developments were to plan, particularly where junctions were being built or gate end curves were being driven. The Assistant Undermanager in charge of development on the Day shift would call in almost every day, I used to think it was mainly to have a cup of tea and a chat.
The reason for going to Ollerton in February 1971 was to do a check survey of a 5½ mile long thirling survey from the North side of the pit to the East side.
It was planned to connect the 2 sides of the pit by means of a long heading driven from both sides at an angle towards one another.
Two panels had stopped short due to increasing dirt thickness and originally had been planned to thirl the gates from one panel to the other at right angles by simply driving from one end only in the 2 gates that were planned to connect.
To rationalise the conveying system, coal from North side panels would be conveyed via this new connection to the East side trunk conveyors thus allowing the North side trunk conveyors to be defunct and release several gearheads and button men (conveyor attendants) for other jobs.
It had taken the previous Ollerton survey team about 4 months with several days in the week and almost every weekend to survey round from one side to the other and a heading was set off from the East side.
When I went down the pit on my second day there with the theodolite to check the heading that had just started for bearing I was aghast to find that it was way off line. There were no line pins but chalk marks in the centre of the heading that was now about 20 yards (19m) in. The angle turned out unfortunately was off a bent gate, there was eyesight in it. The true bearing turned out was 1’ 8” (0.5m) off these centre marks.
To make sure I was correct I went outbye again for 4 stations and assuming that the bearing for that base was correct as done by the previous team (it was) I surveyed back into the heading after about an hour. The line I had established was correct.
I stopped the job, told the Deputy and workmen not to go forward anymore but to back track and cut out and pull all the arches set onto the new line. Of course the Deputy had to ask permission and the Manager was informed. However when I got out of the pit I explained to the Manager the problem.
Keith Houghton (2473) the Surveyor became progressively ill and fell off work leaving me as the only qualified surveyor at a million ton a year pit, one of the biggest in North Nottinghamshire . I didn’t complain about it I just got stuck in.
The only time Area staff visited after that survey was to see how I was coping!! Keith eventually returned to work quite some time later by transferring to the Subsidence department with Charlie Shadbolt (2499) at Eastwood Hall.
I had one Apprentice and three out of six idle and belligerent linesmen.
David Rodden, the Manager, agreed that if I was right with the new line the rings had to be pulled over. They did realign most of them but there was still a kink at the turn point because the heading had to go ‘forwards not backwards’ they said.
We managed to measure the total 5 miles plus by leg catenary using a 50m band in 5 day shifts in the week even negotiating main roads with haulage teams, a paddy road that had several journeys and a deep swilley full of water.
Trying to train the others on the team plus 3 Group Surveyors who had not experienced this system before was painful and we achieved between ½ and ¾ mile the first day and I thought I had anticipated wrongly and would have to eat humble pie and be ridiculed, however on the next shift it seemed to click in with about a mile measured and well over a mile on the following two days with over 1½ miles on the fifth day to complete the job.
The theodolite angling of 61 survey stations was completed in 5 days on the day shift during February 1971 and after calculating and re-checking the nasty short steep sight of about 16’ 6” (5m) through a hole in an overcast it was agreed to alter the bearing to the North side by just over one minute of arc. (Note one minute subtends 1 inch in a 100 yards, therefore in the distance round to the North side 42s end could have been up to 1’ 7” (0.48m) out on thirling).
This sighting was to give the shortest distance between the 2 sides of the pit as to go round by other roads would have added another 2 miles or thereabouts.
(I did survey that route later right back to the pit bottom base line).
Plotting the survey after calculating the values proved that certain parts of the pit had not been plotted correctly in the past and replotting of some of the roadways had to be done and a brand new sheet was constructed by me and after checking every roadway where possible by Bocking protractor using angles for the bearing calculations and measurements taken from the survey book of the infrequent dial surveys of the past sooner than using the conversion calculations from the old Dunnose grid to the metric grid.
Quite a few of the roadways were plotted wrongly but I finally felt that the new positions that I had plotted on the new sheets were correct. It would appear that no survey using a theodolite had been carried out in the previous 13 years.
On 16th October 1971 the headings thirled but not before giving me a fright thinking that I was terribly wrong when a borehole from the 42s North side heading missed the 25s East side heading by what I estimated about 1 foot or 0.3m. I could hear the drill rod spinning round and see bitting on the face of the heading at the left hand side.
Not having been round to the North side prior to thirling I was unaware that the pilot head I had requested in the middle of the gate had in fact been done at the left hand side of the gate and also behind the line of the arches.
The Overman Cliff Meakin knew that this snicket had gone off line to the left so he had the borers drill a hole at 45 degrees to the right.
Of course it missed the gate.
I was not to know this of course and I came out of the pit, bathed and went home early feeling utterly dejected and thinking that if the thirling had missed by the width of the gate then I was finished...the sack.
I couldn’t sleep that night and went to work early next morning to be told that there was a hole through and it was clothed off to ease the ventilation.
I got changed sharpish, went to the pit top got the banksman to organise a special ride for me between the materials runs and I ran inbye to 25s East side end which was nearer to the pit bottom.
David Evans, head linesman and me did offset line work through the bent snicket and after adding up and taking away the measurements of the offsets I realised that it was possibly about 4” (0.10m) or 5” (0.13m) out of line. Absolutely spot on to the layman.
The Manager David Rodden wanted to see me they said when I got out the pit and I was told that I was to see him ‘before getting bathed’ although I was as black as the ‘Ace of Spades’.
He was elated by the news and said that ‘he had always had faith in me’. He sat me down and poured me a double dram of whisky from a bottle of Scotch in the cupboard behind his desk. ‘I’ll have one as well’ he said.
I had made my mark and whatever I wanted in future I got and co-operation from practically everybody at the pit was phenomenal! I think they all thought that the headings would miss. They would have missed if that line had not been changed. What a relief.
When the heading had been completed properly a few days later I lined through from one side to the other and the ‘error’ was ½” (0.01m) in alignment and after surveying through by theodolite and coupling up the bases was to a few seconds of arc and the catenary measuring about 6” (0.15m) in distance or 1 in 58,000. It proved that the system of measuring I had been taught at Teversal was as good as you can get. Even a modern EDM Total station theodolite would only give about the same accuracy.
Several Area staff including Joe Callinan the Planner and Production Manager visited the site. I think they all thought I was telling tales.
42s side and 25s side had to be marked on the arches to show where the headings had joined as the point was not noticeable otherwise other than the distance between the last 2 arches set was only about 2 feet (0.61m) instead of 3 feet (0,91m).