Scanning the cables with P50 aug-sept 2020

sept 2020

Links
Intro
p50 laser scanner
datafiles
Table of measurements (by date) with plots
Table of measurements by location.

Related pages:
Cable tensions from aug-sep20 sag surveys
Computing the tension from a sag survey

Updates:

201029: added scans of T8 platform cables from base of Tower 8.

Intro

Following the 10aug20 failure of tower 4 auxmain north, the 305meter suspension cables were surveyed aug-sept 2020 using the p50 laser scanner (this is also called a sag survey). The platform (tower to platform) and backstay (tower to anchor) were scanned by Felix and I. Each set of cables was scanned separately (a set would be T12platform, T4platform, T8backstay, etc..). We scanned each set multiple times to see if there was a bias that depended on the scanner location.

The P50 laser scanner

Accuracy specs are:

range accuracy	1.2 mm + 10ppm to 270m 3.0 mm + 10ppm 570 to > 1km
Angular accuracy	8" horizontal. at 100m = 3.9mm 8" vertical
max sampling resolution	.8mm at 10m for ranges <= 270km 1.6mm at 10m for ranges > 570 meters This sets the density of sampled points

Scanner coordinate system

y axis = azimuth 0 of scanner.
x axis = 90 deg east of y axis
z axis = gravity vertical. positive it up.
the x,y,z coordinate system is right handed.
We did not bother to set azimuth 0 during the observations, so the y axis can be arbitrary.
The scanner was set to compensate for any tilt errors.
When scanning we normally selected a subset of 360 degrees az and -55 to 90 deg elevation.. to limit the time and size of the files.

Datafiles:

The files from the p50 scanner were input to windows using Leica cyclone software. They were then converted to .las (LASer) files and moved to the linux machines.

The file sizes vary from 14Mbytes to 4.8Gbytes.
The current locations of the files are: /share/megs2_u1/phil/data/leica_p50/yymmdd/las/
The measurement table has a link to each .las file.
The .las files are only accessible from the local ao net.

Table of measurements

The table below has an entry for each set of p50 cable measurements. It contains:

date, cables scanned, scanner location, number of points, file size.
link to .las file for p50 data (only accessible from local AO net)
scanner setup used : maxRange mode, sensitivity, and sampling resolution.
filename, notes
Tension plots:

The vertical scan is kips
the horizontal scale is cable index number

1 - first aux cable, 2 to n-1 main cables, then last aux cable
The aux cables are labeled north,south,east,west to orient the numbers
Looking down at the x,y plane the first index is the cable farthest ClockWise. The numbers then increase moving counter clockwise (t4 cable 1 is south aux).

the pink and blue dashed horizontal lines show the operating load for the aux and main cables (from the drawings).
The dashed vertical purple lines delimit the main cables.
The lower left prints the tension in each cable . name format : Tnn(B/P)1..n(A/M) B= backstay, P=platform, A=aux, M=Main).
The middle right prints the break load for the aux and main cables.
The upper right has the p50 maxRange and sampling resolution.06

Notes on some of the measurements

06nov20: T4 main cable south breaks
Note1: 200828 t4platform. We used 120m maxrange so the scanning did not make it to the platform
most of the measurements were taken from one side of a cable set..

eg: south rimwall shooting T8 platform cables.

In this case the North aux Cable was partially blocked by the platform (while you could see all of the south cable.)
We would then repeat T8 platform cables from the north rim wall where the south Aux cable was partially blocked and you could see all of the north cable.

08oct20: have not yet processed:

catwalk tower to platform cables
tiedown 4,8 vertical cables. these will show the platform rotation (since they have tension and are connected to the td jacks).

**sag survey measurements**
date	cables	scanner location	Npnts	filesize	link to file	scanner setup	filename	Notes	Tension plots
200814	t12 backstays	West of cables by sband power supply building.	94,374,489	1.8GB	.las	maxRange:120m sensitivity: normal res:1.6mm@10m	t12b_200814.las		(.ps) (.pdf)
200828	t4 backstays	base of tower looking up at backstays a little to the south of the centerline	20,870,664	399MB	.las	maxRange:120m sensitivity:normal res:.8mm@10m	t4b_200828_clipped.las		(.ps) (.pdf)
*200828	t4 mains	base of tower looking up at mains. a little to the south of the centerline.	2,401,671	46MB	.las	maxRange:120m sensitivity:high res:1.6mm@120m	t4p_200828.las	note1:* did not reach the platform since we has 120m maxrange. redid 200901,200902	(.ps) (.pdf)
200831	t12 mains	visitor center balcony looking south , a little west of centerline	15,314,540	293MB	.las	maxRange:270 m sensitivity:normal res:.8mm@10m	t12p_200831.las	did not get the end of the aux cable on the platform side. redid 200902,04 from east and west side.	(.ps) (.pdf)
200901	t4 mains	same location as 200828	12,075,977	231MB	.las	maxRange:270m sensitivity:normal res:.8mm@10m	t4m_200901.las	did not get the end of auxmain. redid 200902 from rimwall.	(.ps) (.pdf)
200901	t8 mains	rim wall sw-01. looking north almost at e/w center of platform.	18,397,989	351MB	.las	maxRange:270m sensitivity:high res:.8mm@10m	t8m_200901.las	did not get platform end of t8auxN (platform hid). redid from north side 200903.	(.ps) (.pdf)
200902	t4 mains	rim wall se-01. looking north almost at e/w center of platform.	13,009,051	249MB	.las	maxRange:>1km sensitivity:normal res:1.6mm@10m	t4m_200902.las	got all cables (since auxmain4N is gone).	(.ps) (.pdf)
200902	t12 mains	rim wall NW-04. looking east almost at n/w center of platform.	15,512,363	296MB	.las	maxRange:>1km sensitivity:normal res:1.6mm@10m	t12m_200902.las	shot from west side of dish to get all of auxmain12-W.	(.ps) (.pdf)
200903	t8 backstays	below backstay cables close to top of road.	255,660,850	4.8GB	.las	maxRange:120m sensitivity:high res:.8mm@10m	t8b_200903.las	very large file because we did 0-360 in az and 0-90 in elevation.	(.ps) (.pdf)
200904	t12 mains	east side of rim wall looking west. az=85 at distomat 2.	9,946,295	190MB	.las	maxRange:>1km sensitivity:normal res:1.6mm@10m	t12m_200904.las	shot from east side. Tried to get all of t12AuxMainE but az arm blocked some of it.	(.ps) (.pdf)
200904	t12 catwalk	east side of rim wall looking west. az=85 at distomat 2.	9,946,295	190MB	.las	maxRange:>1km sensitivity:normal res:1.6mm@10m	t12m_200904.las	same file at t12mains	catwalk plots
200904	t12 catwalk mid cable	east side of rim wall looking west. az=85 at distomat 2.	9,946,295	190MB	.las	maxRange:>1km sensitivity:normal res:1.6mm@10m	t12m_200904.las	same at t12mains file this is the cable to the midpoint of catwalk	catwalk plots
200915	t12 backstays	from the helipad	1,717,397	33MB	.las	maxRange:>1km sensitivity:normal res:1.6mm@10m	t12b_200915_hpad.las	tried t12backstays from helipad and base of tower 4 .	.ps) (.pdf)
200915	t12 backstays	from the base of tower 4	1,105,543	22MB	.las	maxRange:>1km sensitivity:normal res:1.6mm@10m	t12b_200915_t4.las	both were a long shot.	(.ps) (.pdf)
200915	t4 backstays	from the helipad	4,856,766	93MB	.las	maxRange:>1km sensitivity:normal res:1.6mm@10m	t4b_200915.las	check if 200828 shot from under the cables is biased. (not much)	(.ps) (.pdf)
200915	t8 mains	from nw-05 rim wall looking south toward cables.	3,087,595	59MB	.las	maxRange:>1km sensitivity:normal res:1.6mm@10m	t8m_200915.las	shot from the north side to get auxmain8N better.	(.ps) (.pdf)
200915	t8 catwalk	from nw-05 rim wall looking south	3,087,595	59MB	.las	maxRange:>1km sensitivity:normal res:1.6mm@10m	t8m_200915.las	same file at t8mains	catwalk plots
200915	t8 backstays	from the base of tower 4	708,129	14MB	.las	maxRange:>1km sensitivity:normal res:1.6mm@10m	t8b_200915.las	This was another long shot	(.ps) (.pdf)
200916	t4 mains	from helipad	4,990,131	96MB	.las	maxRange:>1km sensitivity:normal res:1.6mm@10m	t4cw_200916.las	got t4mains and t4 catwalk cable in 1 file	(.ps) (.pdf)
200916	t4 catwalk	from helipad	4,990,131	96MB	(see t4m)	maxRange:>1km sensitivity:normal res:1.6mm@10m	t4cw_200916.las	got t4mains and t4 catwalk cable in 1 file	catwalk plots
201021	t8 platform	from road at base of tower 8	35,619,092	172MB	.las	maxRange>1km sensitiviey:normal res:1.6mm@10m	t8p1km_201021.las	discontinuity at x=0 (el=90deg:overhead)	(.ps) (.pdf)
201021	t8 platform	from road at base of tower 8	76,816,381		.las	maxRange>270m sensitivity:high res:1.6mm@10m	t8p270m_201021nh.las	discontinuity at x=0 (el=90deg:overhead	(.ps) (.pdf)
201106		T4 Main Cable south Breaks
201111	T4 platform	from west edge of helipad	21539287 (preclipping)	47MB	.las	maxRange>1km res:1.6mm@10m	t4p_201111.las	i clipped out the bushes has T4 platform t12 plat:mainsshadowed t12 backstays	(.ps) (.pdf)
201111	T4 platform	from east edge of helipad	22241431 (preclipping)	41MB	.las	maxRange>1im res:1.6mm@10m	t4b_201111.las	clipped out bushes has: t4Backstays t4platform t12platform(shadowed) t12backstays	(.ps) (.pdf)
201111	T4 backstays	from east edge of helipad	22241431 (preclipping)	41MB		maxRange>1im res:1.6mm@10m	t4b_201111.las	same file as T4platform from helipad east	(.ps) (.pdf)
201111	t12backstays	from west edge of helipad	21539287 (preclipping)	47MB		maxRange>1km res:1.6mm@10m	t4p_201111.las	same file as 201111 t4 platform west	(.ps) (.pdf)
201111	t12backstays	from east edge of helipad	21539287 (preclipping	47MB		maxRange>1km res:1.6mm@10m	t4b_201111.las	same file as 201111 t4 platform east	(.ps) (.pdf)
201124	t12backstays	road before vc looking south		13Gb	.las		t12b_201124.las	to see where backstays would fall
201201		platform collapses
201203	platform in dish	from helipad		370MB	.las	maxRange 570m res:.8mm @10m	pltlow_201203.las
201209	T12 south face	from VC balcony		2.2GB	.las	maxRange 120m res:.8mm@10m	t12_201209.las	check if tower is tilted
201223	T12 North face	from road next to VC		166MB	.las	maxRange	t12_201223_clipped.las	check if tower tilted. Removed road.
201228	T4 NorthFace	From SE edge of helipad		66MB 63MB	.las .las	maxRange:270m res:.8mm@10m	t4_201228.las t4_201228_clipped.las	all data try to remove ladder

Processing: /share/megs/phil/x101/p50/20mmdd/location/proccableall.pro, for processing each days data.

Measurement sets by location

This shows the measurements done at each location:\

location	filename	notes
T12 mains	t12p_200831.las	didn't get to end of aux cables on platform
	t12m_200902.las	got all of auxmain12W
	t12m_200904.las	got most of auxmain12E
T12 backstays	t12backstay_1.6mm.las	from the sband power supply building. close to cables
	t12b_200915_hpad.las	from the helipad. long shot
	t12b_200915_t4.las	from the base of tower 4 (longer shot:)
	t4p_201111.las	from west edge of helipad
	t4b _201111.las	from east edge of helipad

T4 mains	t4p_200828.las	shot in 120 m max range. didn't make it all the way to the platform
	t4m_200901.las	reshot from 200828 location in 270 m max range.
	t4m_200902.las	from south rim wall. got all of t4auxmainS.
	t4p_201111.las	from west edge of helipad
	t4b_201111.las	from east edge of helipad
T4 backstays	t4b_200828_clipped.las	under the cables from the base of tower 4.
	t4b_200915.las	from the helipad
	t4b_201111.las	from helipad east side.

T8 mains	t8m_200901.las	from sw-01 rim wall. got all of t8auxmainS.
	t8m_200915.las	from nw--05 rim wall looking south. got a good shot of t8auxmainN
	t8p1km_201021.las	from road in front of T8 base. 1km max range
	t8p270m_201021.las	from road in front of T8 base. 270m max range.
T8 backstays	t8b_200903.las	from under the cables. really big file.
	t8b_200915.las	from the base of tower 4. long shot.

 home_~phil