1
Presented to AASHTO T‐8, June 13, 2017
AASHTO AS 13‐0024Support for the HSCOBS Technical Committee on Moveable Bridges (T-8) in a Technical Advisory Role for Specification Updates – Span Lock Design Study
By James M. Phillips III, PEHardesty & Hanover, Tampa, FL
2
Double‐Leaf Bascule BridgeSpan Locks
STUDY TEAM Hardesty & Hanover, LLC
• Jim Phillips, PE – Research Lead• Rafal Wuttrich, PE – Lead Finite Element Modeling
• Steve Mikucki, PE – Peer Review AECOM (formerly URS and E.C. Driver & Associates, Inc.)• Jim Englert, PE – Project Manager• Michael Reponen, PE – Finite Element Modeling
• FDOT• Will Potter, PE ‐ Structures Research – Field Instrumentation and Testing
• District One & District Four Staff – Support and Bridge Access
AGENDA
Review of Study Purpose & Limitations Recommended Revisions to the AASHTO LRFD Movable Highway Bridge Design Specifications:• Dynamic Load Allowance for Span Lock Design
• Edge Loading / Contact Stresses in Span Lock Design
Other Observations
PURPOSE OF STUDY
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Improve AASHTO LRFD Movable Highway Bridge Design Specifications
Determine appropriate impact factors
Quantify the effects of operating clearances and wear
Quantify the effects of bascule span deflection
Photo 3 & 4 – Span Lock Housing (Left) and Bushing (Right) exhibiting severe wear of the turned bolt holes. Cortez Bridge, Manatee County, FL, FDOT District One; (December 2014, Hardesty & Hanover, LLC)
Understand Why Span Locks are Such a Maintenance Problem
SCOPE LIMITATIONS
Double‐Leaf Trunnion Bascule Bridges
Lock Bar Type Span Locks
DYNAMIC LOAD ALLOWANCE
7
Primary Objective: Determine appropriate Dynamic Load Allowance for use in design and evaluation of span locks
Methodology: Measure strains for slow rolling load (static equivalent)
Measure strains for same load at 30 mph (dynamic load)
Utilize maximum range of strain rather than independent positive or negative values
Calculate dynamic effect as ratio of dynamic to static range of strain
Calculated Dynamic Ratio = , ,
HILLSBOROUGH AVE. BRIDGE SPAN LOCK INSTRUMENTATION & TESTING
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Bridge Section
Main Girder Elevation
Span Lock Bar
HILLSBOROUGH AVE. BRIDGE SPAN LOCK INSTRUMENTATION & TESTING
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Bridge Section
Main Girder Elevation
ReceiverRear
GuideForwardGuide
HILLSBOROUGH AVE. BRIDGE ‐ SPAN LOCK INSTRUMENTATION & TESTING
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Strain Gauge Locations (14 Each Span Lock)
Gauge Locations• Top & Bottom
of Bar between Rear Guide and Forward Guide
• Sides of Bar above and below neutral axis
• Each Face of Forward Guide and Receiver
HILLSBOROUGH AVE. BRIDGE SPAN LOCK INSTRUMENTATION & TESTING
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FDOT Test VehicleTest Vehicle with 30 Block Loading
Axle P1 P2 P3 P4 P5
Load (P)(kips) 10.0 11.7 11.7 37.5 37.5
Test Vehicle with 18 Block LoadingAxle P1 P2 P3 P4 P5
Load (P)(kips) 10.1 10.5 10.5 26.3 26.3
HL-93 VehicleAxle P1 P2 P3 P4 P5
Load (P)(kips) 8.0 16 16 16 16
HILLSBOROUGH AVE. LOAD TEST
12
Sunrise Blvd. Bridge, 30 MPH Test Inside Lane, 30 Block Load
13
-200
-150
-100
-50
0
50
100
150
200
160 11
917
823
729
635
541
447
353
259
165
070
976
882
788
694
510
0410
6311
2211
8112
4012
9913
5814
1714
7615
3515
9416
5317
1217
7118
3018
8919
4820
0720
6621
2521
8422
4323
0223
6124
2024
7925
3825
9726
5627
1527
7428
3328
92
Test 2 (Slow Roll) vs Test 5 (30 MPH)North Lock Bar Strain
18 Block Load, Outside Lane
N-1 T5 N-2 T5 N-1 T2 N-2 T2
Peak Strain Static vs Dynamic Comparison at Top of Lock Bar
Gauge Location
Peak Static Strain (T/C)
Peak Dynamic Strain
RatioDynamic/Static
N-1 Peak 143/75 170/113 1.18/1.51
N-1 Range 218 283 1.30
N-2 Peak 76/150 116/175 1.53/1.17
N-2 Range 226 291 1.29
Comparison of Strains in the Adjacent Lock Bar
Max. Measured Stress Range = 8.4 ksi(not measured at the location of max. stress
N‐1 is Located on Top of Lock Bar N‐2 is Located on Bottom of Lock Bar
HILLSBOROUGH AVE. BRIDGE SPAN LOCK INSTRUMENTATION & TESTING
‐150
‐100
‐50
0
50
100
150
MicroStrain
Time Interval
Test 2 (Slow Roll) vs Test 5 (30 MPH)South Lock Bar Strain
18 Block Load, Outside Lane
S‐1 T5 S‐1 T2 S‐2 T2 S‐2 T5
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Peak Strain Static vs Dynamic Comparison, Receiver Housing
Gauge Location
Peak Static Strain (T/C)
Peak Dynamic Strain
RatioDynamic/ Static
S-1 Peak 50/25 129/63 2.58/2.52
S-1 Range 75 192 2.56
S-2 Peak 26/57 68/130 2.62/2.28
S-2 Range 83 198 2.39
Comparison of Strains in the Opposite Lock Bar
Max. Stress Range = 5.7 ksiHigher Dynamic Ratio, but lower overall strain
S‐1 is Located on Lock Bar Above NA S‐2 is Located on Lock Bar Below NA
HILLSBOROUGH AVE. BRIDGE SPAN LOCK INSTRUMENTATION & TESTING
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Comparison of Strains in the Forward Guide Housing, Static vs Dynamic
Peak Strain Static vs Dynamic Comparison, Receiver Housing
Gauge Location
Peak Static Strain (T/C)
Peak Dynamic
Strain
Ratio Dynamic/
Static
N-C Peak 7/38 7/59 1.00/1.55
N-C Range 45 66 1.47
N-D Peak 4/18 3/31 0.75/1.72
N-D Range 22 34 1.55‐20
‐10
0
10
20
30
40
50
60
70
1 26 51 76 101
126
151
176
201
226
251
276
301
326
351
376
401
426
451
476
501
526
551
576
601
626
651
676
701
726
751
776
801
826
851
876
901
926
951
976
1001
1026
1051
1076
Guide Strain Comparison Test 2 (Slow Roll) vs Test 5 (30 MPH)North Lock Bar
18 Block Load in Outside Lane
N‐C T5 N‐D T5 N‐C T2 N‐D T2
N‐C and N‐D are Located on Joint Side of Forward Guide
HILLSBOROUGH AVE. BRIDGE SPAN LOCK INSTRUMENTATION & TESTING
SUNRISE BLVD. FIELD INSTRUMENTATION AND LOAD TESTING
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Strain Gauges: Outside Girder Span Lock; Outside Main Girders Tip Rotation via Displacement Transducers Variable Shimming of Live Load Shoe
Displacement Transducers
Main Girder Strain Gauges (Typ.)
Live Load Bearing Shimming
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Hillsborough Ave. Bridge30 MPH Test Outside Lane
SUNRISE BLVD. BRIDGE – CONSISTENCY OF FIELD TESTS
18
‐100
‐80
‐60
‐40
‐20
0
20
40
60
80
100
1 77 153
229
305
381
457
533
609
685
761
837
913
989
1065
1141
1217
1293
1369
1445
1521
1597
1673
1749
1825
1901
1977
2053
2129
2205
2281
2357
2433
2509
2585
2661
2737
2813
2889
2965
3041
Microstrain
Time Interval
Chart E30mph Runs in Outside Lane
Comparison of Strain in Lock Bar for 4 Tests Sunrise Blvd. Bridge Load Tests
18O301 S9 18O302 S9 18O303 S9 18O304 S9
Average Standard Deviation = 5.3
Coefficient of Variation = 2.1% to 8.4%
SUMMARY OF DYNAMIC RATIOS
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Table 7 (Modified) – Comparison of Guide and Receiver Dynamic RatiosFDOT Test Truck with 18 Block Load
BridgeLoad in Adjacent Lane Load in Far Lane
Lock BarForward Guide
Receiver Lock BarForward Guide
Receiver
Hillsborough Ave. 1.17 – 1.50 1.08 ‐ 1.62 1.10 – 1.72 2.08 – 4.43 1.49 – 4.09 2.23 – 3.39
Sunrise Blvd. 1.25 – 1.26 1.20 – 1.88 1.25 – 1.68 1.54 – 2.51 1.33 – 2.97 1.58 – 2.75
Corresponding Maximum Strains
Hillsborough Ave. 333 72 87 284 63 36
Sunrise Blvd. 145 256 66 68 88 33
For Scale Reference: 333 Microstrain ≈ 9.6 ksi
Dynamic Ratio =
RECOMMENDED CHANGES TO AASHTO LRDF MOVABLE
Expand AASHTO Movable, Article 2.4.1.2, Dynamic Load Allowance, to add the following:
“2.4.1.2.5 Span Locks
The span locks of double‐leaf bascule bridges (center locks) shall be proportioned for full live load plus twice the normal live load dynamic load allowance, specified in Article 3.6.2 of the AASHTO LRFD Bridge Design Specifications.”To further clarify the application of this provision to the fatigue limit state, add the
following commentary:
“C2.4.1.2.5
The use of twice the normal live load dynamic allowance for span locks applies to Strength, Service and Fatigue Limit States.”
SPAN LOCK CONTACT STRESSES
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Primary Objective: Quantify the effects of bascule span deflection and end rotation on span lock component contact stresses
Identify span lock component geometries that reduce contact stress, thereby improve durability
Methodology: Assess structural deformations that influence contact stresses
Use Finite Element Model (LUSAS) to evaluate contact stresses in load shoes (aka wear plates) and lock bars
Model Hillsborough Avenue bridge and span lock system
Validate model by comparing predicted with measured field strains
Model various load shoe shapes and evaluate performance
STRUCTURAL DEFORMATIONS ‐ GIRDER ROTATION AT THE SPAN LOCKS
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Sunrise Bridge Tests Included Measurement of End Rotations (Relative Slope Between Leaves)
For the Test Load in the Lane Adjacent to the Instrumented Lock/Girder Relative End Rotation Measured 0.0047 in/in for Static Loading and 0.0053 to 0.0080 in/in for Dynamic Loading
The Calculated Equivalent Slope at a Center Joint for:• Deflection of L/800 = 0.008 in/in• Deflection of L/1000 = 0.006 in/in
Relative Slope
L
Δ
STRUCTURAL DEFORMATIONS ‐ GIRDER ROTATION AT THE SPAN LOCKS
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Summary of Rotation at Center Joint (1000th inch/inch)Sunrise Blvd. Bridge Load Tests
Test Static/Dynamic Load Position Load Shoe Condition Slope18OSR1 Static Outside Lane Tight Contact all four LLS 4.718OSR2 Static Outside Lane Tight Contact all four LLS 4.718OSR3S Static Outside Lane 0.040” Shim NE LLS, 0.015” gap under SE LLS 4.518OSR4S Static Outside Lane 0.040” Shim SE LLS, 0.015” gap under NE LLS 5.018O301 Dynamic Outside Lane Tight Contact all four LLS 5.318O302 Dynamic Outside Lane Tight Contact all four LLS 6.618O303 Dynamic Outside Lane Tight Contact all four LLS 8.018O304 Dynamic Outside Lane Tight Contact all four LLS 6.118O305S Dynamic Outside Lane 0.040” Shim NE LLS, 0.015” gap under SE LLS 6.318O306S Dynamic Outside Lane 0.040” Shim SE LLS, 0.015” gap under NE LLS 6.3
STRUCTURAL DEFORMATIONS – ECCENTRIC LOADING
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Table 5 – Comparison of Guide and Receiver Strains (Microstrain)Sunrise Blvd. Bridge Load Tests
Load Position
Forward Guide Receiver
Top Gauges Bott. Gauges Top Gauges Bott. Gauges
Back Side
Jt. SideBack Side
Jt. Side Jt. SideBack Side
Jt. SideBack Side
Outside Lane
43 187 47 188 64 44 48 44
Middle Lane
36 123 36 130 39 54 44 31
Inside Lane
28 69 28 82 19 31 26 20
Measured Strain Variations Confirm Eccentric Loading Effects
LOAD SHOE / WEAR PLATE SHAPE
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Contact Stresses at the Lock Bar interface with the Wear Plates or Load Shoes are influenced by the Geometry and System Deformations
System Deformations
Lock Bar Contact Stress
Load Shoe Contact Stress
Modeled with 0.006 in/in relative rotation
LOAD SHOE / WEAR PLATE SHAPE
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Flat shape with radius on leading edge: 13.5 ksi contact stress Eccentric contact on edge of shoe
½”R
LOAD SHOE / WEAR PLATE SHAPE
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Round shape w/ large radius (72”): 16 ksi contact stress Minimal eccentric loading
72” Radius Effective In Reducing Edge Loading
72”R
LOAD SHOE / WEAR PLATE SHAPE
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Compound shape, Flat Center, Radius front and back: 24 ksi contact stress Limited eccentric loading Potential for additional optimization
18“R
RECOMMENDED CHANGES TO AASHTO LRFD MOVABLEAdd the following to Article 6.8.1.5.1, Locking Devices of the AASHTO Movable:
Contact surfaces for span locks shall be designed and detailed to minimize edge loading that may occur due to the deformation of the supporting structure under vehicular loading.
Provide a minimum ½” radius on the leading and trailing edges of contact surfaces subject to edge loading.
Providing a radius on one or more of the contact surfaces should be considered where other means are not available to relieve edge loading.
RECOMMENDED CHANGES TO AASHTO, CONTINUEDAdd commentary for Article 6.8.1.5.1 Locking Devices:
Contact surfaces for span lock systems include wear plates or bushings in the guides and receivers of lock bar type span locks, jaw and diaphragm castings, forgings or shoes, and similar components that function to transfer the load across a joint through a contact stress.
Under the influence of live load, movable spans deflect and the end(s) of the span(s) at the location of locking devices rotates.
For double‐leaf bascule bridges the end rotations of adjacent leaves are additive in relative effect and therefore more significant than for single‐leaf bascule bridges.
RECOMMENDED CHANGES TO AASHTO, CONTINUEDAdd commentary for Article 6.8.1.5.1 Locking Devices:
If the lock system is attached eccentrically to the main longitudinal members, such as on a cantilevered bracket, additional torsional deflection or rotation could take place. If these deformations are not accounted for, edge loading and eccentric loading of the lock system and supports will result in significant restraint and corresponding structural effects.
Typical clearances provided between lock components (e.g. lock bar and receiver bushing) may be considered in determining the magnitude and effect of edge loading.
Bushings supported on multiple springs that allow the bushing to rotate with the contacting surface, may provide relief from edge loading.
RECOMMENDED CHANGES TO AASHTO, CONTINUEDA radius on the contact surfaces (i.e. a cylindrical surface similar to a typical rocker bearing) is an effective means of accommodating movable span deformation and alleviating undesirable restraint in the span lock system.
Past experienced has shown that providing wear plates or bushings with a radius of 72 inches or smaller across the contact surface provides relief from edge loading of typical deck girder double‐leaf bascule spans. A larger radius may be adequate for stiff bridges, such as those with truss members or single‐leaf spans with smaller end rotations.
Use of a radius results in line contact which must be considered in selecting the lock bar and wear plate materials.
RECOMMENDED CHANGES TO AASHTO, CONTINUED
Additional consideration and analysis may be warranted if a double‐leaf bascule is expected to carry rail traffic as the tolerances for rail alignment may be more stringent than that required for highway or pedestrian traffic.
Comparison of Center Joint Deflections (inches)Hillsborough Ave. Bridge Load Tests
Lock / Load Location
18 Block Truck 30 Block Truck
Static Load Dynamic Load Ratio Static Load Dynamic Load Ratio
North Lock / Adjacent Lane
0.09 0.12 1.31 0.11 0.13 1.20
South Lock / Adjacent Lane
0.08 0.13 1.61 0.11 0.14 1.35
North Lock / Far Lane
0.07 0.12 1.79 0.07 0.12 1.64
South Lock / Far Lane
0.06 0.11 1.89 0.08 0.14 1.88
OTHER KEY FINDINGS OF PROJECT
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Wear of lock components (load shoes or wear plates) results in a general reduction in span lock effectiveness & performance• Measurable increases in differential deflection• Measurable but relatively small changes in strain
WEAR EFFECTS ON LOAD TRANSFER AND LOCK PERFORMANCE
35
Simulated Wear Results on Hillsborough Ave Bridge: Measurable Decrease in Effectiveness of the Locks
Relatively Small Decrease in Lock Bar Strain for Typical Wear (8 to 9%)
Up to 25% Decrease in Lock Bar Strain for Excessive Wear
Significant Increase in Differential Deflection ‐350
‐300
‐250
‐200
‐150
‐100
‐50
0
50
100
150
1 38 75 112
149
186
223
260
297
334
371
408
445
482
519
556
593
630
667
704
741
778
815
852
889
926
963
1000
1037
1074
1111
1148
1185
1222
1259
1296
1333
1370
1407
1444
1481
Strain in M
icroStrain / De
flection inch x 100
0
Time Interval
Chart GComparison of Strain & Differential Deflection For Varying Forward
Guide Clearances at North Lock Bar30 Block Load, Slow Rolling / Hillsborough Ave. Bridge
Strain No Adjust Strain 0.042 Shim Strain 0.130 Shim
Defl No Shim Defl 0.042 Shim Defl 0.140 Shim
WEAR EFFECTS ON LOAD TRANSFER
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Comparison of Maximum Strain Range in the Lock Bar with Shim RemovalHillsborough Ave. Load Tests
(30 Block Truck Load for All Cases)
Lock / Load Location
Clearance at Top Shoe of Forward Guide of North Lock
0.011” 0.052” 0.140”
StrainDynamic Ratio
StrainDynamic Ratio
StrainDynamic Ratio
North Lock / North Lane 429 1.41 383 1.37 334 1.32
South Lock / North Lane 285 2.61 274 2.54 250 2.36
Poorly Shimmed Lock resulted in a measurable (8-9%) but relatively small
reduction Strain in Lock Bar
OTHER KEY FINDINGS OF PROJECT
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Improper Adjustment of Live Load Shoes (aka Live Load Bearings) can have a measurable effect on span lock and main girder strains but relatively small Increase in strain in main girders and span lock components
EFFECT OF LIVE LOAD SHOE SHIMMING
38
Improper Adjustment or Wear of Live Load Shoe Simulated by Inserting a 0.040” Shim Under NE Load Shoe
Table 6 – Comparison of Maximum Range of Strain for Various Live Load Shoe Shim Adjustments
Sunrise Blvd. Bridge Tests
Load Type
Load Position
LLS Condition+(Shim) ‐(Gap)Inch x 10‐3
MicroStrainNorth East Girder Live Load Shoe
Lock Bar @ Center Joint
North West Girder Live Load Shoe
NE SETop of Bar
Bott. of Bar
StaticOutside Lane
0 0 119 109 98 138
StaticOutside Lane
+40 ‐15 129 113 103 134
DynamicOutside Lane
0 0 169 137 123 183
DynamicOutside Lane
+40 ‐15 201 145 128 213
StaticMiddle Lane
0 0 70 65 59 87
StaticMiddle Lane
+40 ‐15 81 69 67 83
DynamicMiddle Lane
0 0 136 102 90 166
DynamicMiddle Lane
+40 ‐15 153 104 93 167
StaticInside Lane
0 0 30 25 22 38
StaticInside Lane
+40 ‐15 34 24 23 33
DynamicInside Lane
0 0 67 63 56 74
DynamicInside Lane
+40 ‐15 69 66 60 66
NE NW
SWSE
0.040” Shim
0.015” Gap
Instrumented Span Lock
Inside Lane
Outside Lane
Poorly Shimmed Live Load Shoe resulted in a measurable (6%) but relatively small Increase
in Strain in the Lock Bar
EFFECT OF LIVE LOAD SHOE SHIMMING
39
Improper Adjustment or Wear of Live Load Shoe Simulated by Inserting a 0.040” Shim Under SE Load Shoe
Table 6 – Comparison of Maximum Range of Strain for Various Live Load Shoe Shim Adjustments
Sunrise Blvd. Bridge Tests
Load Type
Load Position
LLS Condition+(Shim) ‐(Gap)Inch x 10‐3
MicroStrainNorth East Girder Live Load Shoe
Lock Bar @ Center Joint
North West Girder Live Load Shoe
NE SETop of Bar
Bott. of Bar
StaticOutside Lane
0 0 119 109 98 138
StaticOutside Lane
‐15 +40 120 103 94 138
DynamicOutside Lane
0 0 169 137 123 183
DynamicOutside Lane
‐15 +40 186 141 123 193
StaticMiddle Lane
0 0 70 65 59 87
StaticMiddle Lane
‐15 +40 74 66 59 86
DynamicMiddle Lane
0 0 136 102 90 166
DynamicMiddle Lane
‐15 +40 146 110 92 164
StaticInside Lane
0 0 30 25 22 38
StaticInside Lane
‐15 +40 30 23 23 33
DynamicInside Lane
0 0 67 63 56 74
DynamicInside Lane
‐15 +40 70 73 65 91
NE NW
SWSE0.040” Shim
0.015” Gap
Instrumented Span Lock
Poorly Shimmed Live Load Shoe resulted in a measurable (8%) but relatively small Increase
in Strain in the Main Girders
Questions?
40
DYNAMIC EFFECTS
AASHTO Table 3.6.2.1‐1, Dynamic Load Allowance, IM
Components IM
Deck Joints – All Limit States 75%
All Other Components
Fatigue and Fracture Limit State
All Other Limit States
15%
33%
Article 2.4.1.2.4, End Floorbeams, of AASHTO Movable states:
“The end floorbeams of the moving span shall be proportioned for full factored live load plus twice the normal dynamic load allowance specified in Article 3.6.2 of the AASHTO LRFD Bridge Design Specifications.”
Article 6.8.1.5.1, Locking Devices, of AASHTO Movable states:
“Double leaf spans shall be provided with center locks to lock together the toe ends of the spans and tail locks or latches. Center locks shall transfer live load and impact from on leaf to the other.”
AASHTO Dynamic Load Allowance, IM
HILLSBOROUGH AVE. BRIDGESPAN LOCK INSTRUMENTATION & TESTING
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‐60.000
‐50.000
‐40.000
‐30.000
‐20.000
‐10.000
0.000
10.000
20.000
30.000
40.000
1 54 107
160
213
266
319
372
425
478
531
584
637
690
743
796
849
902
955
1008
1061
1114
1167
1220
1273
1326
1379
1432
1485
1538
1591
1644
Microstrain
Time Interval
North Bar StrainVariable Shim of top of North Forward Guide
30 Block Load Applied in Inside Lane
N‐1 No Adjust N‐1 w/0.042" N‐1 w/0.130"‐250
‐200
‐150
‐100
‐50
0
50
100
150
1 47 93 139
185
231
277
323
369
415
461
507
553
599
645
691
737
783
829
875
921
967
1013
1059
1105
1151
1197
1243
1289
1335
1381
1427
1473
1519
1565
1611
1657
Microstrain
Time Interval
South Bar StrainVariable Shim of top of North Forward Guide
30 Block Load Applied in Inside lane
S‐1 No Adjust S‐1 w/0.042" S‐1 w/0.130"
Comparison of Strains in the N&S Lock Bars For Various North Lock Receiver Shim Adjustments
43
Comparison of Strains in the Receiver Housing, Static vs DynamicPeak Strain Static vs Dynamic Comparison,
Receiver Housing
Gauge Location
Peak Static Strain (T/C)
Peak Dynamic Strain
RatioDynamic/Static
N-E Peak 4/23 7/35 1.75/1.52
N-E Range 27 42 1.56
N-H Peak 7/7 7/8 1.00/1.15
N-H Range 14 15 1.07‐10
‐5
0
5
10
15
20
25
30
35
40
1 32 63 94 125
156
187
218
249
280
311
342
373
404
435
466
497
528
559
590
621
652
683
714
745
776
807
838
869
900
931
962
993
1024
1055
1086
Receiver Strain Comparison Test 2 (Slow Roll)vs Test 5 (30 MPH)North Lock Bar
18 Block Load in Outside Lane
N‐E T5N‐H T2N‐E T2N‐H T5
Greater Dynamic Effect on Side Facing Center Joint
N‐E is Located on Joint Side of ReceiverN‐H is Located on Back Side of Receiver
HILLSBOROUGH AVE. BRIDGE SPAN LOCK INSTRUMENTATION & TESTING
