combatreform.org/WHEELSVSTRACKS

1. Wheels/Tracks
NRMM Study
US Army Corps
of Engineers Engineer Research & Development Center

2. Purpose
Demonstrate Mobility Modeling methodologies
that assist in assessing vehicle-terrain interaction.
Scope
Use Mobility Modeling to identify vehicle
parameters and terrain features that impede mobility.
Forecast mobility over different mission areas of
interest.
US Army Corps
of Engineers Engineer Research & Development Center

3. Vehicle Field Testing Mobility Modeling and NRMM
Component Level Modeling
Swim
Obstacle Crossing
Concept Vehicle Evaluation
TERRAIN DATA
VEHICLE DATA –Soil Type
–Dimensions –Slope SCENARIO
–Power Train –Vegetation Type –Weather
–Weight –Obstacle Type DRIVER –Climate
–Dynamics/Shock –Urban Code –Visibility –Commander’s Intent
–Gap Width –Reaction Time
– –Water Depth/Velocity
Future Vehicle Technologies
–Shock/Vibration Tolerance –
–Road Type –
–Snow Depth/Density
–
•Mobility Factor Inference/Soil Moisture
Strength Prediction (SMSP)
Surface Roughness Obstacle Geometry
Wetness Index Bank Angle/Height/Vegetation
Soil Moisture/Strength Road Curvature/Grade
Stem-size Spacing Recognition Distance
Off-Road On-Road Gap Crossing
Stochastic
VTI Algorithms - Robust Mobility Modeling (RMM)
Agility Mobility
Soft Soil NATO Reference Mobility Model (NRMM) Modeling
(SMM)
Vehicle Performance Information
Products
US Army Corps
of Engineers Engineer Research & Development Center

4. Mobility Modeling and NRMM
Applications
• Current Vehicle studies
Future Scout Vehicle - PM FSV
Medium Brigade Wheels/Track Study - DARPA
• Acquisition
FMTV HML
AAAV HMMWV
• Command and Control/ Tactical Systems
DTSS CTIS
TEM JMTK
• Constructive and Virtual M&S
JANUS CASTFOREM
JWARS CCTT SAFOR
US Army Corps
of Engineers Engineer Research & Development Center

5. Mobility Modeling and NRMM
Physics-based concept
Tractive Force Speed Curve
Maximum Traction From Soil
Vehicle Operating Region
Tractive Force
Maximum Speed
Theoretical
Obstacle Force Power-Train
Curve
Vegetation Force
Slope
Motion Resistance
SPEED
US Army Corps
of Engineers Engineer Research & Development Center

7. NRMMII Summary
NRMMII - A computer-based collection of equations and algorithms
designed to predict the maximum steady-state operating capability of a given
vehicle in a prescribed terrain.
Areas
Philippines (Mindanao Island)
South Korea (Eastern Coast)
Kuwait (Northwestern Border)
Germany (Lauterbach)
Scenarios
Dry Normal
Average soil strength and moisture for the 30 driest days in
an average rainfall year
Wet Slippery
Average soil strength and moisture for the 30 wettest days in
an average rainfall year, with rainfall occurring within the last 6 hours
US Army Corps
of Engineers Engineer Research & Development Center

8. Study Areas
Map Code Quad No.
Sea of
Japan
1 2 1
2
NC51-11
NC51-12
NORTH 3 NC51-14
KOREA 4 NC51-15
5 NC51-16
3 4 5 6
7
NB51-2
NB51-3
8 NB51-4
9 NB52-1
1 Gangneung Mindanao 10 NB51-6
Seoul
6 7 8 9 11
12
NB51-7
NB51-8
Yellow 13 NB51-12
Sea Devao
SOUTH 10 11 12
KOREA
13
Hamburg
Berlin
GERMANY
MapCode Quad No.
IRAQ 1 5322
1
MapCode 1
1 5449IV KUWAIT Persian
NEUTRAL
Gulf
ZONE Frankfurt
SAUDI
ARABIA
Munich
US Army Corps
of Engineers Engineer Research & Development Center

9. Slope Distributions for the Four Study Areas
120
> 60%
51 - 60%
26 - 50%
100 16 - 25%
11 - 15%
6 - 10%
80 3 - 5%
% Total Area
0 - 2%
60
40
20
0 Germany Philippines Korea Kuwait
Distribution of slope changes from region to region
US Army Corps
of Engineers Engineer Research & Development Center

10. Surface Roughness (RMS) Distributions for the FourAreas Areas
RMS Distributions for the Four Study Study
120
>= 4.0 in.
3.5 - 4.0 in.
3.0 - 3.5 in.
100 2.5 - 3.0 in.
2.0 - 2.5 in.
1.5 - 2.0 in.
80 1.0 - 1.5 in.
% Total Area
0.5 - 1.0 in.
0.0 - 0.5 in,
60
40
20
0 Germany Philippines Korea Kuwait
US Army Corps
of Engineers Engineer Research & Development Center

11. Soil Type Distributions for the Four Study Areas
Soil-Type Distributions for the Four Study Areas
120
Inland Water
Evaporites
Rock
100 Pt - Peat
OH - Organic Clays
CH - Inorganic (fat) clays
MH - Inorganic elastic Silts
OL - Organic Silts and Clays
80 CLML - Silty Clay/Clayey Silt
% Total Area
CL - Inorganic (lean) Clays
ML - Inorganic Silts
SC - Clayey Sands
60 SM - Silty Sands
SP - Poorly-graded Sands
SW - Well-graded Sands
GC - Clayey Gravels
GM - Silty Gravels
40 GP - Poorly-graded Gravels
GW - Well-graded Gravels
20
0 Germany Philippines Korea Kuwait
US Army Corps
of Engineers Engineer Research & Development Center

12. Speed Profiles for the MTVL and LAVIII in Germany Speed Limiting Reasons in Germany
50 120
MTVL Tipping NOGO
(Dry Normal) Sliding NOGO
Soil NOGO
40 MTVL
100 Obs Override NOGO
Veg Override NOGO
Percent Total Area
(Wet Slippery)
Obs Belly Interference NOGO
Speed, mph
Obs Clearance Interference NOGO
LAVIII 80 Soil & Slope Resistance NOGO
30 (Dry Normal) Inability to Brake NOGO
Dry 60
Unknown NOGO
Tipping on Curves
LAVIII Sliding on Curves
20 (Wet Slippery) AASHO Curvature Spd Limit
External Limit
40 Driver Prudence Over Veg
Obs Override Force
10 Obs Impact Speed
Wet Slippery Mnvr Around Veg
20 Mnvr Around Obs & Veg
Visibility
0 Soil,Slope,Veg Resistance
Tire Speed Limit
0 20 40 60 80 100 0 Ride Dynamics Limit
MTVL (Dry) MTVL (Wet) LAVIII (Dry) LAVIII (Wet)
No Prediction
Percent Total Area The tracked vehicle can operate on Vehicle (Scenario)
significantly more terrain in both
a wet and dry condition
US Army Corps
of Engineers Engineer Research & Development Center

13. Speed Profiles for the MTVL and LAVIII in Philippines
Speed Limiting Reasons in Philippines
50
MTVL 120
(Dry Normal) Tipping NOGO
Sliding NOGO
40 MTVL 100
Soil NOGO
Obs Override NOGO
Both vehicles have similar (Wet Slippery) Veg Override NOGO
Percent Total Area
Obs Belly Interference NOGO
Speed, mph
performance in the dry Obs Clearance Interference NOGO
30 LAVIII
80 Soil & Slope Resistance NOGO
condition (Dry Normal)
Inability to Brake NOGO
Unknown NOGO
LAVIII
20 (Wet Slippery)
60 Tipping on Curves
Sliding on Curves
AASHO Curvature Spd Limit
External Limit
40 Driver Prudence Over Veg
10 Obs Override Force
Obs Impact Speed
Mnvr Around Veg
20 Mnvr Around Obs & Veg
Visibility
0 Soil,Slope,Veg Resistance
0 20 40 60 80 100 Tire Speed Limit
0 Ride Dynamics Limit
Percent Total Area MTVL (Dry) MTVL (Wet) LAVIII (Dry) LAVIII (Wet)
No Prediction
Vehicle (Scenario)
The tracked vehicle can operate on
significantly more terrain in
a wet condition. Soft soil performance is an issue.
US Army Corps
of Engineers Engineer Research & Development Center

14. Speed Profiles for the MTVL and LAVIII in Korea
Speed Limiting Reasons in Korea
50
MTVL 120
(Dry Normal) Tipping NOGO
Sliding NOGO
Soil NOGO
40 MTVL 100 Obs Override NOGO
Both vehicles have similar (Wet Slippery) Veg Override NOGO
Percent Total Area
Obs Belly Interference NOGO
performance in the dry
Speed, mph
Obs Clearance Interference NOGO
30 LAVIII 80 Soil & Slope Resistance NOGO
condition (Dry Normal)
Inability to Brake NOGO
Unknown NOGO
20
LAVIII
(Wet Slippery)
60 Tipping on Curves
Sliding on Curves
AASHO Curvature Spd Limit
External Limit
40 Driver Prudence Over Veg
10 Obs Override Force
Obs Impact Speed
Mnvr Around Veg
20 Mnvr Around Obs & Veg
Visibility
0 Soil,Slope,Veg Resistance
0 20 40 60 80 100 Tire Speed Limit
0 Ride Dynamics Limit
Percent Total Area MTVL (Dry) MTVL (Wet) LAVIII (Dry) LAVIII (Wet)
No Prediction
Vehicle (Scenario)
The tracked vehicle can operate on
significantly more terrain in
a wet condition. Soft soil performance is an issue.
US Army Corps
of Engineers Engineer Research & Development Center

15. Speed Profiles for the MTVL and LAVIII in Kuwait Speed Limiting Reasons in Kuwait
50 120
MTVL Tipping NOGO
The wheeled vehicle had (Dry Normal) Sliding NOGO
Soil NOGO
40 better performance in both MTVL
100 Obs Override NOGO
Veg Override NOGO
Percent Total Area
wet and dry conditions. (Wet Slippery) Obs Belly Interference NOGO
Speed, mph
Obs Clearance Interference NOGO
80 Soil & Slope Resistance NOGO
30 LAVIII
(Dry Normal) Inability to Brake NOGO
Unknown NOGO
LAVIII 60 Tipping on Curves
Sliding on Curves
20 (Wet Slippery) AASHO Curvature Spd Limit
External Limit
40 Driver Prudence Over Veg
Obs Override Force
10 Obs Impact Speed
Mnvr Around Veg
20 Mnvr Around Obs & Veg
Visibility
Soil,Slope,Veg Resistance
0 Tire Speed Limit
0 20 40 60 80 100 0 Ride Dynamics Limit
MTVL (Dry) MTVL (Wet) LAVIII (Dry) LAVIII (Wet)
No Prediction
Percent Total Area Vehicle (Scenario)
US Army Corps
of Engineers Engineer Research & Development Center

16. Example of Evaluation of enhanced System
•NRMM allows for the evaluation of impact of new technologies
•What is the advantage of increasing the engineer power by 100%
•What is the advantage of increasing the ride performance by 100%
Speed Profiles for the MTVL on Dry Condition in Philippines Speed Limiting Reasons in Philippines
60 120
MTVL
PowerX2 Tipping NOGO
(Original) Sliding NOGO
Original PowerX2 Ride/ShockX2 Ride/ShockX2
50 100
Soil NOGO
Obs Override NOGO
MTVL
(Power X 2) Veg Override NOGO
Percent Total Area
Obs Belly Interference NOGO
40
Speed, mph
Obs Clearance Interference NOGO
MTVL 80 Soil & Slope Resistance NOGO
(Ride/Shock X 2) Inability to Brake NOGO
Unknown NOGO
30
MTVL 60 Tipping on Curves
Sliding on Curves
(Power/Ride/ShockX2)
AASHO Curvature Spd Limit
20 External Limit
40 Driver Prudence Over Veg
Obs Override Force
Obs Impact Speed
10 Mnvr Around Veg
20 Mnvr Around Obs & Veg
Visibility
0 Soil,Slope,Veg Resistance
0 20 40 60 80 100 0 Tire Speed Limit
Ride Dynamics Limit
MTVL MTVL MTVL MTVL
Percent Total Area Vehicle (Scenario)
US Army Corps
of Engineers Engineer Research & Development Center

17. Off-Road Performance Summary
Wheel Track
Traction Traction
Dry Wet /Slippery Linear Features Dry Wet /Slippery Linear Features
Philippines Even Even
(tropical forest land)
Korea E E
(eastern coastal plain)
Kuwait
(level rocky soil)
(sand)
Germany E E
(vegetated coastal highlands)
US Army Corps
of Engineers Engineer Research & Development Center

18. On-Road Performance Summary
Wheel Track
Paved/Secondary Trails Paved/Secondary Trails
Philippines
Korea
Kuwait
Germany
US Army Corps
of Engineers Engineer Research & Development Center

19. Tactical/Battlefield - Terrain Accessibility
2.5% NoGo
97.5 % terrain accessibility doesn’t mean much if the 2.5%
NoGo is between where you are and where you want to be!
US Army Corps
of Engineers Engineer Research & Development Center

20. Tactical and Operational Difference Between 4
and 11% NRMM No Go (West Germany Dry)
MTVL (4%)
14.6 Kilometers
21 Minutes
LAV III (11%)
14.9 Kilometers
23 Minutes
Surface Condition
Low Average Monthly (Mar)
Rainfall and surface is dry (i.e. It has
not rained within the past six hours).
Tactics
Cross Country and Trails.
Minimal Tactical or Operational Difference in Dry Cross Country
US Army Corps
of Engineers Engineer Research & Development Center

21. Tactical and Operational Difference Between 6
and 23% NRMM No Go (West Germany Wet)
MTVL (6%)
15.2 Kilometers
28 Minutes
LAV III (23%)
30.4 Kilometers
42 Minutes
Surface Condition
High Average Monthly (Mar) Rainfall and surface
is slippery (i.e. it has rained within the past 6
hours)
Tactics
Cross Country, Trails, and Paved Roads. Paved
Roads required since LAV III was Unable to
complete the mission using only trails and cross
country. The LAV III could not get to 4A and 6A.
Significant Tactical and Operational Impact on Wet Terrain.
US Army Corps
of Engineers Engineer Research & Development Center

22. Tactical and Operational Difference Between
MTVL and LAVIII Iran/Iraq Dry
MTVL
37.7Kilometers
4:41 Hours
LAV III
45.8Kilometers
3:38 Hours
Surface Condition
Low Average Monthly (Jan) Rainfall and
surface is dry (i.e. it has not rained within
the past 6 hours)
Tactics
Cross Country, Trails
Minor Tactical and Operational Impact.
US Army Corps
of Engineers Engineer Research & Development Center

23. Tactical and Operational Difference Between
MTVL and LAVIII Iran/Iraq Wet
MTVL
51.0Kilometers
7:45 Hours
LAV III
43.7Kilometers
Route included NOGO,
Mission was not completed
Surface Condition
High Average Monthly (Jan) Rainfall and
surface is Slippery (i.e. it has rained within
the past 6 hours)
Tactics
Cross Country, Trails, Roads
Significant Tactical and Operational Impact
US Army Corps
of Engineers Engineer Research & Development Center