FLMA - Unstable Slope Management Program Field Rating Form Rev 1.09 (December 2017)

Prepared by: Landslide Technology, WFLHD, USDA FS, BLM, BIA and NPS

SLOPE RATING FORM – SITE INFORMATION

Management Area: Date:

Hazard Type (select all 

that apply within one 

of the categories):

Rockfall Planar | Wedge | Toppling |

Raveling/Undermining | Rock Avalanche |

Indeterminate Rock Failures | Differential Erosion

Landslide Above, Below, or Across Route

Translational | Rotational | Debris Flow |

Shallow Slump | Erosional Failure

Road/Trail No.: ⃝ Trail Road/Trail Class: Rater: ⃝ Road 

Beginning Mile Marker: Ending Marker: Side: Weather:

Begin 

Coord.:

Lat. (xx.xxxxx): End 

Coord.:

Lat. (xx.xxxxx): Datum: AADT: Long. (-xxx.xxxxx): Long. (-xxx.xxxxx):

Length of Affected Road/Trail (ft): Slope Height (rock) /Axial Length (slide) (ft): Slope Angle (°):

Sight Distance (ft): Usable Roadway/Trail Width (ft): Speed Limit (mph):

Ditch Width (ft): RANGE ROCKFALLDitch Depth (ft): RANGE ROCKFALLDitch Slope (H:V): RANGE ROCKFALLBlk Size (ft)/Volume (cy): ROCKFALL

Annual Rainfall (in): RANGE Sole Access Route □ Yes □ No Fixes Present □ Yes □ No Photo # Range:

Comments:

PRELIMINARY RATING

Category Rating 3 9 27 81 Score

A. Landslide – Roadway Width 

Affected 0-5 Percent 6-25 Percent 26-50 Percent 51-100 Percent

B. Landslide – Slide/Erosion Effects

Visible crack or 

slight deposit of 

material /

minor erosion

1 inch offset, or 6-

inch deposit of 

material / major 

erosion will affect 

travel in < 5 yrs

2-inch offset or 

12-inch deposit/ 

mod. erosion 

impacting travel 

annually

4-inch offset or 24-

inch deposit/ severe 

erosion impacting 

travel consistently

C. Landslide – Roadway Length 

Affected 25 ft 100 ft 225 ft 400 ft CALC

D. Rockfall – Ditch Effectiveness 

(consider launch features) Good Moderate Limited No Catchment

E. Rockfall – Rockfall History Few Falls Occasional Falls Many Falls Constant Falls

F. Rockfall – Block Size or Volume 

per Event

1 ft

or

3 yd3 

2 ft

or

6 yd3 

3 ft

or

9 yd3 

4 ft

or

12 yd3 

CALC

G. All – Impact on Use

Full use continues 

with minor delay

Partial use remains

Use modification 

required, short (3 

mi/30 min.) detour 

available 

Use is blocked –

long (>30 min) 

detour available 

or less than 1 day 

closure

Use is blocked – no 

detour available or 

closure longer than 1 

week

H. All – AADT / Usage / Economic 

or Recreational Importance 

(highest rating applies)

50

Rarely Used 

Insignificant 

economic / rec. 

importance

200

Occasionally used 

Minor economic / 

rec. importance

450

Frequently used 

Moderate 

economic / rec. 

importance

800

Constantly used 

Significant economic 

/ rec. importance

CALC 

FOR 

AADT 

ONLY

LANDSLIDES TOTAL (A+B+C+G+H) CALC

ROCKFALL TOTAL (D+E+F+G+H) CALC

Preliminary Rating Good (15-21 pts) | Fair (22-161 pts) | Poor (>161 pts)

Sites rated as Fair or Poor receive detailed evaluation (complete back page)

ITALICIZED DATA CATEGORIES REQUIRED FOR FULL RATING
FLMA - Unstable Slope Management Program Field Rating Form Rev 1.09 (December 2017)

Prepared by: Landslide Technology, WFLHD, USDA FS, BLM, BIA and NPS

SLOPE RATING FORM – DETAILED SLOPE HAZARD RATING

Category Rating 3 9 27 81 Score

I. All – Slope Drainage

Slope appears dry 

or well drained; 

surface runoff well 

controlled

Intermittent water 

on slope; mod. well 

drained; or surface 

runoff moderately 

controlled

Water usually on 

slope; poorly 

drained; or 

surface runoff 

poorly controlled

Water always on 

slope; very poorly 

drained; or surface 

water runoff control 

not present

J. All – Annual Rainfall 0-10” 10-30” 30-60” 60”+

K. All – Slope Height (rockfall) / 

Axial length of slide (landslide) 25 ft 50 ft 75 ft 100 ft CALC Select One Unstable Slope Type Landslides/ Erosion (add A, B, C)

L. Thaw Stability (cold 

climates)

Unfrozen/Thaw 

Stable

Slightly Thaw 

Unstable

Moderately Thaw 

Unstable

Highly Thaw 

Unstable

M. Instability-Related 

Maint. Frequency Every 10 years Every 5 years Every 2 years Every year

N. Movement History Minor movement 

or sporadic creep 

Up to 1 inch 

annually or steady 

annual creep 

Up to 3 inches per 

event, one event 

per year

>3” per event, >6” 

annually, more than 

1 event per year 

(includes all debris 

flows)

Rockfalls

(add D, E, F)

O. Rockfall-Related 

Maint. Frequency

Normal, scheduled 

maintenance

Patrols after every 

storm event

Routine seasonal 

patrols Year-round patrols

Geologic Character

Case 1

P. Structural 

Condition Favorable Random Adverse 

Discontinuous

Adverse 

Continuous

Q. Rock 

Friction

Rough/

Irregular Undulating Planar Clay infilled/ Slickensided

Case 2

R. Structural 

Condition

Few differential 

erosion features

Occasional 

differential erosion 

features

Many differential 

erosion features

Major differential 

erosion features

S. Diff. in 

Erosion Rates Small difference Moderate 

difference Large difference Extreme difference 

T. LANDSLIDE HAZARD TOTAL (A+B+C+I+J+K+L+M+N) CALC

U. ROCKFALL HAZARD TOTAL (D+E+F+I+J+K+O+(greatest of P+Q or R+S)) CALC

DETAILED RISK RATING

V. Route Width or 

Trail Width

36 ft

14 ft

28 ft

10 ft

20 ft

6 ft

12 ft

2 ft CALC

W. Human Exposure Factor 12.5% of the time 25% of the time 37.5% of the time 50% of the time CALC if 

AADT avail

X. % of Decision Sight Distance 

(Judge avoidance ability on trails)

Adequate, 100% of 

low design value

Moderate, 80% of 

low design value

Limited, 60% of 

low design value

Very Limited, 40% of 

low design value

CALC for 

roads

Y. Right of Way (R/W) Impacts (If 

Left Unattended)

No R/W 

implications

Minor effects 

beyond R/W

Private property, 

no structures 

affected

Structures, roads, RR, 

utilities, or Parks 

affected

Z. Environmental/Cultural Impacts 

if Left Unattended

None/No potential 

to cause effects

Likely to effect/No 

hist. prop. affected

Likely to adversely 

affect/Finding of 

no adverse effect

Current adverse 

effects/Adverse 

effect

AA. Maintenance Complexity Routine effort/InHouse

In-House Maint./

Special project

Specialized 

equip./contract

Complex/Dangerous 

effort/location/

contract

BB. Event Cost $0-2k $2-25k $25-100k >$100k

CC. RISK TOTALS: (G+H+V+W+X+Y+Z+AA+BB) CALC

TOTAL USMP SCORE: LANDSLIDES (T+CC) OR ROCKFALL (U+CC) CALC

Total USMP Score Good (< 200 pts) | Fair (200 - 400 pts) | Poor (> 400 pts)
FLMA - Unstable Slope Management Program Field Rating Form Rev 1.09 (December 2017)

Prepared by: Landslide Technology, WFLHD, USDA FS, BLM, BIA and NPS

For the directly measurable categories, use the following formulas to calculate the exponent value (x) for the 

scoring formula y = 3x

. This will allow the calculation of a precise score for the category measurement and 

development of category scoring tables.

C. Length of roadway affected exponent:

= � h aa

25

F. Block size or the volume exponent formula:

bb = bb

vv = �

3

3 �

H. AADT exponent formula:

= �AAAAAAAA

50

K. Slope height/axial slide length exponent formula:

= ss h h

25

V. Width exponent formula:

= 44 − RR h ( )

8 for vehicles, = 18 − h ( )

4 for trail traffic

W. Human exposure factor exponent formula for roads and trails: 

=

�

AAAA

24 × ss h ( ) ×100

ss ss �

12.5

X. Percent decision sight exponent formula:

=

120 − � h

AAAA AAAAAA h ×100�

20