Recommended Objective Test 

Procedures for Road Departure

Crash Warning Systems

Sandor Szabo

Richard Norcross

U.S DEPARTMENT OF COMMERCE

Technology Administration

National Institute of Standards and Technology

Intelligent Systems Division

Gaithersburg, MD 20899-8230

NISTIR 7288
NISTIR 7288

Recommended Objective Test 

Procedures for Road Departure

Crash Warning Systems

Sandor Szabo

Richard Norcross

U.S DEPARTMENT OF COMMERCE

Technology Administration

National Institute of Standards and Technology

Intelligent Systems Division

Gaithersburg, MD 20899-8230 

February 2006

U.S. DEPARTMENT OF COMMERCE

Carlos M. Gutierrez, Secretary

NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY

William Jeffrey, Director
Recommended Objective Test Procedures for 

Road Departure Crash Warning Systems

February 3, 2006 

Prepared By: 

Sandor Szabo and Richard Norcross 

National Institute of Standards and Technology 

100 Bureau Drive, Mail Stop 8230 

Gaithersburg, MD 20899-8230 

This document was prepared for the U.S. Department of Transportation under interagency agreement 

DTFH61-00-Y-30132. Send comments and/or questions to sandor.szabo@nist.gov. 

Certain commercial entities, equipment, or materials may be identified in this document in order to describe 

an experimental procedure or concept adequately. Such identification is not intended to imply 

recommendation or endorsement by the National Institute of Standards and Technology, nor is it intended 

to imply that the entities, materials, or equipment are necessarily the best available for the purpose. 
This page is blank and may be removed for single-sided print out. 
History

June 26, 2002 – First draft of procedures for lateral drift warning system submitted to 

NHTSA. 

September 13, 2002 – Updated previous draft based on information obtained from the 

contractor's second quarterly review (July 24, 2002). Procedures added for curve speed 

warning system. 

December 18, 2002 – Updated based upon comments from Dave Smith and Lloyd Emery 

of NHSTA during meetings on December 10, 12 and 18, 2002. 

January 31, 2003 – This draft represents latest detailed design of tests at time of February 

5 FOT Quarterly Review. 

February 18, 2003 – This draft represents latest detailed design at time of trip to visit 

RDCWS contractor on February 18. The version includes curve speed warning test and 

the on-road nuisance tests. 

November 15, 2005 – This draft represents results from validation tests conducted by the 

RDCWS contractors and NIST. The on-road tests now exist separately in a Volpe/NIST 

document. This draft submitted to NHTSA as part of NIST’s RDCWS final report 
This page is blank and may be removed for single-sided print out. 
i 

Table of Contents 

1 Introduction................................................................................................................ 1

2 Definitions................................................................................................................... 4

2.1 Road Definitions ................................................................................................. 4 

2.2 Vehicle Definitions ............................................................................................. 9 

2.3 Warning System Definitions............................................................................. 13 

2.4 Environmental Definitions................................................................................ 16 

3 Basic Test Organization .......................................................................................... 18

4 Independent Measurement System........................................................................ 20

5 Warning System Evaluations.................................................................................. 23

5.1 Lateral Drift Evaluation .................................................................................... 23 

5.2 Curve Speed Evaluation.................................................................................... 27 

5.3 Timeliness of Warning...................................................................................... 28 

5.4 Efficacy Rate..................................................................................................... 29 

5.5 False Alarm Rate............................................................................................... 29 

6 Tests for Departure on Roads with Default Minimum AMR.............................. 30

6.1 One-Way Straight Road (Default Minimum AMR) ......................................... 31 

6.2 Two-Way Straight Road (Default minimum AMR)......................................... 38 

6.3 Curved Road (Default minimum AMR)........................................................... 43 

7 Tests for Departures on Roads with Maximum AMR ......................................... 49

7.1 Straight Road with Shoulder (Maximum AMR) .............................................. 50 

7.2 Curved Road with Shoulder (Maximum AMR) ............................................... 56 

8 Tests for Departures Toward an Obstacle ............................................................ 62

8.1 Barrier on Straight Road ................................................................................... 63 

8.2 Barrier on Curved Road.................................................................................... 70 

8.3 Obstacle on Shoulder on Straight Road............................................................ 76 

8.4 Obstacle on Shoulder on Curved Road............................................................. 83 

9 Tests for Departures on Curves at Excessive Speed............................................. 89

9.1 Excessive Speed on Curved Road..................................................................... 90 

9.2 Curve-Branch Detection ................................................................................... 95 

References........................................................................................................................ 99

Appendix A Methods for Determining Road Dimensions and Geometry............... 101

Appendix B Methods for Determining Lane Marker Characteristics..................... 102
1 

1 Introduction

Under the auspices of the Department of Transportation Intelligent Vehicle Initiative, the 

National Highway Traffic and Safety Administration (NHTSA) is evaluating the safety 

benefits of Road Departure Crash Warning Systems (RDCWS). These systems warn 

inattentive drivers when their vehicle is about to depart the road or collide with a roadside 

obstacle. To further understand the capabilities and benefits of these warning systems, 

the NTHSA, with the assistance of the National Institute of Standards and Technology 

(NIST), is devising test procedures that provide performance data in an objective and 

quantitative manner. These tests will evolve to reflect new insight into performance 

measurement and to maintain pace with the capabilities of the warning systems. In the 

long term, these tests may one-day become part of a standard procedure developers 

follow to achieve a safety rating similar to the “5-star” ratings used in the automotive 

industry today. 

The RDCWS Field Operation Test (FOT) program [1] validated many of the tests 

included in this report. The developers of the FOT RDCWS used an early version of 

these procedures to validate system performance. The developers adapted the procedures 

to meet the time, funding and available track geometry of the FOT. The RDCWS FOT 

contractor and NIST conducted the tests (called validation tests) at the Transportation 

Research Center (Maryville Ohio) from October 1, 2003 through April 28, 2004. The 

successful performance of the system during the tests allowed the FOT to proceed to 

Phase 2. 

These tests utilize considerable research from the international community, NHTSA, the 

Volpe National Transportation Systems Center, and NIST. 

1. An outline of the NIST RDCWS research results appears in a final report titled 

“Run-Off-Road Collision Avoidance Using IVHS Countermeasures” [2] (referred to 

as the ROR report in this document) 

2. The Road Departure Crash Warning System FOT Request for Applicants issued by 

the NHTSA [1] contains the performance capabilities expected of a warning system 

3. A NHTSA and Volpe National Transportation Systems Center report on an analysis 

of crash data identifies high-risk crash scenarios [3]. 

4. Reference [4] is the International Standards Organization test procedure for lane 

departure warning systems. 

A RDCWS consists of the sensor, the alert logic (correctness and timing) and the driver 

interface. The tests in this document address sensor and alert logic performance only. A 

complete evaluation of the driver interface would consider how a driver responds to the 

warning. These tests only evaluate the driver interface from the standpoint of whether 

the interface presented the warning or not. 
2 

The methods for evaluation of the warning system focus on two areas: correctness and 

timing. The correctness of each warning issued by the system is either true positive, false 

positive, false negative or true negative (Table 1). Statistical evaluations, such as efficacy 

rate (the percentage of warnings that produce the desired effects) and false alarm rate, 

summarize the results of the ratings. 

System Response Situations Requiring a 

Warning 

Situations in Which a 

Warning is not Required 

Warning True Positive (TP) 

Correctly warns of road 

departure 

False Positive (FP) 

False alarm 

No Warning False Negative (FN) 

Misses road departure 

True Negative (TN) 

Correctly does not warn of 

road departure. 

Table 1 Rating of warning system signals. 

The second area of evaluation examines the timing. A warning is of little benefit if it 

does not provide the driver with sufficient time to avoid the departure. Equations of 

motion are the basis of the performance metrics and determine the time afforded to a 

driver. Time limits determine whether a warning is useful. 

The methods quantify performance but do not specify the passing grade (e.g., the system 

must pass 90% of the tests). The organization interested in the test results should select 

the pass/fail criteria (some examples are provided in section 5). 

Evaluation of the metrics requires real-time measurements, preferably from an 

independent measurement system (IMS). Using the warning system sensors and 

processing algorithms may bias the system evaluation. For illustrative purposes, the test 

procedures include instructions for taking measurements using an IMS developed by 

NIST. 

The ability to detect the road edge is critical to the success of a warning system. For 

basic warning systems, the road edges are the lane markers in the vehicle’s current travel 

lane and the system issues a warning before the vehicle enters the adjacent lane. 

However, driver behavior can produce slight lane excursions and warnings for these 

instances might become a nuisance. The intent of a road departure crash warning system 

is to detect true crash conditions, such as driving off-road or drifting into obstacles 

outside the current lane. The objective to limit nuisance alarms and to focus on real 

crashes led to the concept of an available maneuver room (AMR), which is the region 

outside the lane marker that is drivable (e.g., paved shoulder) and clear of obstacles. The 

AMR added to the outer lane boundary defines the road boundary. 

Tests evaluate warning system performance for different types of road-edges. The first 

set of tests examines the system’s ability to detect a road edge defined by the outer lane 
3 

marker under the assumption that there is a minimal amount of AMR. These tests are 

appropriate for a basic lane departure system. 

The next test set examines the system’s ability to detect a road edge defined by the 

transition from pavement to off-road. The size of the shoulder may vary considerably, 

which would lead to a wide range of warning locations. Previous work [2] suggests a 

need for consistent warning location. Therefore, the AMR has a default maximum value 

regardless of the shoulder width. 

Another test set examines the system’s ability to detect a road edge defined by an 

obstacle on the shoulder. In one case, the vehicle drifts into an obstacle adjacent to the 

vehicle, such as a Jersey barrier or guardrail. In the other case, the vehicle drifts into an 

obstacle up ahead, such as a car parked on the shoulder. In either case, the road edge is 

an imaginary line at the base of the obstacle and parallel to the lane marker. 

The tests above address lateral drift scenarios. The final set of tests evaluates system 

performance when the vehicle is traveling too fast for an approaching curve, called the 

curve-speed scenario. 

This document has nine sections. The first section is this introduction. Section 2 contains 

definitions of the terminology used throughout the document. Section 3 contains an 

overview of the general test structure common to each test. Section 4 describes a 

measurement system to independently collect data for analyzing warning system 

performance. Section 5 describes evaluation procedures that are commonly used in lateral 

drift and curve speed tests. Section 6 contains tests to evaluate departures on roads with 

no available maneuver room. Section 7 contains tests to evaluate departures on roads with 

available maneuver room. Section 8 contains tests to evaluate departures towards barriers 

and obstacles. Section 9 contains tests to evaluate on curves due to excessive speed. 
4 

2 Definitions

This section contains definitions of terms used in the tests. The definitions fall into one 

of the following categories: road, vehicle, crash and environmental. 

2.1 Road Definitions 

2.1.1 Road 

The road consists of all travel lanes in the same direction of travel. This includes paved 

shoulders clear of obstacles. Roads may be divided or undivided. 

2.1.2 Undivided Road 

An undivided road is a road with two-way traffic (see Figure 1). Either double lane 

markers or a single dashed lane marker separates the directions of travel. A single dashed 

lane marker indicates passing in either direction. Double lane markers consist of 

combinations of solid and dashed stripes. Dashed indicates passing is permitted and solid 

prohibits passing. 

road boundaries

road

s

AMR

off

road

road 

boundaries

Obstacle

Figure 1. Undivided road includes all travel lanes and the shoulder (s) 

2.1.3 Divided Road 

A divided road is a road with one-way traffic (see Figure 2). Dashed white lane markers 

separate lanes of traffic. 
5 

road boundaries

road

s

AMR AMR

s

off

road

barrier

road boundaries

Obstacle

Figure 2. Divided road includes all travel lanes and the shoulder (s) 

2.1.4 Lane 

The lane is the area of paved surface between two parallel lane markings. The distance 

between the inside edges of the lane markings should be 3.7 m (12 ft). The lane must 

have markings on the left side. If the lane has no markings on the right side (worn or 

missing), then the lane is 3.7 m measured from the inside edge of the left side lane 

marker. 

2.1.5 Shoulder 

The shoulder is the portion of drivable surface to the right of an undivided road and on 

either side of a divided road. Refer to s in Figure 1 and Figure 2. 

2.1.6 Available Maneuver Room 

The available maneuver room is the region of the road outside the outer lane marker that 

is safe to drive (see AMR in Figure 1 and Figure 2). Obstacles on the shoulder or 

absences of shoulders limit the AMR. By design, the AMR does not exceed a default 

maximum value (1 m), regardless of the size of the shoulder. The default minimum 

value is 15 cm (6 in). 

2.1.7 Road Boundary 

The road boundary (also referred to as road edge) is the real or imaginary boundary line 

on the pavement and defines the edge of the road (see Figure 1 and Figure 2). The road 

boundary is parallel to the outer lane marker and extends beyond the outer lane marker by 

the available maneuver room distance. A warning system senses the available maneuver 
6 

room (e.g., obstacles on the shoulder) and adjusts the road boundary accordingly. The 

warning system also uses the distance to the road boundary to calculate when to issue a 

warning. 

2.1.8 Curved Road 

A curved road is a section of road with a radius less than 1000 m. 

2.1.9 Straight Road 

A straight road is a section of road with a radius greater than 1000 m. 

2.1.10 Lane Markings 

The definitions for lane markings come from part three of the Manual on Uniform Traffic 

Control Devices (http://mutcd.fhwa.dot.gov/). Lane marker dimensions for the test are: 

Lane marker value Dimensions 

Maker width 10 cm to 15 cm (4 in to 6 in) 

Dashed marker length 3 m (10 ft) ± 5 % 

Dash marker gap length (distance between dashed 

markers) 

9 m (30 ft) ± 5 % 

Appendix A “Methods for Determining Road Dimensions and Geometry” contains the 

recommended method to verify the lane marker dimensions. 

The manual states: 

Centerline pavement markings, when used, shall be the pavement markings used to 

delineate the separation of traffic lanes that have opposite directions of travel on a 

roadway and shall be yellow.

The centerline markings on two-lane, two-way roadways shall be one of the 

following as shown in Figure 3B-1: 

A. Two-direction passing zone markings consisting of a normal broken yellow line 

where crossing the centerline markings for passing with care is permitted for traffic 

traveling in either direction; 

B. One-direction no-passing zone markings consisting of a normal broken yellow 

line and a normal solid yellow line where crossing the centerline markings for 

passing with care is permitted for the traffic traveling adjacent to the broken line, 

but is prohibited for traffic traveling adjacent to the solid line; and 

C. Two-direction no-passing zone markings consisting of two normal solid yellow 

lines where crossing the centerline markings for passing is prohibited for traffic 

traveling in either direction. 
7 

When used, lane line pavement markings delineating the separation of traffic lanes 

that have the same direction of travel shall be white. 

Where crossing the lane line markings with care is permitted, the lane line markings 

shall consist of a normal broken white line. 

Where crossing the lane line markings is discouraged, the lane line markings shall 

consist of a normal solid white line. 

Where crossing the lane line markings is prohibited, the lane line markings shall 

consist of two normal solid white lines. 

If used, the right edge line pavement markings shall consist of a normal solid white 

line to delineate the right edge of the roadway.
8 

2.1.11 Lane Marker Reflectivity 

The lane marker reflectivity (or brightness) is the ratio between the luminance of the 

marker (light coming from the marker) and the illuminance on the marker (the light 

reaching the marker). 

In daylight conditions, the measure of reflectivity is the coefficient of luminance under 

diffuse illumination (Qd). 

In nighttime conditions, the brightness is a function of the headlights and the 

retroreflectivity of the lane marker. The measure of retroreflectivity is the coefficient of 

retroreflected luminance (RL). 

Both of these coefficients are in units of millicandelas per square meter per lux (mcd•m2

•lx-1). The geometry regarding the orientation of the light source, the orientation the 

viewer and the distance to the lane marker is part of the measurement process [9]. 

The values below come from Table 1 in reference [14]. 

Lane Marker 

Color 

Minimum coefficient under diffuse 

illumination, Qd (mcd m-2/lx) 

White < 130 (for Asphalt) 

 < 160 (for Concrete) 

Yellow < 100 

 

Appendix B contains the recommended method to verify the lane marker reflectivity. 

2.1.12 Lane Marker Color 

The daytime color of the lane marker is defined by its chromaticity and luminance 

(x,y,Y). The CIE (Commission International d'Eclairage, or International Commission 

on Illumination, http://www.cie.co.at/cie/) chromaticity chart shows the coordinates (x,y) 

of visible colors. The luminance (Y) defines the brightness of the color. 

The four points listed in the table below bound the region of allowable colors for both 

white and yellow lane markers. Each color includes the luminance factor (Y). The 

values come from Table 1 and Table 3 of reference [12] . 

Lane Marker 

Color 

Daytime Chromaticity 

Coordinates (x,y) 

Luminance factor Y (%) 

White 0.355, 0.355 

0.305, 0.305 

0.285, 0.325, 

0.335, 0.375 

Minimum of 45 

Yellow 0.560, 0.440 

0.490, 0.510 

0.420, 0.440, 

0.460, 0.400 

Minimum of 30 
9 

A commercial measurement device should to measure color properties. 

Figure 3. CIE Chromaticity Chart 

2.2 Vehicle Definitions 

Several definitions follow the terminology in reference [6]. 

2.2.1 Vehicle Coordinate Systems 

Figure 4 shows the vehicle coordinate system. The origin of this system lies on the road 

directly under the vehicle's center of gravity. The z-axis points down into the road. 
10 

FRONT

X

Y

Z

Figure 4. Vehicle coordinate system (z-axis is down) 

2.2.2 Longitudinal Speed 

The longitudinal speed is the vehicle's speed along the x-axis. The ROR report 

recommends that the warning system should determine vehicle velocity to an accuracy of 

3 miles per hour (mph) (L-20 page 24 in [2]). Use the time to travel a known distance to 

verify the speedometer’s accuracy. 

The vehicle’s speedometer provides vehicle speed during tests. An independent 

measurement system (IMS) verifies the vehicle’s speed during a test using a dash camera 

aimed at the speedometer. 

2.2.3 Lateral Position 

The lateral position is the position of the vehicle's origin relative to the center of the lane. 

The lateral position measurement is along the vehicle y-axis. Most measurements in this 

test use a similar lateral measurement called Distance to Road Edge (see section 2.2.7). 

2.2.4 Lateral Velocity 

The lateral velocity is the rate of change of lateral position. 

2.2.5 Yaw Rate 

Yaw rate is the rate of rotation about the vehicle z-axis.

2.2.6 Road Departure 

The vehicle departs the road when the outside edge of any of the vehicle tires crosses the 

outside edge of the road. 

2.2.7 Distance to Road Edge 

The distance to the road edge is the distance from the vehicle's outside front tire to the 

road edge measured along the vehicle’s y-axis. 
11 

y

Road

Edge

Figure 5. Distance to road edge is perpendicular to vehicle 

 

The tests measure the lateral position using the IMS (see section 4) video. A calibration 

procedure transforms pixels in the image into distance to road-edge measurements. The 

analyst selects the pixel on the road edge and the IMS returns the distance. 

2.2.8 Road Departure Rate 

The road departure rate is the rate of change in distance to the road edge. 

y0

y1

Road

Edge

Figure 6. Computing lateral velocity 

Use the following equation to compute road departure rate: 

1 0

1 0

t t

y y vlat −− = Road Departure Rate 

Where: 

y1, y0 - are the lateral positions at time t1 and t0 respectively (see figure above). 

Many tests require the driver to depart the road at a given rate, for example, above 0.75 

m/s. The driver achieves the desired departure rate by traversing a known distance in a 

known time interval. For example, the driver starts the departure at 0.75 m from the lane 

marker and crosses the lane marker in one second. Afterward, the analyst uses the IMS 

calibrated video to measure the exact departure rate. 
12 

2.2.9 Road Departure Angle 

The road departure angle is the angle between the forward x-axis of the vehicle and the 

road edge. 

θ

v

vlat

Road

Edge

Figure 7. Departure angle on straight road. V is the forward velocity and Vlat is the lateral velocity. 

The following formula estimates the departure angle from the departure rate and the 

forward velocity: 

⎟

⎠

⎞ ⎜

⎝

⎛

⎟

⎠

⎞ ⎜

⎝

⎛ =° −

π

θ 180

tan 1

v

vlat Departure Angle (in degrees) from forward and 

lateral velocities. 

Where: 

vlat = is the road departure rate (m/s) (see section 2.2.8) 

v = vehicle forward speed (m/s) 

2.2.10 Distance to Curve Entry Point 

The curve entry point marks the transition between a straight road segment and a curved 

road segment (see Figure 8). The distance to the curve entry point is measured using the 

IMS in the following manner: 

Determine the start location of the measurement, for example, the time of a warning. 

Note the lateral distance to the departure-side road edge. Record the initial (n2, e2) 

location of the vehicle. 

Advance the video until the lateral distance visibly decreases. This marks the curve entry 

point. Record the location of the vehicle at the curve entry point (n2, e2). 

Determine the distance to the curve entry point using the following formula: 

( )( )2

1 2

2

1 2 x n n e e m = − + − Measured distance to Curve Entry Point 
13 

Figure 8. Measured distance to curve entry point at time of warning (xm) 

2.3 Warning System Definitions 

2.3.1 System Response Rating 

The rating of a system’s response to a warning situation falls into one of the following 

categories [6]: 

System Response Situations Requiring a 

Warning 

Situations in Which a 

Warning is not Required 

Warning True Positive (TP) 

Correctly warns of road 

departure 

False Positive (FP) 

False alarm 

No Warning False Negative (FN) 

Misses road departure 

True Negative (TN) 

Correctly does not warn of 

road departure. 

Table 2 Rating of warning system signals. 
14 

2.3.2 Imminent Crash Condition 

An imminent crash condition exists when there is a high probability of a lateral collision, 

a loss of steering control or a rollover. A RDCWS considers leaving the paved portion of 

the road at a high speed as an imminent crash condition because of the high probability of 

loss of steering control and rollover. 

2.3.3 Crash Warning 

A crash warning is a signal to the driver indicating an imminent crash condition exists 

and that the driver should take immediate action to prevent the crash. 

2.3.4 Advisory Warning 

An advisory warning is a signal to the driver that the vehicle is about to drift outside the 

current lane or that the current speed is too great for an upcoming curve. 

2.3.5 Warning Sensitivity 

Warning sensitivity is a user-controlled variable that determines the timing of a warning. 

High sensitivity produces earlier warnings and low sensitivities produce later warnings. 

The sensitivities affect evaluation of a warning system by setting a maximum value for 

lateral acceleration (due to driver steering correction) on a lateral drift departure and 

required longitudinal deceleration (due to driver braking to slow the vehicle) on a curve 

over-speed departure. A summary of the warning system sensitivities appears in the 

following table [7]. Unless stated otherwise, the sensitivity is at the mid-range value (3). 

Sensitivity alat 

m/s2

dreq 

m/s2

1 4.12 (0.42 g) 6.86 (0.70 g) 

2 3.53 (0.36 g) 5.88 (0.60 g) 

3 2.94 (0.30 g) 4.90 (0.50 g) 

4 2.35 (0.24 g) 3.92 (0.40 g) 

5 1.76 (0.18 g) 2.94 (0.30 g) 

Table 3 Warning system sensitivity values for lateral 

acceleration (alat) and longitudinal deceleration (dreq), 

where g equals gravity (9.8 m/s2

). 

2.3.6 Reaction Time 

The reaction time defines the amount of delay between onset of a warning and onset of a 

steering maneuver by the driver. An average reaction time for these tests is tr = 1.5 s. A 

lower bound (tl) and an upper (th) define the range of acceptable reaction times. The 

evaluation equations use these values to determine the earliest and latest location of a 

warning. Table 4 gives suggested values for the reaction times. 
15 

Name Time Description 

tl 0.75 s Lower bound used to define latest possible 

warning location. 

tr 1.5 s Ideal reaction time 

th 2.0 s Upper bound used to define earliest 

possible warning location. 

Table 4. Reaction time with low and high limits. 

2.3.7 Obstacle 

An obstacle is an object of sufficient mass to cause damage to a vehicle upon collision. 

2.3.8 Radar Corner Cube Reflector 

Radar cross section (RCS) is the measure of a target's ability to reflect radar signals in the 

direction of the radar receiver. The corner reflector has an RCS almost as high as a flat 

plate but over a wider reflectance angle (over ±60o). 

H

Figure 9. Corner Cube Reflector 

Use the following equation to determine the height of a corner cube for a desired RCS. 

4

1 2

4

3

⎟

⎟

⎠

⎞

⎜

⎜

⎝

⎛ = π

λ σ H Height of corner cube 

Where: 

H = height of corner cube (m) 

σ = desired radar cross section (RCS) (m2) 

λ = radar wavelength (m) 

2.3.9 Time of Warning 

The time of warning is the time when the warning system issues an alert. Determining 

whether a warning is late, early or on time requires the time of the warning relative to the 

road departure. 

The IMS (see section 4) captures the time of the warning from the visual icon on the 

warning system display or from the audible alert (using a microphone). The analyst 

searches through the video to locate the warning and uses the GPS clock and the video 

frame clock (the frames are 29.9 ms apart) to measure the time of the warning. 
16 

2.3.10 Time to Line Crossing 

The time to line crossing is the calculated time until the vehicle's lead tire crosses an inpath lane marker given the vehicle continues on its current trajectory. 

2.3.11 Time to Road Departure 

The time to departure is the time until the vehicle's lead tire crosses a line parallel to the 

outer lane marker offset by the available maneuver room. 

2.3.12 Nuisance Alarm 

Nuisance alarms are warnings deemed unwarranted by a driver. They include false 

alarms due to incorrectly predicting the time or position of a crash (i.e., early warning) 

and false positives due to incorrect sensor readings (from noisy or cluttered 

environments). 

2.4 Environmental Definitions 

2.4.1 Daylight Time 

Daylight is the times of day starting at sunrise and ending at sunset. The times are 

available from the US Naval Observatory (http://aa.usno.navy.mil/data/). 

2.4.2 Night Time 

Night is the times of day after civil twilight at sunset and ending at twilight before 

sunrise. Civil twilight is when the sun is 6 degrees below the horizon. According to 

definitions used by the US Naval Observatory: 

In the morning before the beginning of civil twilight and in the evening after the end 

of civil twilight, artificial illumination is normally required to carry on ordinary 

outdoor activities. Complete darkness, however, ends sometime prior to the 

beginning of morning civil twilight and begins sometime after the end of evening 

civil twilight. 

The times of civil twilight are available from the US Naval Observatory 

(http://aa.usno.navy.mil/data/). 

2.4.3 Rain 

Rain is precipitation in the form of water drops larger than 0.5 mm (0.02 in). The 

following table shows how rainfall intensity is determined: 

Rainfall 

Intensity 

Rate-of-fall in 6 min Visual Estimation 

Light ≤ 0.25 mm 

(0.01 in) 

From scattered drops that, regardless of 

duration, do not completely wet an exposed 

surface up to a condition where individual 

drops are easily seen 

Moderate 0.25 mm to From scattered drops that, regardless of 
17 

0.762 mm (0.03 in) duration, do not completely wet an exposed 

surface up to a condition where individual 

drops are easily seen. 

Heavy > 0.762 mm Rain seemingly falls in sheets; individual drops 

are not identifiable; heavy spray to the height 

of several centimeters over hard surfaces. 

Table 5. Rain rate of fall. 

2.4.4 Fog 

Fog is as a visible aggregate of minute water particles (droplets), which is close to the 

Earth's surface and reduces horizontal visibility to less than 1 km (5/8 mi), and unlike 

drizzle, it does not fall to the ground. 

Names given to fog types identify their methods of formation. The principle types are 

radiational fog, ice fog, advection fog, upslope fog, rain-induced fog, and steam fog. 

These types of fog are called "dense" when the surface visibility is equal to or less than 

400 m (1/4 mi). A Dense Fog Advisory occurs when the dense fog becomes widespread. 

2.4.5 Snow 

Snow precipitation consists of water crystals, mostly branched in the form of six-pointed 

stars. It usually falls steadily for several hours or more. Qualifiers, such as occasional or 

intermittent, indicate a steady, prolonged (for several hours or more) fall is not expected. 

Like rain, visibility determines snow intensity. The following table shows snow intensity 

versus visibility: 

Snow Intensity Visibility 

Light > 1 km (5/8 mi) 

Moderate 400 m (1/4 mi) to 1 km 

Heavy < 400 m 
18 

3 Basic Test Organization

Each test procedure in this document consists of the following subsections. 

Test Title 

Each test in this document starts with a short description of the purpose of the test and a 

figure (see Figure 10) showing the trajectory of the vehicle, the road geometry, pertinent 

test props and key events of the test. 

 

1

2

3

s

Defined events

Vehicle trajectory

Scenario variables

Barrier

Figure 10. Each test procedure includes a figure that illustrates pertinent aspects of the test. 

Events and System Response 

This section describes the events during the test and the response of the warning system 

to the event. Typically, the response is a specific warning signal. 
19 

Conditions 

This section describes the conditions for the test. Some conditions remain fixed 

throughout the test, for example, road geometry and lane marker quality. Other 

conditions may vary between a set of tests, for example, speed and departure rate. 

Measurements 

This section lists all the measurements that are required for the tests. Also presented are 

methods and procedures for processing the measurements. 

Procedure 

This section lists the steps of the test, which have the following format: 

1. Setup and verify scenario conditions. 

2. Drive system/vehicle along desired trajectory 

3. Record trajectory and warning system responses 

4. Process data to determine performance variables 

5. Evaluate the system response to determine whether system passed 

Evaluation Methods 

This section contains the methods for judging whether the system passes the test. The 

methods used for most tests are: 

1. Is the correct warning system response given (e.g., did the system miss the event)? 

2. Is the timing of the warning acceptable? 
20 

4 Independent Measurement System

This section describes an independent measurement system used to collect warningsystem performance data required for system evaluation. Evaluation of the warning 

system should use sensors and equipment separate from the warning system under test. 

For example, the distance to a lane marker at the time of warning should not come from 

the warning system itself. Errors in the warning system camera and image-processing 

algorithm could lead to incorrect assessment of warning system performance. Details of 

the IMS appear in [5]. This section provides enough details to understand one approach 

for collecting data and measurements to analyze warning system performance. 

Quad 

Multiplexer

DV 

Recorder

DGPS Receiver/Modem

forward and side cameras

dash camera cab microphone

audio 

channel

audio 

channel

analog 

video

Figure 11. Independent Measurement System

Figure 11 illustrates the components of the IMS described [5]. Three cameras situated 

on a roof rack provide forward and side-looking video. A fourth camera mounted on the 

dash captures the warning system display. A quad multiplexer combines the four video 

signals into a single video stream. The output of the quad appears in Figure 12. 
21 

Figure 12. Four camera views combined into one. Top left and right are view of 

calibration sticks aligned with front wheels. Bottom right shows calibration 

sticks on the road in front of vehicle. Bottom left is view of warning system 

display. 

The cameras perform the following functions: 

1. The left and right downward facing cameras measure lateral distances relative to the 

front wheels. The top left and right quad in Figure 12 show calibration sticks for 

calibrating the side looking cameras. The black and white stripes on the calibration 

sticks have known dimensions. The user identifies the pixel locations of the stripes 

(see red circles in top left of Figure 13, which defines a transformation between pixel 

coordinates in the image and ground coordinates relative to the front wheels. After 

camera calibration, the sticks are no longer required. The overlaid red circles indicate 

the calibrated portion of the video data (see top right quad in Figure 13). Clicking on 

a pixel centered with the red circle returns the lateral distance as if the calibrated 

sticks existed. Linear interpolation gives distance measurements between the circles. 

2. A forward facing camera provides lateral measurements forward of the vehicle. The 

camera calibration uses calibration sticks as well. This view provides a better view of 

the surrounding environment then just the side looking cameras. 

3. A dash view camera shows vehicle speed and when an alert is given. 
22 

Figure 13. Result of pixel to ground calibration is shown using red circles. 

Circles in top left view identify transitions from black to white marking on 

calibration stick. After removal of the calibration stick (e.g., top right 

view), the circles provide a reference for the operator when measuring 

lateral distances from the front wheel. 

Other components of the IMS include a Differential Global Positioning Satellite (DGPS) 

receiver to sense vehicle position and velocity, and a cab microphone to pick up the 

audible alerts and comments from the driver. To simplify data collection, a modem-like 

device converts the GPS data into an audible signal. A digital videocassette recorder 

(DV VCR) simultaneously records the output of the video, microphone (one audio 

channel) and GPS (the second audio channel), ensuring synchronization of the data 

streams. 
23 

5 Warning System Evaluations

This section describes various methods for rating warning system performance that are 

common among tests. The methods describe how to score the system, but the methods 

do not specify what score is acceptable. Some example criteria for establishing an 

acceptable score include: 

1. The system must pass 95% of the runs for a given test (good when there is large 

number of test runs) 

2. The system may only fail 1 time for a given set of test runs (good when there is a 

small number of test runs) 

The organization interested in the test results should specify the acceptable pass/fail 

criterion. 

5.1 Lateral Drift Evaluation 

A warning must provide a driver with time to react and time to avoid (i.e., steer away 

from) a departure. The reaction phase starts at the time of warning and continues until 

the driver initiates the steering correction. The steer phase consists of the trajectory the 

vehicle follows during the steering correction. The magnitude of the steer should not 

exceed alat limits defined in Table 3 of section 2.3.5 (Warning Sensitivity). The lateral 

drift analysis uses separate equations for straight or curved roads. 

5.1.1 Straight Road 

A lateral drift on a straight road occurs when the vehicle departs a straight road at a fixed 

angle to the direction of the roadway. 

r(1-Cosθ)

θ

θ

vtrSinθ

r

yw

Road 

Edge

driver 

reaction phase

driver

steer phase

θ

Vehicle location

when alert issued

Figure 14. Geometry for a lateral drift scenario on a straight road 

Given the geometry of the lateral departure of a straight road shown in Figure 14, one 

determines the desired lateral distance to issue an alert using the following equation: 
24 

( )

θ

θ θ

cos

sin + 1− cos = vt r

y r

w , 

Where: 

v = vehicle forward speed (m/s) 

tr = delay between warning and start of steering (see section 2.3.6) (s). 

θ = the departure angle (radians). If measuring departure rate, convert to angle using 

equation in section 2.2.9). 

r = the radius of the curve the vehicle must travel to avoid the departure (m) 

The equation simplifies to: 

y = vt tanθ + r( ) 1 cosθ −1 w r . 

Use the measured lateral velocity (vlat) to calculate the departure angle (see section 2.2.9): 

⎟

⎠

⎞ ⎜

⎝

⎛ = −

v

v 1 lat θ tan

The radius should not cause the vehicle to exceed a maximum lateral acceleration (alat, 

see section 2.3.5), therefore: 

alat

v

r

2

=

To determine the desired location of a warning (the lateral distance to road boundary) for 

comparison with the measured time of a warning: 

1. Measure v and vlat at the time of warning. 

2. Obtain tr from section 2.3.6 and alat from section 2.3.5 sensitivity setting 3. 

3. Calculate desired location using the following equation: 

( ) 1 cos 1

2

= + θ −

lat

w lat r a

v

y v t (1) 

Use the following procedure to determine whether the actual measured warning location 

during a test is early, late or on time. 

1. Use the desired location warning equation to determine the latest warning location 

(LWL) (warning occurs closer to road boundary) using sensitivity setting 1 (highest 

alat from section 2.3.5) and reaction time tl (shortest reaction time from section 2.3.6). 

2. Use the desired location warning equation to determine the earliest warning location 

(EWL) (warning occurs farther from road boundary) using sensitivity setting 5 

(lowest alat from section 2.3.5) and reaction time th (longest reaction time from 

section 2.3.6). Use the following relationships to compare the measured location of 

the warning (ym) with LWL and EWL to determine whether the warning is early, late

or on time (refer to Figure 16): 

If ym > EWL, then the warning is early

If ym < LWL, then the warning is late

If EWL ≥ ym ≤ LWL, then the warning is on time
25 

Figure 15 Relationship to determine timeliness of warning on 

lateral-distance based warning. 

5.1.2 Curved Road 

A lateral drift on a curved road occurs when the vehicle is traveling straight and departs a 

curved road. 

Figure 16. Geometry for a lateral drift scenario on a curved road 

Reference [10] describes the derivation of the lateral acceleration required to avoid a 

lateral departure on a curved road (see Figure 16 - note the change in x and y axes to 

remain consistent with y measurements being lateral from the vehicle): 
26 

⎟

⎟

⎠

⎞

⎜

⎜

⎝

⎛

⎟

⎟

⎠

⎞

⎜

⎜

⎝

⎛

+

−

+ −

=

−

w r

w

w r

c

lat

x vt

r y

x vt r

v a

1

2

sin 2tan

(2) 

Where: 

v = vehicle forward speed (m/s) 

rc = the radius of the curve (m) 

tr = delay required by driver to initiate the steering correction 

yw = the lateral distance to the center of the curve (m). 

xw = the longitudinal distance to the curve entry point (m) (See section 2.2.10.) 

Subject to: 

r c w w vt < r − y − x 2 2 (3) 

(The onset of steering must occur prior to the road boundary). 

Note that in this scenario, the vehicle must travel straight during the departure (i.e., 

remain parallel to the road edge until entering the curve). The initial lateral position (yw)

dictates the ideal location for a warning (xw,), which is relative to the curve entry point. 

The curve entry point is the point where the lateral distance to the road edge starts to 

decrease. Using the IMS, the distance is derived from speed and time. 

To determine the desired location of a warning (longitudinal distance to curve entry) for 

comparison with the measured time of a warning: 

1. Measure v, the lateral distance to the road edge ym, and rc during a test. 

2. Determine yw from yw = rc – ym. 

3. Obtain tr from section 2.3.6 and alat from section 2.3.5 sensitivity setting 3. 

4. Calculate desired location using the following equation: 

( ) w r

lat

w c w c y vt

a

v

x r y r −⎟

⎟

⎠

⎞

⎜

⎜

⎝

⎛ = − − +

2 2

(4) 

Use the following procedure to determine whether the actual measured warning location 

during a test is early, late or on time. 

1. Measure v, the lateral distance to the road edge ym, the longitudinal distance to the 

curve entry xm (note: xm is negative if vehicle hasn’t entered the curve) and rc at the 

time of a warning. 

2. Determine yw and xw from yw = rc – ym and xw =xm. 

3. If r c w w vt ≥ r − y − x 2 2 then turn begins after vehicle leaves the lane (can’t use equation 

(2)). Classify warning as late. 

4. Use equation (2) to determine the lateral acceleration required to stay on the road. 

5. If alat > sensitivity setting 1 (highest alat from section 2.3.5) then classify warning as 

late. 

6. If alat < sensitivity setting 5 (lowest alat from section 2.3.5) then classify warning as 

early. 

Formatted: Lowered by 7 pt
27 

7. Else alat falls within the acceptable limits and classify the warning as on time. 

5.2 Curve Speed Evaluation 

A curve-speed warning must provide a driver with time to react (reaction phase) and to 

slow (brake phase) to a safe speed. The braking action should not exceed a limit on 

deceleration. 

Figure 17. Geometry for a curve speed warning scenario. 

Use the following equation to calculate the amount of deceleration required to reach the 

safe speed: 

( ) x t v

v v d

w r

s

req −

− = 2

2 2

(5) 

Where: 

dreq = required deceleration (m/s2

) 

v = vehicle initial forward speed (m/s) 

vs = safe speed for the curve (m/s) 

tr = driver reaction time (s) 

xw = the distance between the warning location and the start of the curve (m) (See 

section 2.2.10.) 

The safe speed for a curve of radius r does not exceed a maximum lateral acceleration 

(alat, see section 2.3.5). Use the following equation to calculate the safe speed: 

v a r s = lat (6) 

To determine the desired location of a warning (distance to curve entry) for comparison 

with the measured time of a warning: 

1. Measure v, ya, and rc during a test. 

2. Obtain tr from section 2.3.6, and alat and dreq from section 2.3.5 sensitivity setting 3. 

3. Calculate desired location using the following equation: 

t v

d

v v

x r

req

s

w + − = 2

2 2

(7) 

Use the following procedure to determine whether the actual measured warning location 

during a test is early, late or on time. 
28 

1. Use the desired location warning equation to determine the latest warning location 

(LWL) (warning occurs closer to road boundary) using sensitivity setting 1 (highest 

alat from section 2.3.5) and reaction time tl (shortest reaction time from section 2.3.6). 

2. Use the desired location warning equation to determine the earliest warning location 

(EWL) (warning occurs farther from road boundary) using sensitivity setting 5 

(lowest alat from section 2.3.5) and reaction time th (longest reaction time from 

section 2.3.6). 

3. Use the following relationships to compare the measured location of the warning (xm) 

with LWL and EWL to determine whether the warning is early, late or on time (refer 

to Figure 18): 

If xm > EWL, then the warning is early 

If xm < LWL, then the warning is late 

If EWL ≥ xm ≤ LWL, then the warning is on time 

Figure 18. Relationship to determine timeliness of warning on lateral-distance based warning. 

5.3 Timeliness of Warning 

Once warnings are evaluated as early, late or on time for the given scenario (departure on 

straight road, departure on curved road, curve speed departure), the results are 

accumulated as follows: 

100

#

# ⎟⋅

⎠

⎞ ⎜

⎝

⎛

TP

Early Percent of Warnings Early 

100

#

# ⎟⋅

⎠

⎞ ⎜

⎝

⎛

TP

OnTime

Percent of Warnings on Time 

100

#

# ⎟⋅

⎠

⎞ ⎜

⎝

⎛

TP

Late

Percent of Warnings Late 
29 

Where #Early, #OnTime, #Late, and #TP are the total number of early warnings, on time 

warnings, late warnings, and the true positive warnings. Each test procedure describes 

how to determine if a warning is a true positive (also referred to as the correct response 

(CR)). The results of several test runs are summarized in the following table. 

Test Run Summary Results 

Combined Results for 

all runs 

# of 

runs 

# 

CR 

# 

OT 

# 

E 

# 

L 

% 

OT

% 

E 

% 

L 

Date/time of test runs 

5.4 Efficacy Rate 

Reference [6] defines the efficacy rate as the rate that a desired effect occurs. 

100

# #

# ⎟⋅

⎠

⎞ ⎜

⎝

⎛

+ = TP FN

TP efficacy rate

5.5 False Alarm Rate 

Reference [6] defines the false alarm rate. 

100

# #

# ⎟⋅

⎠

⎞ ⎜

⎝

⎛

+ = TP FP

FP false alarm rate
30 

6 Tests for Departure on Roads with Default Minimum AMR

The tests in this section evaluate warning system response to road departures where the 

available maneuver room is at a default minimum. This situation arises when the sensor 

processing has unacceptable uncertainty, when maps of the road network are unavailable, 

or when the warning system lacks the sensing capability to detect the drivable surface on 

the side of the road. 

The tests evaluate the system’s ability to: 

1. Detect lane markers, 

2. Determine lane marker type, 

3. Determine departure velocities, 

4. Determine driver lane change intent 

The test scenarios include departures on a divided straight road, on an undivided straight 

road and on a divided curved road. 
31 

6.1 One-Way Straight Road (Default Minimum AMR) 

This test assesses the performance of the lateral drift warning function for road departures 

on divided straight roads. This scenario falls under the "going straight on freeway with 

two lanes at non-junction" scenario identified in the NHTSA test scenario report as one 

of the major settings for road departure crashes [3]. The test also examines warning 

system response during lane changes (i.e., when vehicle crosses dashed lane markers) 

with and without turn signals. 

The figure below illustrates the test scenario. Both a left and a right departure are tested. 

A B

1

2

1

2

AMR AMR

Road

Boundary

Figure 19. Scenario for road departure on divided road 

6.1.1 Events and System Response 

The following table defines the events for this test and the correct warning signal the 

system shall provide. See the figure above to locate the event (e.g., Id A1 is label 1 in 

figure A). 
32 

Id Event Correct Response 

A1 Crossed dashed line 1. Issue no warning if correct turn signal active. 

2. Issue an advisory warning if no turn signal active 

or incorrect turn signal active. 

A2 Road departure 1. Issue road departure warning 

B1 Same as A1 1. Same as A1 

B2 Same as A2 1. Same as A2 

6.1.2 Test Conditions 

The conditions for this test include the following. 

6.1.2.1 Road Geometry 

The road geometry for the test is the following: 

Road Geometry Dimension 

Straight (defined using radius of curvature) > 1000 m 

Appendix A, Methods for Determining Road Dimensions and Geometry, contains the 

recommended method to verify the road geometry. 

6.1.2.2 Available Maneuver Room 

In this test, the warning system recognizes the road edge but cannot determine if there is 

additional AMR. Therefore, the system should assume a default minimum AMR. 

Available Maneuver Room Comment 

15 cm (6 in) Default minimum AMR 

6.1.2.3 Speed 

The vehicle speeds during the tests cover warning system operating range. 

Low Speed Medium Speed High Speed 

64 km/h (40 mph) 89 km/h (55 mph) 113 km/h (70 mph) 

6.1.2.4 Departure Rate 

The vehicle departure rates are either high or low. These rates are comparable to the 

rates suggested in the ROR report and in the ISO standard for testing lateral drift warning 

systems. 

Low Departure Rate High Departure Rate 

≤ 0.75 m/s > 0.75 m/s 

6.1.3 Measurements 

Measurements collected during the test support the following: 

1. Determine whether a warning was given 
33 

2. Determine the desired location of a warning given the conditions 

3. Determine the amount of time the warning gives driver 

6.1.3.1 Time of Warning 

See section 2.3.9. 

6.1.3.2 Longitudinal Speed 

See section 2.2.2. 

6.1.3.3 Distance to Road Edge 

See section 2.2.7. 

6.1.3.4 Lateral Velocity 

See section 2.2.4. 

6.1.4 Test Procedure 

The general procedure for the test repeats a series of road departure trajectories depicted 

in Figure 19. 

6.1.4.1 Pre-Test Procedures 

The procedures before the test are: 

1. Ensure road geometry meets the test condition. Measure the geometry if it is 

unknown (see Appendix A, Methods for Determining Road Dimensions and 

Geometry). 

2. Ensure lane marker characteristics meet the test conditions (see sections 2.1.1-

2.1.12). 

3. Check speedometer accuracy (see section 2.2.2). 

4. Verify IMS camera calibration according to recommendations in [5]. Repeat 

camera calibration if camera has moved. 

5. Ensure microphone detects warning system alerts and driver speech. 

6. Ensure recording system is working properly. 

7. Ensure GPS has sufficient satellite signals. 

8. Verify road boundary for test (i.e., outer lane marker plus AMR) and practice 

vehicle trajectories (speeds, departure rate, etc.) until accomplished safely and 

reliably. 

6.1.4.2 Test Procedures 

The procedures during the test are: 

1. Achieve speed. The driver brings the vehicle to the prescribed speed and sets the 

cruise control at the speed. 

2. Set turn signal. The driver runs the first departure with turn signal active. Since this 

departure will be a True Negative, the operator documents the departure time. The 

operator runs the remaining departures without activating the turn signal. 
34 

3. Execute departure. The driver steers toward the road boundary at the prescribed 

departure rate (high or low) until the road boundary is crossed. See section 2.2.8 for 

a method to achieve the prescribed departure rate. 

4. Record departure rate. The assistant records the estimated departure rate as either 

low or high. 

5. Go to start of next departure trajectory. The driver steers the vehicle back onto the 

road for the next departure. 

6. The driver repeats the departure trajectories to fulfill the following conditions: 

a. Five left departures at the low departure rate 

b. Five right departures at the low departure rate 

c. Five left departures at the high departure rate 

d. Five right departures at the high departure rate 

e. One right departure at the high departure rate with the right turn signal on. 

f. One left departure at the high departure rate with the left turn signal on. 

7. Repeat steps 1 – 6 for the middle prescribed speed. 

8. Repeat steps 1 – 6 for the high-prescribed speed. 

6.1.4.3 Post-Test Procedures 

The procedures after the test consist of the following steps: 

1. Verify IMS camera orientation has not changed. Repeat tests if changed. 

6.1.5 Evaluation Methods 

Use the following methods to evaluate warning system performance. 

6.1.5.1 Rate System Response 

Examine the video and audio data and rate each warning scenario. 

For the road departure events: 

The rating is a true positive if the system responds with a warning before the road 

boundary is crossed. 

The rating is a false negative if the system does not respond with a warning before 

the road boundary is crossed. 

For the cross dashed-line events: 

The rating is a true positive if the system responds with a warning before the road 

boundary is crossed and the turn signal is inactive. 

The rating is a false positive if the system responds with a warning before the 

road boundary is crossed and the turn signal is active. 
35 

6.1.5.2 Desired Location of Warning 

For each test run, the evaluator determines the desired location for the warning. The 

desired location depends on the measured departure rate and the forward speed. 

1. Locate the time of warning in the video data (e.g., locate first video frame alert). 

2. Measure lateral position and lateral velocity to the road edge at time of warning. 

3. Use equation (1) in section 5.1.1 to determine the desired location for a warning on a 

straight road. 

6.1.5.3 Timeliness of Warning 

For each test run, the evaluator determines whether the warning is early, late or on time

using steps described in section 5.1.1. The results of the timeliness evaluations are 

accumulated according to section 5.3. 

6.1.6 Reporting 

The evaluator compiles the test reports in accordance with the following tables. 

Name of Test Departure on One-Way Straight Road 

with Fixed Available Maneuver Room 

Date of Test 

Warning System ID Name and Version Number 
36 

Test Run Results 

Factors Response

Speed 

mph 

Departure 

Rate m/s 

Direction Signal # of 

runs

Run 

# 

CR

T/F

vf 

mph

vl 

m/s

ym 

m

yw 

m

T 

OT/E/L 

40 ≤ 0.75 Left No 5 1 

" " " " 2... 

40 ≤ 0.75 Right No 5 

40 > 0.75 Left No 5 

40 > 0.75 Right No 5 

40 > 0.75 Left On 1 

55 ≤ 0.75 Left No 5 

55 ≤ 0.75 Right No 5 

55 > 0.75 Left No 5 

55 > 0.75 Right No 5 

55 > 0.75 Left On 1 

55 > 0.75 Right On 1 

70 ≤ 0.75 Left No 5 

70 ≤ 0.75 Right No 5 

70 > 0.75 Left No 5 

70 > 0.75 Right No 5 

70 > 0.75 Left On 1 

70 > 0.75 Right On 1 

CR = System gave correct response (T) or failed to give correct response (F). Refer to 

subsection 1.1 above to determine correct response. 

vf = measured vehicle forward speed 

vl = measured vehicle lateral speed (departure rate) 

ym = measured lateral distance between the vehicle front tire and the road boundary at 

the time of warning 

yw = the desired lateral distance at the time of warning using equation (1) 

T = Timeliness of warning OnTime, Early or Late 

Test Run Summary Results (see section 5.3) 

Combined Results for 

all runs 

# of 

runs 

# 

CR 

# 

OT 

# 

E 

# 

L 

% 

OT

% 

E 

% 

L 

Date/time of test runs 

False Alarm Incident Report 

Run 

#

Probable Cause 

1 Example: shadows on road misinterpreted as road edge 

... ... 

Lane Change with Turn Signal Event Evaluation 

Number of Lane 

Change Tests 

Number of Incorrect 

Responses 

Number of Correct 

Responses 

# # # 
37 
38 

6.2 Two-Way Straight Road (Default minimum AMR) 

The Two-Way Straight Road (with default minimum AMR) test assesses the performance 

of the lateral drift warning function for road departures on undivided straight roads. This 

scenario falls under the "going straight on undivided non-freeway with two lanes at nonjunction" scenario identified in the NHTSA test scenario report as one of the major 

settings for road departure crashes [3]. 

The figure below illustrates the test. The road boundary depends on the type of marker 

the vehicle first encounters during the departure trajectory. A solid marker prohibits 

passing. The road boundary is the left edge of the solid marker and the available 

maneuver room is zero. A dashed marker allows passing and indicates a wider lane but 

no AMR. The warning system issues a departure alert only if the turn signal is not active. 

This test has no available maneuver room because the adjacent lane may have undetected 

on-coming traffic. The double solid lane case is similar to the solid/dashed marker in 

figure A. 

A B

1

Road

Boundary

1

Road

Boundary

Figure 20. Vehicle trajectory during test 

6.2.1 Events and System Response 

The following table defines the events for this test and the correct warning signal the 

system shall provide. See the figure above to locate the event (e.g., Id A1 is label 1 in 

figure A). 
39 

Id Event Correct Response 

A1 Road Departure with 

passing not permitted 

1. Issue road departure warning 

B1 Road Departure with 

passing permitted 

1. Issue no warning if the correct turn signal active. 

2. Issue a road departure warning if no turn signal 

active or incorrect turn signal active. 

6.2.2 Test Conditions 

The conditions for this test include the following. 

6.2.2.1 Road Geometry 

The road geometry for the test is the following: 

Road Geometry Dimension 

Straight (defined using radius of curvature) > 1000 m 

Appendix A, Methods for Determining Road Dimensions and Geometry, contains the 

recommended method to verify the geometry. 

6.2.2.2 Available Maneuver Room 

In this test, the warning system recognizes the road edge but cannot determine if there is 

on-coming traffic. Therefore, the AMR equals zero. 

Available Maneuver Room Comment 

0 cm Not allowed to cross over the lane marker 

6.2.2.3 Speed 

The vehicle speeds during the tests cover the warning system operating range. 

Low Speed Medium Speed High Speed 

64 km/h (40 mph) 89 km/h (55 mph) 113 km/h (70 mph) 

6.2.2.4 Departure Rate 

The vehicle departure rates during the tests fall within two ranges. These rates are 

comparable to the rates suggested in the ROR report and in the ISO standard for testing 

lateral drift warning systems. 

Low Departure Rate High Departure Rate 

≤ 0.75 m/s > 0.75 m/s 

6.2.3 Measurements 

Measurements collected during the test support the following: 

1. Determine whether a warning was given 

2. Determine the desired location of a warning given the conditions 
40 

3. Determine the amount of time the warning gives driver 

6.2.3.1 Time of Warning 

See section 2.3.9. 

6.2.3.2 Longitudinal Speed 

See section 2.2.2. 

6.2.3.3 Distance to Road Edge 

See section 2.2.7. 

6.2.3.4 Lateral Velocity 

See section 2.2.4. 

6.2.4 Test Procedure 

The general procedure for the test is to repeat a series of road departure trajectories 

depicted in Figure 20. 

6.2.4.1 Pre-Test Procedures 

The procedures before the test are: 

1. Ensure road geometry meets the test condition. Measure the geometry if it is 

unknown (see Appendix A, Methods for Determining Road Dimensions and 

Geometry). 

2. Ensure lane marker characteristics meet the test conditions (see sections 2.1.1-

2.1.12). 

3. Check speedometer accuracy (see section 2.2.2). 

4. Verify IMS camera calibration according to recommendations in [5]. Repeat 

camera calibration if camera has moved. 

5. Ensure microphone detects warning system alerts and driver speech. 

6. Ensure recording system is working properly. 

7. Ensure GPS has sufficient satellite signals. 

8. Verify road boundary for test (i.e., outer lane marker plus AMR) and practice 

vehicle trajectories (speeds, departure rate, etc.) until accomplished safely and 

reliably. 

6.2.4.2 Test Procedures 

The procedures during the test are: 

1. Achieve speed. The driver brings the vehicle to the prescribed speed and sets the 

cruise control at the speed. 

2. Set turn signal. The driver runs one departure with turn signal active and documents 

the departure time. The driver runs the remaining departures with the turn signal 

inactive. 
41 

3. Execute departure. The driver steers toward the road boundary at the prescribed 

departure rate (high or low) until the road boundary is crossed. See section 2.2.8 for 

a method to achieve the prescribed departure rate. 

4. Record departure rate. The assistant records the estimated departure rate as either 

low or high. 

5. Go to start of next departure trajectory. The driver steers the vehicle back onto the 

road for the next departure 

6. Repeat steps 1-5 for: 

a. Five left departures in no passing zone at the low departure rate 

b. Five left departures in no passing zone at the high departure rate 

c. Five left departures in passing zone at the low departure rate 

d. Five left departures in passing zone at the high departure rate 

e. One left departure in passing zone at the high departure rate with turn signal on. 

7. Repeat steps 1 - 6 for the middle prescribed speed. 

8. Repeat steps 1 - 6 for the high prescribed speed. 

6.2.4.3 Post-Test Procedures 

The procedures after the test are: 

1. Verify IMS camera orientation has not changed. Repeat tests if changed. 

6.2.5 Evaluation Methods 

Use the following methods to evaluate warning system performance. 

6.2.5.1 Rate System Response 

Examine the video and audio data and rate each warning scenario. 

For the no passing permitted road departure event: 

The rating is a true positive if the system responds with a warning before the road 

boundary is crossed. 

The rating is a false negative if the system does not respond with a warning before 

the road boundary is crossed. 

For the passing permitted road departure event: 

The rating is a true positive if the system responds with a warning before the road 

boundary is crossed and the turn signal is inactive. 

The rating is a false positive if the system responds with a warning before the 

road boundary is crossed and the turn signal is active. 
42 

6.2.5.2 Desired Location of Warning 

For each test run, the evaluator determines the desired location of the warning. The 

desired warning location varies with the departure rate and the forward speed. 

1. Locate the time of warning in the video data (e.g., the first video frame with the alert). 

2. Measure lateral position and lateral velocity to the road edge at the time of the 

warning. 

3. With equation (1) in section 5.1.1, determine the desired location for a warning on a 

straight road. 

6.2.5.3 Timeliness of Warning 

For each test run, the evaluator determines whether the warning is early, late or on time

using steps described in section 5.1.1. The results of the timeliness evaluations are 

accumulated according to section 5.3. 

6.2.6 Reporting 

The evaluator completes the following tables with information from each test. 

Name of Test Departure on Un-Divided (Two-Way) 

Straight Road with No AMR 

Date of Test 

Warning System ID Name and Version Number 

Test Run Results 

Factors Response

Speed 

mph 

Departure 

Rate m/s 

Direction Pass 

Zone 

Signal # of 

runs 

Run 

# 

CR 

T/F 

vf 

mph

vl 

m/s

ym 

m

yw 

m

T 

OT/E/L 

40 ≤ 0.75 Left NP None 5 1 

" " " " " " 2... 

40 > 0.75 Left NP None 5 

40 ≤ 0.75 Left P None 5 

40 > 0.75 Left P None 5 

40 > 0.75 Left P ON 1 

55 ≤ 0.75 Left NP None 5 

55 > 0.75 Left NP None 5 

55 ≤ 0.75 Left P None 5 

55 > 0.75 Left P None 5 

55 > 0.75 Left P ON 1 

70 ≤ 0.75 Left NP None 5 

70 > 0.75 Left NP None 5 

70 ≤ 0.75 Left P None 5 

70 > 0.75 Left P None 5 

70 > 0.75 Left P ON 1 

CR = System gave correct response (T) or failed to give correct response (F). Refer to 

subsection 1.1 above to determine correct response. 
43 

vf = vehicle forward speed 

vl = vehicle lateral speed (departure rate) 

ym = the measured lateral distance between the vehicle front tire and the road boundary 

at the time of warning 

yw = the desired lateral distance at the time of warning using equation (1) 

T = Timeliness of warning (early, late or on time) 

Test Run Summary Results (see section 5.3) 

Combined Results for 

all runs 

# of 

runs 

# 

CR 

# 

OT 

# 

E 

# 

L 

% 

OT

% 

E 

% 

L 

Date/time of test runs 

False Alarm Incident Report 

Run 

#

Probable Cause 

1 Example: shadows on road misinterpreted as road edge 

... ... 

Lane Change with Turn Signal Event Evaluation 

Number of Lane 

Change Tests 

Number of Incorrect 

Responses 

Number of Correct 

Responses 

# # # 

6.3 Curved Road (Default minimum AMR) 

The Curved Road (default minimum AMR) test examines the performance of the lateral 

drift warning function for road departures on a curved road. This scenario is not part of 

the curve speed warning function. During the Curved Road test, the vehicle travels within 

the established speed limit for the roadway. The test uses three curves of different radii: 

a slow speed curve, a medium speed curve and a high-speed curve. 

In this scenario, the vehicle travels straight until a road departure occurs (Figure 21). The 

driver uses a guide target to maintain the straight road trajectory during the departure. 

The test area must have sufficient room for safe recovery after the road departure. 

 

Run the tests in the opposite direction to test a left-side departure (e.g. for a divided 

highway). 
44 

Figure 21. Vehicle trajectory during test 

6.3.1 Events and System Response 

The following table defines the event for this test and the correct warning signal 

response. The numeral in Figure 21 above displays the proper trajectory for the event. 

Id Event Correct Response 

1 Crossed solid line Issue crossed solid line warning 

6.3.2 Test Conditions 

The conditions for this test include the following. 

6.3.2.1 Road Geometry 

The curve radius for this test should be appropriate for the low speed, medium speed and 

high-speed conditions. The following equation calculates the curve radius for each speed 

condition using lateral acceleration limits (alat) from section 2.3.5. 

alat

v

r

2

=

To simplify setting up the test, a curve radius may fall within a range of radii by using the 

lateral acceleration limits for sensitivities 2 and 4. 

Road Geometry Dimension 

Low speed curve, 64 km/h (40 mph) 91 m - 136 m 
45 

Medium speed curve, 89 km/h (55 mph) 172 m - 257 m 

Low speed curve, 113 km/h (70 mph) 278 m - 417 m 

Appendix A, Methods for Determining Road Dimensions and Geometry, contains the 

recommended method to verify the geometry. 

6.3.2.2 Available Maneuver Room 

In this test, the warning system recognizes the road edge but cannot determine if there is 

additional AMR. Therefore, the system should assume a default minimum AMR. 

Available Maneuver Room Comment 

15 cm (6 in) Default minimum AMR 

6.3.2.3 Speed 

The vehicle speeds during the tests cover the warning system operating range. The 

operator uses appropriate curve radii as the trajectory speed changes. 

Low Speed Medium Speed High Speed 

64 km/h (40 mph) 89 km/h (55 mph) 113 km/h (70 mph) 

6.3.3 Measurements 

Measurements collected during the test support the following: 

1. Determine whether a warning was given 

2. Determine the desired location of a warning given the conditions 

3. Determine the amount of time the warning gives driver 

6.3.3.1 Time of Warning 

See section 2.3.9. 

6.3.3.2 Longitudinal Speed 

See section 2.2.2. 

6.3.3.3 Distance to Road Edge 

See section 2.2.7. 

6.3.3.4 Distance to Curve Entry Point 

See section 2.2.10. 

6.3.4 Test Procedure 

In this test, the driver repeats a series of road departure trajectories as depicted in Figure 

21 above. 

6.3.4.1 Pre-Test Procedures 

The procedures before the test are: 
46 

1. Ensure road geometry meets the test condition. Measure the geometry if it is 

unknown (see Appendix A, Methods for Determining Road Dimensions and 

Geometry). 

2. Ensure lane marker characteristics meet the test conditions (see sections 2.1.1-

2.1.12). 

3. Check speedometer accuracy (see section 2.2.2). 

4. Verify IMS camera calibration according to recommendations in [5]. Repeat 

camera calibration if camera has moved. 

5. Ensure microphone detects warning system alerts and driver speech. 

6. Ensure recording system is working properly. 

7. Ensure GPS has sufficient satellite signals. 

8. Verify road boundary for test (i.e., outer lane marker plus AMR) and practice 

vehicle trajectories (speeds, departure rate, etc.) until accomplished safely and 

reliably. 

6.3.4.2 Test Procedures 

The procedures during the test are: 

1. Achieve speed. The driver brings the vehicle to the prescribed speed (low speed 

curve is 64 km/h (40 mph)). The driver uses the cruise control if available. 

2. Straighten vehicle before curve entry. Before entering the curve, the driver centers 

the vehicle in the lane using the lane markers as a visual guide. The vehicle remains 

centered into the curve. 

3. Maintain straight trajectory into the curve. As the vehicle enters the curve, the 

driver uses a guide target to maintain a straight trajectory through the departure. 

4. Depart road. The driver crosses over the lane marker and then recovers from the 

departure. 

5. Repeat the departure trajectories for: 

a. Five right departures 

b. Five left departures 

6. Repeat steps 1 - 5 for the middle speed curve. 

7. Repeat steps 1 - 5 for the high-speed curve. 

6.3.4.3 Post-Test Procedures 

The procedures after the test are: 

1. Verify IMS camera orientation has not changed. Repeat tests if changed. 

6.3.5 Evaluation Methods 

Use the following methods to evaluate warning system performance. 

6.3.5.1 Rate System Response 

Examine the video and audio data and rate each warning scenario. 
47 

The rating is a true positive if the system responds with a warning before the road 

boundary is crossed. 

The rating is a false negative if the system does not respond with a warning before 

the road boundary is crossed. 

6.3.5.2 Desired Location of Warning 

For each test run, the evaluator determines the desired location of the warning. This will 

vary depending on the measured departure rate and forward speed. 

1. Locate the time of warning in the video data (for example, by locating video frame 

where alert is first displayed). 

2. Measure lateral position to the road edge at time of warning. 

3. Use equation (4) in section 5.1.2 to determine the desired location for a warning on a 

curve. 

6.3.5.3 Timeliness of Warning 

For each test run, the evaluator determines whether the warning is early, late or on time

using steps described in section Error! Reference source not found.. The results of the 

timeliness evaluations are accumulated according to section 5.3. 

6.3.6 Reporting 

The evaluator completes the following tables from the data from each test. 

Name of Test Departure on Divided Curved Road with Fixed Available 

Maneuver Room 

Date of Test 

Warning System ID Name and Version Number 

Test Run Results 

Factors Results

Curve Speed 

mph 

Direction # of 

runs Run 

# 

CR 

T/F 

vf 

mph

ym 

m

xw 

m

T 

OT/E/L 

LS 40 Left 5 1 

" " " 2... 

LS 40 Right 5 

MS 55 Left 5 

MS 55 Right 5 

HS 70 Left 5 

HS 70 Right 5 

Curve = Low speed curve, medium speed curve or high speed curve 

CR = System gave correct response (T) or failed to give correct response (F). Refer to 

subsection 1.1 above to determine correct response. 

vf = vehicle forward speed 
48 

ym = the measured lateral distance between the vehicle front tire and the road boundary 

at the time of warning 

xw = the desired distance to curve entry point at the time of warning using equation (4) 

T = Timeliness of warning (early, late or on time) 

Test Run Summary Results (see section 5.3) 

Combined Results for 

all runs 

# of 

runs 

# 

CR 

# 

OT 

# 

E 

# 

L 

% 

OT

% 

E 

% 

L 

Date/time of test runs 

False Alarm Incident Report 

Run 

#

Probable Cause 

1 Example: shadows on road misinterpreted as road edge 

... ... 
49 

7 Tests for Departures on Roads with Maximum AMR

The Departure on Roads with Maximum AMR tests evaluate warning system response to 

road departures where a shoulder provides increased available maneuver room. These 

tests do not assess the ability of the system to detect obstacles on the shoulder. 

Therefore, these tests do not provide a complete assessment of a fully functional warning 

system. A warning system must also pass the “Tests for Departures Toward an 

Obstacle” that appear in section 8. 

These tests assess the capability of a warning system to detect the shoulder and measure 

its width. The transition between on-road and off-road must have some discriminating 

visual property, such as color or texture. The tests employ two off-road materials: dirt 

and artificial grass. The off-road material lies upon a paved surface so that the vehicle 

may depart from the road with minimal risk. 

The tests employ two shoulder widths. The large shoulder width is twice the maximum 

AMR. The system should detect the large shoulder but limit the AMR to the maximum 

in order to provide consistent warnings. The small shoulder is half the maximum AMR. 

The system should detect the small shoulder and issue the warning earlier than for a large 

shoulder. An earlier warning indicates the system successfully detected the decreased 

shoulder width. 

The test scenarios include departures on a straight road and on a curved road. 
50 

7.1 Straight Road with Shoulder (Maximum AMR) 

The Straight Road with Shoulder test assesses the warning system’s ability to detect the 

shoulder width and to adjust the warning location on a straight road departure. 

The figure below illustrates the test scenario. The left-side departure is similar. 

Figure 22. Straight Road with Shoulder Test Trajectory 

7.1.1 Events and System Response 

The following table defines the events for this test and the correct warning response. See 

the figure above to locate the event (e.g., Id A1 is label 1 in figure A). 

Id Event Correct Response 

A1 Road departure 1. Issue road departure warning 

B1 Same as A1 1. Same as A1, except earlier 

7.1.2 Test Conditions 

The conditions for this test include the following. 

7.1.2.1 Road Geometry 

The road geometry for the test is: 

Road Geometry Dimension 

Straight (defined using radius of curvature) > 1000 m 
51 

Appendix A, Methods for Determining Road Dimensions and Geometry, contains the 

recommended method to verify the road geometry. 

7.1.2.2 Available Maneuver Room 

In this test, shoulder width affects the AMR. However, the test limits the AMR to a 

default maximum value to prevent large variations in warning location due to large 

variations in shoulder width. 

Available Maneuver Room Comment 

1 m (39 in) Default maximum AMR 

7.1.2.3 Speed 

The vehicle speeds during the tests cover the warning system operating range. 

Low Speed Medium Speed High Speed 

64 km/h (40 mph) 89 km/h (55 mph) 113 km/h (70 mph) 

7.1.2.4 Departure Rate 

The vehicle departure rates during the tests fall within two ranges. These rates are 

comparable to the rates suggested in the ROR report and in the ISO standard for testing 

lateral drift warning systems. 

Low Departure Rate High Departure Rate 

≤ 0.75 m/s > 0.75 m/s 

7.1.2.5 Shoulder Width 

This test uses two shoulder widths. The small shoulder is one half the default maximum 

AMR and the large shoulder is twice the AMR. Update these values if the default 

minimum or maximum AMR changes. 

Shoulder Width Name Dimension 

Small Shoulder 0.5 m (19.5 in) 

Large Shoulder 2 m 

7.1.2.6 Off-Road Material 

These tests use two types of material to simulate off-road surfaces. The operator places 

the material on a wide shoulder to reduce the visual width of the shoulder to the widths 

specified above. 

Off-road Characteristics 

Dirt Brown or variations. 

Grass Green artificial grass material 
52 

7.1.3 Measurements 

Measurements collected during the test support the following: 

1. Determine whether a warning was given 

2. Determine the desired location of a warning given the conditions 

3. Determine the amount of time the warning gives driver 

7.1.3.1 Time of Warning 

See section 2.3.9. 

7.1.3.2 Longitudinal Speed 

See section 2.2.2. 

7.1.3.3 Distance to Road Edge 

See section 2.2.7. 

7.1.3.4 Lateral Velocity 

See section 2.2.4. 

7.1.4 Test Procedure 

The test repeats a series of road departure trajectories as depicted in Figure 22. 

7.1.4.1 Pre-Test Procedures 

The procedures before the test are: 

1. Ensure road geometry meets the test condition. Measure the geometry if it is 

unknown (see Appendix A, Methods for Determining Road Dimensions and 

Geometry). 

2. Ensure lane marker characteristics meet the test conditions (see sections 2.1.1-

2.1.12). 

3. Check speedometer accuracy (see section 2.2.2). 

4. Verify IMS camera calibration according to recommendations in [5]. Repeat 

camera calibration if camera has moved. 

5. Ensure microphone detects warning system alerts and driver speech. 

6. Ensure recording system is working properly. 

7. Ensure GPS has sufficient satellite signals. 

8. Verify road boundary for test (i.e., outer lane marker plus AMR) and practice 

vehicle trajectories (speeds, departure rate, etc.) until accomplished safely and 

reliably. 

9. Set AMR width with dirt off-road material. 

7.1.4.2 Test Procedures 

The procedures during the test are: 
53 

1. Achieve speed. The driver brings the vehicle to the prescribed speed. The driver 

may use cruise control if the vehicle is properly equipped. 

2. Execute departure. The driver steers toward the road boundary at the prescribed 

departure rate (high or low) until the road boundary (dirt or grass) is crossed. See 

section 2.2.8 for a method to achieve the prescribed departure rate. 

3. Record departure rate. The assistant records the estimated departure rate as either 

low or high. 

4. Go to start of next departure trajectory. The driver steers the vehicle back onto the 

road for the next departure. 

5. Repeat steps 1-4 for: 

a. Five right departures at the low departure rate 

b. Five right departures at the high departure rate 

6. Repeat steps 1 - 5 for the prescribed middle speed. 

7. Repeat steps 1 - 5 for the prescribed high speed. 

8. Repeat steps 1 – 7 with the small shoulder width. 

9. Repeat steps 1 – 8 for grass off-road material. 

7.1.4.3 Post-Test Procedures 

The procedures after the test are: 

1. Verify IMS camera orientation has not changed. Repeat tests if changed. 

7.1.5 Evaluation Methods 

Use the following methods to evaluate warning system performance. 

7.1.5.1 Rate System Response 

Examine the video and audio data and rate each warning scenario. 

The rating is a true positive if the system responds with a warning before the road 

boundary is crossed. 

The rating is a false negative if the system does not respond with a warning before 

the road boundary is crossed. 

7.1.5.2 Desired Location of Warning 

For each test run, the evaluator determines the desired location of the warning. The 

desired location varies with the lane curvature and the forward speed. 

1. Locate the time of warning in the video data (e.g., first video frame with an alert). 

2. Measure lateral position and lateral velocity to the road edge at time of warning. 

3. Use equation (1) in section 5.1.1 to determine the desired location for a warning on a 

straight road. 
54 

7.1.5.3 Timeliness of Warning 

For each test run, the evaluator determines whether the warning is early, late or on time

using steps described in section 5.1.1. The results of the timeliness evaluations are 

accumulated according to section 5.3. 

7.1.6 Reporting 

The evaluator completes the following tables from the data in each test. 

Name of Test Departure on Straight Road with Shoulder 

Date of Test 

Warning System ID Name and Version Number 

Test Run Results 

Factors Results

Offroad 

Mat. 

Speed 

mph 

Departure 

Rate m/s 

Direction Signal # of 

runs Run 

# 

CR 

T/F 

vf 

mph

vl 

m/s

ym 

m

yw 

m

T 

OT/E/L 

Dirt 40 ≤ 0.75 Left No 5 1 

" " " " " 2... 

Dirt 40 ≤ 0.75 Right No 5 

Dirt 40 > 0.75 Left No 5 

Dirt 40 > 0.75 Right No 5 

Dirt 40 > 0.75 Left On 1 

Dirt 55 ≤ 0.75 Left No 5 

Dirt 55 ≤ 0.75 Right No 5 

Dirt 55 > 0.75 Left No 5 

Dirt 55 > 0.75 Right No 5 

Dirt 55 > 0.75 Left On 1 

Dirt 55 > 0.75 Right On 1 

Dirt 70 ≤ 0.75 Left No 5 

Dirt 70 ≤ 0.75 Right No 5 

Dirt 70 > 0.75 Left No 5 

Dirt 70 > 0.75 Right No 5 

Dirt 70 > 0.75 Left On 1 

Dirt 70 > 0.75 Right On 1 

Grass 40 ≤ 0.75 Left No 5 

Grass 40 ≤ 0.75 Right No 5 

Grass 40 > 0.75 Left No 5 

Grass 40 > 0.75 Right No 5 

Grass 40 > 0.75 Left On 1 

Grass 55 ≤ 0.75 Left No 5 

Grass 55 ≤ 0.75 Right No 5 

Grass 55 > 0.75 Left No 5 

Grass 55 > 0.75 Right No 5 

Grass 55 > 0.75 Left On 1 

Grass 55 > 0.75 Right On 1 
55 

Grass 70 ≤ 0.75 Left No 5 

Grass 70 ≤ 0.75 Right No 5 

Grass 70 > 0.75 Left No 5 

Grass 70 > 0.75 Right No 5 

Grass 70 > 0.75 Left On 1 

Grass 70 > 0.75 Right On 1 

CR = System gave correct response (T) or failed to give correct response (F). Refer to 

subsection 1.1 above to determine correct response. 

vf = measured vehicle forward speed 

vl = measured vehicle lateral speed (departure rate) 

ym = measured lateral distance between the vehicle front tire and the road boundary at 

the time of warning 

yw = the desired lateral distance at the time of warning using equation (1) 

T = Timeliness of warning (early, late or on time) 

Test Run Summary Results (see section 5.3) 

Combined Results for 

all runs 

# of 

runs 

# 

CR 

# 

OT 

# 

E 

# 

L 

% 

OT

% 

E 

% 

L 

Date/time of test runs 

False Alarm Incident Report 

Run 

#

Probable Cause 

1 Example: shadows on road misinterpreted as road edge 

... ... 
56 

7.2 Curved Road with Shoulder (Maximum AMR) 

The Curved Road with Shoulder test assesses the warning system’s ability to detect the 

shoulder width and to adjust the warning location on a curved road departure. This test is 

similar to the test in section 7.1. 

The figure below illustrates the test scenario. The left-side departure test uses a right turn 

curve. 

Figure 23. Curved Road with Shoulder Test Trajectory 

7.2.1 Events and System Response 

The following table defines the events for this test and the correct warning signal the 

system shall provide. See the figure above to locate the event. 

Id Event Correct Response 

A1 Road departure 1. Issue road departure warning 

B1 Same as A1 1. Same as A1 except earlier 

7.2.2 Test Conditions 

The conditions for this test include the following. 
57 

7.2.2.1 Road Geometry 

The curve radius for this test is appropriate for the low speed, medium speed and highspeed conditions. The following equation calculates the curve radius for each speed 

condition using lateral acceleration limits (alat) from section 2.3.5. 

lat a

v

r

2

=

For the test, the curve radius falls within a range of radii by using the lateral acceleration 

limits for sensitivities 2 and 4. 

Road Geometry Dimension 

Low speed curve, 64 km/h (40 mph) 91 m - 136 m 

Medium speed curve, 89 km/h (55 mph) 172 m - 257 m 

Low speed curve, 113 km/h (70 mph) 278 m - 417 m 

Appendix A, Methods for Determining Road Dimensions and Geometry, contains the 

recommended method to verify the geometry. 

7.2.2.2 Available Maneuver Room 

In this test, shoulder width affects the AMR. However, the test limits the AMR to a 

default maximum value to prevent large variations in warning location due to large 

variations in shoulder width. 

Available Maneuver Room Comment 

1 m (39 in) Default maximum AMR 

7.2.2.3 Speed 

The vehicle speeds during the tests cover the warning system operating range. 

Low Speed Medium Speed High Speed 

64 km/h (40 mph) 89 km/h (55 mph) 113 km/h (70 mph) 

7.2.2.4 Shoulder Width 

This test uses two shoulder widths. The small shoulder is one half the maximum AMR 

and the large shoulder is twice the AMR. Update these values if the default minimum or 

maximum AMR changes. 

Shoulder Width Name Shoulder Width Dimension 

Small Shoulder 0.5 m (19.5 in) 

Large Shoulder 2 m 

7.2.2.5 Off-Road Material 

These tests use two types of material to simulate off-road surfaces. The operator places 

the material on a wide shoulder to reduce the visual width of the shoulder to the widths 

specified above. 
58 

Off-road Characteristics 

Dirt Brown or variations. 

Grass Green artificial grass material 

7.2.3 Measurements 

Measurements collected during the test support the following: 

1. Determine whether a warning was given 

2. Determine the desired location of a warning given the conditions 

3. Determine the amount of time the warning gives driver 

7.2.3.1 Time of Warning 

See section 2.3.9. 

7.2.3.2 Longitudinal Speed 

See section 2.2.2. 

7.2.3.3 Distance to Road Edge 

See section 2.2.7. For this test, the road edge is the base of the barrier. 

7.2.3.4 Distance to Curve Entry Point 

See section 2.2.10. 

7.2.4 Test Procedure 

The test repeats a series of road departure trajectories as depicted in Figure 23. 

7.2.4.1 Pre-Test Procedures 

The procedures before the test are: 

1. Ensure road geometry meets the test condition. Measure the geometry if it is 

unknown (see Appendix A, Methods for Determining Road Dimensions and 

Geometry). 

2. Ensure lane marker characteristics meet the test conditions (see sections 2.1.1-

2.1.12). 

3. Check speedometer accuracy (see section 2.2.2). 

4. Verify IMS camera calibration according to recommendations in [5]. Repeat 

camera calibration if camera has moved. 

5. Ensure microphone detects warning system alerts and driver speech. 

6. Ensure recording system is working properly. 

7. Ensure GPS has sufficient satellite signals. 

8. Verify road boundary for test (i.e., outer lane marker plus AMR) and practice 

vehicle trajectories (speeds, departure rate, etc.) until accomplished safely and 

reliably. 

9. Set the AMR width with dirt off-road material. 
59 

7.2.4.2 Test Procedures 

The procedures during the test are: 

1. Achieve speed. The driver brings the vehicle to the prescribed speed. The driver 

may use cruise control if the vehicle is properly equipped. 

2. Straighten vehicle and center vehicle in the lane before entering the curve. The 

driver centers the vehicle in the lane using the lane markers as a visual guide. The 

vehicle remains in the center until the start of the curve. 

3. Maintain straight trajectory into the curve. As the vehicle enters the curve, the 

driver uses a guide target to maintain the straight lane trajectory through the 

departure. 

4. Depart road. The driver crosses over the lane marker and then recovers from the 

departure. 

5. Repeat steps 1-4 for: 

a. Five right departures. 

b. Five left departures. 

6. Repeat steps 1 - 5 for the middle speed curve. 

7. Repeat steps 1 - 5 for the high-speed curve. 

8. Repeat steps 1 - 7 with the small shoulder width. 

9. Repeat steps 1 - 8 with the grass off-road material. 

7.2.4.3 Post-Test Procedures 

The procedures after the test are: 

1. Verify IMS camera orientation has not changed. Repeat tests if changed. 

7.2.5 Evaluation Methods 

Use the following methods to evaluate warning system performance. 

7.2.5.1 Rate System Response 

Examine the video and audio data and rate each warning scenario. 

The rating is a true positive if the system responds with a warning before the road 

boundary is crossed. 

The rating is a false negative if the system does not respond with a warning before 

the road boundary is crossed. 

7.2.5.2 Desired Location of Warning 

For each test run, the evaluator determines the desired location of the warning. The 

desired location varies with the departure rate and forward speed. 

1. Locate the time of warning in the video data (for example, by locating video frame 

where alert is first displayed). 

2. Measure lateral position and lateral velocity to the road edge at time of warning. 
60 

3. Use equation (4) in section 5.1.2 to determine the desired location for a warning on a 

curve. 

7.2.5.3 Timeliness of Warning 

For each test run, the evaluator determines whether the warning is early, late or on time

using steps described in section Error! Reference source not found.. The results of the 

timeliness evaluations are accumulated according to section 5.3. 

7.2.6 Reporting 

The evaluator completes the following tables from the data in each test. 

Name of Test Departure on Curved Road with Shoulder 

Date of Test 

Warning System ID Name and Version Number 

Test Run Results 

Factors Results

Offroad 

Mat. 

Curve Speed 

mph 

Direction # of 

runs Run 

# 

CR 

T/F 

vf 

mph

ym 

m

xw 

m

T 

OT/E/L 

Dirt LS 40 Left 5 1 

" " " " 2... 

Dirt LS 40 Right 5 

Dirt MS 55 Left 5 

Dirt MS 55 Right 5 

Dirt HS 70 Left 5 

Dirt HS 70 Right 5 

Grass LS 40 Left 5 

Grass LS 40 Right 5 

Grass MS 55 Left 5 

Grass MS 55 Right 5 

Grass HS 70 Left 5 

Grass HS 70 Right 5 

Curve = Low speed curve, medium speed curve and high speed curve 

CR = System gave correct response (T) or failed to give correct response (F). Refer to 

subsection 1.1 above to determine correct response. 

vf = vehicle forward speed 

ym = the measured lateral distance between the vehicle front tire and the road boundary 

at the time of warning 

xw = the desired distance to curve entry point at the time of warning using equation (4) 

T = Timeliness of warning (early, late or on time) 

Test Run Summary Results (see section 5.3) 

Combined Results for 

all runs 

# of 

runs 

# 

CR 

# 

OT 

# 

E 

# 

L 

% 

OT

% 

E 

% 

L 

Date/time of test runs 
61 

False Alarm Incident Report 

Run 

#

Probable Cause 

1 Example: shadows on road misinterpreted as road edge 

... ... 
62 

8 Tests for Departures Toward an Obstacle

These tests evaluate warning system response to road departures toward an obstacle on 

the shoulder. The warning system detects the obstacle, decreases the available maneuver 

room, and issues a warning based on the location of the obstacles. These tests do not 

assess the system’s ability to determine whether the shoulder ends before the obstacle 

(i.e.., the obstacle is off-road). Therefore, a warning system must also pass the “Tests for 

Departures on Roads with Maximum AMR” that appear in section 7. 

These tests evaluate the system's ability to detect an obstacle and to warn when there is a 

potential for a lateral collision. A map may provide information regarding obstacles, but 

this information may be incomplete, inaccurate or unavailable. Thus, a warning system 

must use a real-time sensor (e.g., radar) to detect obstacles. The warning system deals 

with longitudinal barriers and discrete objects. 

A longitudinal barrier appears as one long continuous obstacle, such as a jersey barrier. 

The vehicle drifts slowly toward the barrier much like a lane departure. The warning 

system uses a side-looking sensor to detect these obstacles. 

A discrete object appears on the shoulder ahead of the vehicle. Examples of discrete 

obstacles include parked cars, bridge supports, and the beginning of a longitudinal 

barrier. If the vehicle drifts too far outside the lane, it will collide with the object. After 

a warning, the driver steers away from the obstacle to avoid a collision. The system uses 

a side-forward sensor (i.e., aimed forward and to the side) to detect these obstacles. 

The sensors used by the system must detect a wide range of obstacles with varying 

properties. Small obstacles, such as pedestrians and motorcycles, pose the greater 

challenges. The tests use similar sized obstacles made of safer material to reduce the risk 

of serious damage. 

The tests involve placing the obstacles at two distances (i.e., offsets) from the lane edge. 

The large offset is twice the maximum AMR. The system should detect the large 

obstacle offset but limit the AMR to the maximum in order to provide consistent 

warnings. The small obstacle offset is half the maximum AMR. The system should 

detect the small offset and adjust the warning accordingly. The earlier warning indicates 

the system successfully detected the obstacle. 

The test scenarios include obstacles on a straight road and on a curved road. 
63 

8.1 Barrier on Straight Road 

The Barrier on Straight Road test assesses the warning system’s ability to detect the 

location of a barrier and to adjust the warning location on a straight road departure. 

The figure below illustrates the test scenario. Left-side collision tests position the barrier 

outside of the yellow line. 

Figure 24. Barrier on Straight Road Test, Vehicle Trajectory 

8.1.1 Events and System Response 

The following table defines the events for this test and the correct system response. See 

the figure above to locate the event (e.g., Id A1 is label 1 in figure A). 

Id Event Correct Response 

A1 Lateral collision 1. Issue lateral collision warning 

B1 Lateral collision 1. Same as A1 

8.1.2 Test Conditions 

The conditions for this test include the following. 

8.1.2.1 Road Geometry 

The road geometry for the test is: 
64 

Road Geometry Dimension 

Straight (defined using radius of curvature) > 1000 m 

Appendix A, Methods for Determining Road Dimensions and Geometry, contains the 

recommended method to verify the road geometry. 

8.1.2.2 Available Maneuver Room 

In this test, obstacle offset affects the AMR. However, the test limits the AMR to a 

default maximum value to prevent large variations in warning location due to large 

variations in obstacle offset. 

Available Maneuver Room Comment 

1 m (39 in) Maximum AMR 

8.1.2.3 Speed 

The vehicle speeds during the tests cover the warning system operating range. 

Low Speed Medium Speed High Speed 

64 km/h (40 mph) 89 km/h (55 mph) 113 km/h (70 mph) 

8.1.2.4 Departure rate 

The vehicle departure rates during the tests fall within two ranges. These rates are 

comparable to the rates suggested in the ROR report and in the ISO standard for testing 

lateral drift warning systems. 

Low Departure Rate High Departure Rate 

≤ 0.75 m/s > 0.75 m/s 

8.1.2.5 Barrier 

For safety purposes, this test uses a plastic, water-filled jersey barrier as shown in Figure 

25. 
65 

Figure 25. Water-filled Plastic Jersey Barrier 

8.1.2.6 Barrier Offset 

The tests involve placing the obstacles at two offsets measured from the outside edge of 

the lane marker. The small offset is one half the maximum AMR and the large offset is 

twice the AMR. The system evaluator updates these values if the default minimum or 

maximum AMR changes. 

Barrier Offset Name Dimension 

Small Offset 0.5 m (19.5 in) 

Large Offset 2 m (79 in) 

8.1.3 Measurements 

Measurements collected during the test support the following: 

1. Determine whether a warning was given 

2. Determine the desired location of a warning given the conditions 

3. Determine the amount of time the warning gives driver 

8.1.3.1 Time of Warning 

See section 2.3.9. 

8.1.3.2 Longitudinal Speed 

See section 2.2.2. 

8.1.3.3 Distance to Road Edge 

See section 2.2.7. For this test, the road edge is the base of the barrier. 

8.1.3.4 Lateral Velocity 

See section 2.2.4. 
66 

8.1.4 Test Procedure 

The general procedure for the test repeats a series of road departure trajectories depicted 

in Figure 24. 

8.1.4.1 Pre-Test Procedures 

The procedures before the test are: 

1. Ensure road geometry meets the test condition and measure the geometry if 

unknown (see Appendix A, Methods for Determining Road Dimensions and 

Geometry). 

2. Ensure lane marker characteristics meet the test conditions and measure the 

characteristics if it is unknown (see sections 2.1.1-2.1.12). 

3. Check speedometer accuracy (see section 2.2.2). 

4. Verify IMS camera calibration according to recommendations in [5] and repeat 

camera calibration if camera has moved. 

5. Ensure microphone detects warning system alerts and driver speech. 

6. Ensure recording system is working properly. 

7. Ensure GPS has sufficient satellite signals. 

8. Assemble the barriers at the desired offset (large distance for first test set). 

9. Verify road boundary for test (i.e., outer lane marker plus AMR) and practice 

vehicle trajectories (speeds, departure rate, etc.) until accomplished safely and 

reliably. 

8.1.4.2 Test Procedures 

The procedures during the test are: 

1. Achieve speed. The driver brings the vehicle to the prescribed speed. The driver 

may use cruise control if the vehicle is properly equipped. 

2. Execute departure. The driver steers toward the barrier at the prescribed departure 

rate (high or low) until a warning occurs or the driver decides to avoid the barrier. 

Section 2.2.8 provides a method to achieve the prescribed departure rate. 

3. Record departure rate. The assistant records the estimated departure rate as either 

low or high. 

4. Go to start of next collision trajectory. The driver brings the vehicle back around in 

preparation for the next collision trajectory. 

5. Repeat steps 1-4 for: 

a. Five right-side collisions at the low departure rate. 

b. Five left-side collisions at the low departure rate. 

c. Five right-side collisions at the high departure rate. 

d. Five left-side collisions at the high departure rate. 

6. Repeat steps 1 - 5 for the prescribed middle speed. 

7. Repeat steps 1 - 5 for the prescribed high speed. 

8. Repeat steps 1 - 7 with the barriers at the small offset. 

8.1.4.3 Post-Test Procedures 
67 

The procedures after the test are: 

1. Verify IMS camera orientation has not changed. Repeat tests if changed. 

8.1.5 Evaluation Methods 

Use the following methods to evaluate warning system performance. 

8.1.5.1 Rate System Response 

Examine the video and audio data and rate each warning scenario. 

The rating is a true positive if the system responds with a warning before the road 

boundary is crossed. 

The rating is a false negative if the system does not respond with a warning before 

the road boundary is crossed. 

8.1.5.2 Desired Location of Warning 

For each test run, the evaluator determines the desired location of the warning. The 

desired location varies with the forward speed and curve radii. 

1. Locate the time of warning in the video data (for example, by locating video frame 

where alert is first displayed). 

2. Measure lateral position and lateral velocity to the road edge at time of warning. 

3. Use equation (1) in section 5.1.1 to determine the desired location for a warning on a 

straight road. 

8.1.5.3 Timeliness of Warning 

For each test run, the evaluator determines whether the warning is early, late or on time

using steps described in section 5.1.1. The results of the timeliness evaluations are 

accumulated according to section 5.3. 

8.1.6 Reporting 

The evaluator completes the following tables from the data in each test. 

Name of Test Collision with Barrier on Straight Road 

Date of Test 

Warning System ID Name and Version Number 

Test Run Results 

Factors Results

Offset 

m 

Speed 

mph 

Departure 

Rate m/s 

Direction Signal # of 

runs Run 

# 

CR 

T/F 

vf 

mph

vl 

m/s

ym 

m

yw 

m

T 

OT/E/L 

0.5 40 ≤ 0.75 Left No 5 1 

0.5 " " " " 2... 

0.5 40 ≤ 0.75 Right No 5 
68 

0.5 40 > 0.75 Left No 5 

0.5 40 > 0.75 Right No 5 

0.5 40 > 0.75 Left On 1 

0.5 55 ≤ 0.75 Left No 5 

0.5 55 ≤ 0.75 Right No 5 

0.5 55 > 0.75 Left No 5 

0.5 55 > 0.75 Right No 5 

0.5 55 > 0.75 Left On 1 

0.5 55 > 0.75 Right On 1 

0.5 70 ≤ 0.75 Left No 5 

0.5 70 ≤ 0.75 Right No 5 

0.5 70 > 0.75 Left No 5 

0.5 70 > 0.75 Right No 5 

0.5 70 > 0.75 Left On 1 

0.5 70 > 0.75 Right On 1 

2.0 40 ≤ 0.75 Left No 5 

2.0 40 ≤ 0.75 Right No 5 

2.0 40 > 0.75 Left No 5 

2.0 40 > 0.75 Right No 5 

2.0 40 > 0.75 Left On 1 

2.0 55 ≤ 0.75 Left No 5 

2.0 55 ≤ 0.75 Right No 5 

2.0 55 > 0.75 Left No 5 

2.0 55 > 0.75 Right No 5 

2.0 55 > 0.75 Left On 1 

2.0 55 > 0.75 Right On 1 

2.0 70 ≤ 0.75 Left No 5 

2.0 70 ≤ 0.75 Right No 5 

2.0 70 > 0.75 Left No 5 

2.0 70 > 0.75 Right No 5 

2.0 70 > 0.75 Left On 1 

2.0 70 > 0.75 Right On 1 

Offset = Offset distance (in meters) of barrier from outside edge of lane marker 

CR = System gave correct response (T) or failed to give correct response (F). Refer to 

subsection 1.1 above to determine correct response. 

vf = measured vehicle forward speed 

vl = measured vehicle lateral speed (departure rate) 

ym = measured lateral distance between the vehicle front tire and the road boundary at 

the time of warning 

yw = the desired lateral distance at the time of warning using equation (1) 

T = Timeliness of warning (early, late or on time) 

Test Run Summary Results (see section 5.3) 

Combined Results for 

all runs 

# of 

runs 

# 

CR 

# 

OT 

# 

E 

# 

L 

% 

OT

% 

E 

% 

L 
69 

Date/time of test runs 

False Alarm Incident Report 

Run 

#

Probable Cause 

1 Example: shadows on road misinterpreted as road edge 

... ... 
70 

8.2 Barrier on Curved Road 

The Barrier on Curved Road test assesses the warning system’s ability to detect the 

location of a barrier and to adjust the warning location on a curved road departure. 

The figure below illustrates the test scenario. The left-side collision avoidance test uses a 

right turn curve. 

1

AMR Road

Boundary

A B

Plastic

Barrier

Plastic

Barrier

Guide

Target

Guide

Target

1

AMR Road

Boundary

offset offset

Figure 26. Barrier on Curved Road Test Vehicle Trajectory 

8.2.1 Events and System Response 

The following table defines the events for this test and the correct system response. See 

the figure above to locate the event (e.g., Id A1 is label 1 in figure A). 

Id Event Correct Response 

A1 Lateral collision 1. Issue lateral collision warning 

B1 Lateral collision 1. Same as A1 except earlier 

8.2.2 Test Conditions 

The conditions for this test include the following. 
71 

8.2.2.1 Road Geometry 

The curve radius for this test should be appropriate for the low speed, medium speed and 

high-speed conditions. The following equation calculates the curve radius for each speed 

condition using lateral acceleration limits (alat) from section 2.3.5. 

lat a

v

r

2

=

For the test, the curve radius falls within a range of radii by using the lateral acceleration 

limits for sensitivities 2 and 4. 

Road Geometry Dimension 

Low speed curve, 64 km/h (40 mph) 91 m - 136 m 

Medium speed curve, 89 km/h (55 mph) 172 m - 257 m 

Low speed curve, 113 km/h (70 mph) 278 m - 417 m 

Appendix A, Methods for Determining Road Dimensions and Geometry, contains the 

recommended method to verify the road geometry. 

8.2.2.2 Available Maneuver Room 

In this test, obstacle offset affects the AMR. However, the test limits the AMR to a 

default maximum value to prevent large variations in warning location due to large 

variations in obstacle offset. 

Available Maneuver Room Comment 

1 m (39 in) Maximum AMR 

8.2.2.3 Speed 

The vehicle speeds during the tests cover the warning system operating range. 

Low Speed Medium Speed High Speed 

64 km/h (40 mph) 89 km/h (55 mph) 113 km/h (70 mph) 

8.2.2.4 Barrier 

For safety purposes, this test uses a plastic, water-filled jersey barrier (see Figure 25). 

8.2.2.5 Barrier Offset 

The tests involve placing the obstacles at two offsets measured from the outside edge of 

the lane marker. The small offset is one half the maximum AMR and the large offset is 

twice the AMR. The test operator updates these values if the default minimum or 

maximum AMR changes. 

Barrier Offset Name Dimension 

Small Offset 0.5 m (19.5 in) 

Large Offset 2 m (79 in) 
72 

8.2.3 Measurements 

Measurements collected during the test support the following: 

1. Determine whether a warning was given 

2. Determine the desired location of a warning given the conditions 

3. Determine the amount of time the warning gives driver 

8.2.3.1 Time of Warning 

See section 2.3.9. 

8.2.3.2 Longitudinal Speed 

See section 2.2.2. 

8.2.3.3 Distance to Road Edge 

See section 2.2.7. For this test, the road edge is the base of the barrier. 

8.2.3.4 Distance to Curve Entry Point 

See section 2.2.10. 

8.2.4 Test Procedure 

The general procedure for the test repeats a series of road departure trajectories depicted 

in Figure 26. 

8.2.4.1 Pre-Test Procedures 

The procedures before the test are: 

1. Ensure road geometry meets the test condition. The operator measures the road 

geometry as per Appendix A if required. 

2. Ensure the lane marker characteristics meet the test conditions. The operator 

measures the characteristics if it is unknown (see sections 2.1.1-2.1.12). 

3. Check speedometer accuracy (see section 2.2.2). 

4. Verify IMS camera calibration according to recommendations in [5]. Repeat 

camera calibration if camera has moved. 

5. Ensure microphone detects warning system alerts and driver speech. 

6. Ensure recording system is working properly. 

7. Ensure the GPS has sufficient satellites and operates properly. 

8. Assemble the barriers and position for test (use large offset for first test set). 

9. Verify road boundary for test (i.e., outer lane marker plus AMR) and practice 

vehicle trajectories (speeds, departure rate, etc.) until accomplished safely and 

reliably. 

8.2.4.2 Test Procedures 

The procedures during the test are: 
73 

1. Achieve speed. The driver brings the vehicle to the prescribed speed (low speed 

curve is 64 km/h (40 mph)). The driver may use cruise control if the vehicle is 

properly equipped. 

2. Straighten and center vehicle before entering curve. The driver centers the vehicle 

with the lane markers as a visual guide. The vehicle remains in the center until the 

start of the curve. 

3. Maintain straight trajectory into the curve. As the vehicle enters the curve, the 

driver uses a guide target to maintain a straight trajectory toward the collision. 

4. Collide with obstacle. The driver continues straight until a warning takes place or 

the driver aborts before a collision. 

5. Repeat steps 1-4 for: 

a. Five right-side collisions. 

b. Five left-side collisions. 

6. Repeat steps 1 - 5 for the collision on the middle speed curve. 

7. Repeat steps 1 - 5 for the collision on the high-speed curve. 

8. Repeat steps 1 – 7 with the obstacles at the small offset. 

8.2.4.3 Post-Test Procedures 

The procedures after the test are: 

1. Verify IMS camera orientation has not changed. Repeat tests if changed. 

8.2.5 Evaluation Methods 

Use the following methods to evaluate warning system performance. 

8.2.5.1 Rate System Response 

Examine the video and audio data and rate each warning scenario. 

The rating is a true positive if the system responds with a warning before the road 

boundary is crossed. 

The rating is a false negative if the system does not respond with a warning before 

the road boundary is crossed. 

8.2.5.2 Desired Location of Warning 

For each test run, the evaluator determines the desired location of the warning. The 

desired location varies with the forward speed and curve radii. 

1. Locate the time of warning in the video data (for example, by locating video frame 

where alert is first displayed). 

2. Measure lateral position and lateral velocity to the road edge at time of warning. 

3. Use equation (4) in section 5.1.2 to determine the desired location for a warning on a 

curve. 
74 

8.2.5.3 Timeliness of Warning 

The evaluator determines the timeliness of each warning (early, late or on time) and 

compiles statistics according to section 5.3. 

8.2.6 Reporting 

The evaluator completes the following tables from the data in each test. 

Name of Test Collision with Barrier on Curved Road 

Date of Test 

Warning System ID Name and Version Number 

Test Run Results 

Factors Results

Offset 

m 

Curve Speed 

mph 

Direction # of 

runs Run 

# 

CR 

T/F 

vf 

mph

ym 

m

xw 

m

T 

OT/E/L 

0.075 LS 40 Left 5 1 

" " " " 2... 

0.075 LS 40 Right 5 

0.075 MS 55 Left 5 

0.075 MS 55 Right 5 

0.075 HS 70 Left 5 

0.075 HS 70 Right 5 

2.0 LS 40 Left 5 

2.0 LS 40 Right 5 

2.0 MS 55 Left 5 

2.0 MS 55 Right 5 

2.0 HS 70 Left 5 

2.0 HS 70 Right 5 

Offset = Offset distance (in meters) of barrier from outside edge of lane marker 

Curve = Low speed curve, medium speed curve and high speed curve 

CR = System gave correct response (T) or failed to give correct response (F). Refer to 

subsection 1.1 above to determine correct response. 

vf = vehicle forward speed 

ym = the measured lateral distance between the vehicle front tire and the road boundary 

at the time of warning 

xw = the desired distance to curve entry point at the time of warning using equation (4) 

T = Timeliness of warning (early, late or on time) 

Test Run Summary Results (see section 5.3) 

Combined Results for 

all runs 

# of 

runs 

# 

CR 

# 

OT 

# 

E 

# 

L 

% 

OT

% 

E 

% 

L 

Date/time of test runs 

False Alarm Incident Report 

Run Probable Cause 
75 

#

1 Example: shadows on road misinterpreted as road edge 

... ... 
76 

8.3 Obstacle on Shoulder on Straight Road 

This test assesses the warning system’s ability to detect an obstacle on the shoulder ahead 

of the vehicle and to adjust the warning location on a straight road departure. 

The figure below illustrates the test scenario. Reverse the vehicle’s direction to test a 

left-side collision. 

Figure 27. Obstacle on Shoulder on Straight Road Test, Vehicle Trajectory 

8.3.1 Events and System Response 

The following table defines the events for this test and the correct system response. See 

the figure above to locate the event (e.g., Id A1 is label 1 in figure A). 

Id Event Correct Response 

A1 Lateral collision 1. Issue lateral collision warning 

B1 Lateral collision 1. Same as A1 except earlier 

8.3.2 Test Conditions 

The conditions for this test include the following. 

8.3.2.1 Road Geometry 

The road geometry for the test is: 

Road Geometry Dimension 

Straight (defined using radius of curvature) > 1000 m 
77 

Appendix A, Methods for Determining Road Dimensions and Geometry, contains the 

recommended method to verify the road geometry. 

8.3.2.2 Available Maneuver Room 

In this test, obstacle offset determines the AMR. However, the AMR is limited to a 

maximum value to prevent large variations warning location caused by large variations 

shoulder width. 

Available Maneuver Room Comment 

1 m (39 in) Maximum AMR 

8.3.2.3 Speed 

The vehicle speeds during the tests cover the warning system operating range. 

Low Speed Medium Speed High Speed 

64 km/h (40 mph) 89 km/h (55 mph) 113 km/h (70 mph) 

8.3.2.4 Departure rate 

The vehicle departure rates during the tests fall within two ranges. These rates are 

comparable to the rates suggested in the ROR report and in the ISO standard for testing 

lateral drift warning systems. 

Low Departure Rate High Departure Rate 

≤ 0.75 m/s > 0.75 m/s 

8.3.2.5 Obstacle 

For safety purposes, this test uses a plastic, traffic barrel (see Figure 28). 

Figure 28. Traffic barrel 
78 

8.3.2.6 Obstacle Offset 

The tests involve placing the obstacles at two offsets measured from the outside edge of 

the lane marker. The small offset is one half the maximum AMR and the large offset is 

twice the AMR. The operator updates these values if the default minimum or maximum 

AMR changes.. 

Barrier Offset Name Dimension 

Small Offset 0.5 m (19.5 in) 

Large Offset 2 m (79 in) 

8.3.3 Measurements 

Measurements collected during the test support the following: 

1. Determine whether a warning was given 

2. Determine the desired location of a warning given the conditions 

3. Determine the amount of time the warning gives driver 

8.3.3.1 Time of Warning 

See section 2.3.9. 

8.3.3.2 Longitudinal Speed 

See section 2.2.2. 

8.3.3.3 Distance to Road Edge 

See section 2.2.7. For this test, the base of the obstacle defines the road edge. The 

obstacle will not be adjacent to the front wheel at the time of warning. The evaluator 

calculates the distance to the road edge using the distance to the lane marker plus the 

obstacle offset (see figure below). To take into account the departure angle (θ requires 

departure rate, see section 2.2.9), the evaluator uses the following equation (see Figure 

29): 

cosθ

o

y l h l w = + = +

Where: 

yw = the lateral distance between the vehicle front tire and the road boundary 

l = the measured lateral distance to the lane marker 

o = the known offset of the obstacle 

θ = the departure angle 
79 

yw

Road Edge

Vehicle location

when alert issued

l

Lane 

Marker

Obstacle

O

θ

hθ

Figure 29. Indirect Distance to Road Edge 

8.3.3.4 Lateral Velocity 

See section 2.2.4. 

8.3.4 Test Procedure 

The general procedure for the test repeats a series of road departure trajectories depicted 

in Figure 27. 

8.3.4.1 Pre-Test Procedures 

The procedures before the test consist of the following steps: 

1. Ensure road geometry meets the test condition and measure the geometry if 

unknown (see Appendix A, Methods for Determining Road Dimensions and 

Geometry). 

2. Ensure lane marker characteristics meet the test conditions and measure the 

characteristics if unknown (see sections 2.1.1-2.1.12). 

3. Check speedometer accuracy (see section 2.2.2). 

4. Verify IMS camera calibration according to recommendations in [5]. Repeat 

camera calibration if camera has moved. 

5. Ensure microphone detects warning system alerts and driver speech. 

6. Ensure recording system is working properly. 

7. Ensure GPS has sufficient satellite signals. 

8. Assemble the barrels at the desired offset (large distance for first test set). 

9. Verify road boundary for test (i.e., outer lane marker plus AMR) and practice 

vehicle trajectories (speeds, departure rate, etc.) until accomplished safely and 

reliably. 

8.3.4.2 Test Procedures 

The procedures during the test are: 

1. Achieve speed. The driver brings the vehicle to the prescribed speed. The driver 

may use cruise control if the vehicle is properly equipped. 

2. Execute departure. The driver steers toward the obstacle at the prescribed departure 

rate (high or low) until a warning occurs or the driver decides to avoid the obstacle. 

Section 2.2.8 provides a method to achieve the prescribed departure rate. 
80 

3. Go to start of next collision trajectory. The driver brings the vehicle back around in 

preparation for the next collision trajectory. 

4. Repeat steps 1-3 for: 

a. Five right-side collisions at the low departure rate. 

b. Five left-side collisions at the low departure rate. 

c. Five right-side collisions at the high departure rate. 

d. Five left-side collisions at the high departure rate. 

5. Repeat steps 1 - 4 for the prescribed middle speed. 

6. Repeat steps 1 - 4 for the prescribed high speed. 

7. Repeat steps 1 - 6 with the barriers at the large offset. 

8.3.4.3 Post-Test Procedures 

The procedures after the test are: 

1. Verify IMS camera orientation has not changed. Repeat tests if changed. 

8.3.5 Evaluation Methods 

Use the following methods to evaluate warning system performance. 

8.3.5.1 Rate System Response 

Examine the video and audio data and rate each warning scenario. 

The rating is a true positive if the system responds with a warning before the road 

boundary is crossed. 

The rating is a false negative if the system does not respond with a warning before 

the road boundary is crossed. 

8.3.5.2 Desired Location of Warning 

For each test run, the evaluator determines the desired location of the warning. This will 

vary depending on the measured departure rate and forward speed. 

1. Locate the time of warning in the video data (for example, by locating video frame 

where alert is first displayed). 

2. Measure lateral position and lateral velocity to the road edge at time of warning. 

3. Use equation (1) in section 5.1.1 to determine the desired location for a warning on a 

straight road. 

8.3.5.3 Timeliness of Warning 

For each test run, the evaluator determines whether the warning is early, late or on time

using steps described in section 5.1.1. The results of the timeliness evaluations are 

accumulated according to section 5.3. 

8.3.6 Reporting 

The evaluator completes the following tables from the data in each test. 
81 

Name of Test Collision with Obstacle on Shoulder on Straight Road 

Date of Test 

Warning System ID Name and Version Number 

Test Run Results 

Factors Results

Offset 

m 

Speed 

mph 

Departure 

Rate m/s 

Direction Signal # of 

runs Run 

# 

CR 

T/F 

vf 

mph

vl 

m/s

ym 

m

yw 

m

T 

OT/E/L 

0.5 40 ≤ 0.75 Left No 5 1 

0.5 " " " " 2... 

0.5 40 ≤ 0.75 Right No 5 

0.5 40 > 0.75 Left No 5 

0.5 40 > 0.75 Right No 5 

0.5 40 > 0.75 Left On 1 

0.5 55 ≤ 0.75 Left No 5 

0.5 55 ≤ 0.75 Right No 5 

0.5 55 > 0.75 Left No 5 

0.5 55 > 0.75 Right No 5 

0.5 55 > 0.75 Left On 1 

0.5 55 > 0.75 Right On 1 

0.5 70 ≤ 0.75 Left No 5 

0.5 70 ≤ 0.75 Right No 5 

0.5 70 > 0.75 Left No 5 

0.5 70 > 0.75 Right No 5 

0.5 70 > 0.75 Left On 1 

0.5 70 > 0.75 Right On 1 

2.0 40 ≤ 0.75 Left No 5 

2.0 40 ≤ 0.75 Right No 5 

2.0 40 > 0.75 Left No 5 

2.0 40 > 0.75 Right No 5 

2.0 40 > 0.75 Left On 1 

2.0 55 ≤ 0.75 Left No 5 

2.0 55 ≤ 0.75 Right No 5 

2.0 55 > 0.75 Left No 5 

2.0 55 > 0.75 Right No 5 

2.0 55 > 0.75 Left On 1 

2.0 55 > 0.75 Right On 1 

2.0 70 ≤ 0.75 Left No 5 

2.0 70 ≤ 0.75 Right No 5 

2.0 70 > 0.75 Left No 5 

2.0 70 > 0.75 Right No 5 

2.0 70 > 0.75 Left On 1 

2.0 70 > 0.75 Right On 1 

Offset = Offset distance (in meters) of obstacle from outside edge of lane marker 
82 

CR = System gave correct response (T) or failed to give correct response (F). Refer to 

subsection 1.1 above to determine correct response. 

vf = measured vehicle forward speed 

vl = measured vehicle lateral speed (departure rate) 

ym = measured lateral distance between the vehicle front tire and the road boundary at 

the time of warning 

yw = the desired lateral distance at the time of warning using equation (1) 

T = Timeliness of warning (early, late or on time) 

Test Run Summary Results (see section 5.3) 

Combined Results for 

all runs 

# of 

runs 

# 

CR 

# 

OT 

# 

E 

# 

L 

% 

OT

% 

E 

% 

L 

Date/time of test runs 

False Alarm Incident Report 

Run 

#

Probable Cause 

1 Example: shadows on road misinterpreted as road edge 

... ... 
83 

8.4 Obstacle on Shoulder on Curved Road 

The Obstacle on Shoulder on Curved Road test assesses the warning system’s ability to 

detect an obstacle on the shoulder ahead of the vehicle and to adjust the warning location 

on a curved road departure. 

The figure below illustrates the test scenario. The left-side collision avoidance test uses a 

right turn curve. 

1

AMR

Road

Boundary

A B

O

Corner

Reflector

O

Plastic

Barrier

1

AMR Road

Boundary

Corner

Reflector

Figure 30. Obstacle on Shoulder on Curved Road Test, Vehicle trajectory 

8.4.1 Events and System Response 

The following table defines the events for this test and the correct system response. See 

the figure above to locate the event (e.g., Id A1 is label 1 in figure A). 

Id Event Correct Response 

A1 Lateral collision 1. Issue lateral collision warning 

B1 Lateral collision 1. Same as A1 

8.4.2 Test Conditions 

The conditions for this test include the following. 
84 

8.4.2.1 Road Geometry 

The curve radius for this test should be appropriate for the low speed, medium speed and 

high-speed conditions. The following equation calculates the curve radius for each speed 

condition using lateral acceleration limits (alat) from section 2.3.5. 

lat a

v

r

2

=

For the test, the curve radius falls within a range of radii by using the lateral acceleration 

limits for sensitivities 2 and 4. 

Road Geometry Dimension 

Low speed curve, 64 km/h (40 mph) 91 m - 136 m 

Medium speed curve, 89 km/h (55 mph) 172 m - 257 m 

Low speed curve, 113 km/h (70 mph) 278 m - 417 m 

Appendix A, Methods for Determining Road Dimensions and Geometry, contains the 

recommended method to verify the road geometry. 

8.4.2.2 Maximum Available Maneuver Room 

In this test, obstacle offset determines the AMR. However, the AMR is limited to a 

maximum value to prevent large variations warning location caused by large variations 

shoulder width. 

Available Maneuver Room Comment 

1 m (39 in) Maximum AMR 

8.4.2.3 Speed 

The vehicle speeds during the tests cover the warning system operating range. 

Low Speed Medium Speed High Speed 

64 km/h (40 mph) 89 km/h (55 mph) 113 km/h (70 mph) 

8.4.2.4 Obstacle 

For safety purposes, this test uses a plastic, traffic barrel (see Figure 28). 

8.4.2.5 Obstacle Offset 

The tests involve placing the obstacles at two offsets measured from the outside edge of 

the lane marker. The small offset is one half the maximum AMR and the large offset is 

twice the AMR. The test operator updates these values if the default minimum or 

maximum AMR changes. 

Barrier Offset Name Dimension 

Small Offset 0.5 m (19.5 in) 

Large Offset 2 m (79 in) 
85 

8.4.3 Measurements 

Measurements determine whether a warning was given, the desired location of a warning 

given the conditions and the amount of time the warning gives driver. 

8.4.3.1 Time of Warning 

See section 2.3.9. 

8.4.3.2 Longitudinal Speed 

See section 2.2.2. 

8.4.3.3 Distance to Road Edge 

See section 2.2.7. For this test, the base of the obstacle defines the road edge. If the 

obstacle is not adjacent to the front wheel at the time of warning and a direct 

measurement is not possible, then the evaluator calculates the distance to the road edge 

using the distance to the lane marker plus the obstacle offset (see Figure 29). To take into 

account the departure angle (θ requires departure rate, see section 2.2.9), use the 

following equation: 

cosθ

o

y l h l w = + = +

Where: 

yw = the lateral distance between the vehicle front tire and the road boundary 

l = the measured lateral distance to the lane marker 

o = the known offset of the obstacle 

θ = the departure angle 

8.4.3.4 Distance to Curve Entry Point 

See section 2.2.10. 

8.4.4 Test Procedure 

The general procedure for the test repeats a series of road departure trajectories depicted 

in Figure 30. 

8.4.4.1 Pre-Test Procedures 

The procedures before the test are: 

1. Ensure road geometry meets the test condition. The operator measures the road 

geometry as per Appendix A if required. 

2. Ensure the lane marker characteristics meet the test conditions. The operator 

measures the characteristics if it is unknown (see sections 2.1.1-2.1.12). 

3. Check speedometer accuracy (see section 2.2.2). 

4. Verify IMS camera calibration according to recommendations in [5]. Repeat 

camera calibration if camera has moved. 

5. Ensure microphone detects warning system alerts and driver speech. 

6. Check Ensure recording system is working properly. 
86 

7. Ensure the GPS has sufficient satellites and operates properly. 

8. Assemble the barrels and position for tests (use large offset for first test). 

9. Verify road boundary for test (i.e., outer lane marker plus AMR) and practice 

vehicle trajectories (speeds, departure rate, etc.) until accomplished safely and 

reliably. 

8.4.4.2 Test Procedures 

The procedures during the test are: 

1. Achieve speed. The driver brings the vehicle to the prescribed speed (low speed 

curve is 64 km/h (40 mph)) and sets the cruise control at the speed. 

2. Straighten and center vehicle before entering curve. The driver centers the vehicle 

with the lane markers as a visual guide. The vehicle remains in the center until the 

start of the curve. 

3. Maintain straight trajectory into the curve. As the vehicle enters the curve, the 

driver uses the obstacle as a guide to maintain a straight trajectory toward the 

collision. 

4. Collide with obstacle. The driver continues straight until a warning takes place or 

the driver aborts before collision. 

5. Repeat steps 1-4 for: 

a. Five right-side collisions. 

b. Five left-side collisions. 

6. Repeat steps 1 - 5 for the collision on the middle speed curve. 

7. Repeat steps 1 - 5 for the collision on the high-speed curve. 

8. Repeat steps 1 - 7 with the obstacles at the large offset. 

8.4.4.3 Post-Test Procedures 

The procedures after the test are: 

1. Verify IMS camera orientation has not changed. Repeat tests if changed. 

8.4.5 Evaluation Methods 

Use the following methods to evaluate warning system performance. 

8.4.5.1 Rate System Response 

Examine the video and audio data and rate each warning scenario. 

The rating is a true positive if the system responds with a warning before the road 

boundary is crossed. 

The rating is a false negative if the system does not respond with a warning before the 

road boundary is crossed. 
87 

8.4.5.2 Desired Location of Warning 

For each test run, the evaluator determines the desired location of the warning. The 

desired location varies with the forward speed and curve radii. 

1. Locate the time of warning in the video data (for example, by locating video frame 

where alert is first displayed). 

2. Measure lateral position and lateral velocity to the road edge at time of warning. 

3. Use equation (4) in section 5.1.2 to determine the desired location for a warning on a 

curve. 

8.4.5.3 Timeliness of Warning 

The evaluator determines the timeliness of each warning (early, late or on time) and 

compiles statistics according to section 5.3. 

8.4.6 Reporting 

The evaluator completes the following tables from the data in each test. 

Name of Test Collision with Obstacle on Curved 

Road 

Date of Test 

Warning System ID Name and Version Number 

Test Run Results 

Factors Results

Offset 

m 

Curve Speed 

mph 

Direction # of 

runs Run 

# 

CR 

T/F 

vf 

mph

ym 

m

xw 

m

T 

OT/E/L 

0.075 LS 40 Left 5 1 

" " " " 2... 

0.075 LS 40 Right 5 

0.075 MS 55 Left 5 

0.075 MS 55 Right 5 

0.075 HS 70 Left 5 

0.075 HS 70 Right 5 

2.0 LS 40 Left 5 

2.0 LS 40 Right 5 

2.0 MS 55 Left 5 

2.0 MS 55 Right 5 

2.0 HS 70 Left 5 

2.0 HS 70 Right 5 

Offset = Offset distance (in meters) of obstacle from outside edge of lane marker 

Curve = Low speed curve, medium speed curve and high speed curve 

CR = System gave correct response (T) or failed to give correct response (F). Refer to 

subsection 1.1 above to determine correct response. 

vf = vehicle forward speed 
88 

ym = the measured lateral distance between the vehicle front tire and the road boundary 

at the time of warning 

xw = the desired distance to curve entry point at the time of warning using equation (4) 

T = Timeliness of warning (early, late or on time) 

Test Run Summary Results (see section 5.3) 

Combined Results for 

all runs 

# of 

runs 

# 

CR 

# 

OT 

# 

E 

# 

L 

% 

OT

% 

E 

% 

L 

Date/time of test runs 

False Alarm Incident Report 

Run 

#

Probable Cause 

1 Example: shadows on road misinterpreted as road edge 

... ... 
89 

9 Tests for Departures on Curves at Excessive Speed 

The tests for Departures on Curves at Excessive Speed evaluate the warning system’s 

ability to detect whether the vehicle is traveling too fast for an approaching curve and to 

warn the driver in time to slow the vehicle to a safe speed. Since the curve may be 

beyond visual limits, curve-speed warnings rely on a map to obtain the curvature of 

upcoming road segments and a positioning system (e.g., Global Positioning System) to 

provide the vehicle location relative to the curve. The system estimates the amount of 

deceleration required to slow the vehicle to a safe speed given the distance to the curve. 

The safe speed takes into account the radius of the curve and other available data such as 

temperature and precipitation (e.g., windshield wiper on or off), which provides an 

indirect measure of road friction. The speeds and curve radii are consistent with a rural 

road scenario where this type of crash most often occurs. 

The curve-branch test examines the system's ability to correctly determine whether the 

vehicle is taking the curve or straight branch when a road network splits. Curve-speed 

warnings for the curve-branch of the road are a nuisance when the vehicle is heading 

toward the straight branch of the road. 
90 

9.1 Excessive Speed on Curved Road 

The Excessive Speed on Curved Road test examines the performance of the curve speed 

warning system for the scenario where a vehicle is traveling too fast for an upcoming 

curve in the road. This scenario falls under the "negotiating a curve on undivided nonfreeway with two lanes at non-junction" scenario identified in the NHTSA test scenario 

report as one of the major settings for road departure crashes [3]. This test assumes the 

warning system uses GPS and a digital map to determine the distance to approaching 

curves and the radius of the curve. 

The figure below illustrates the test scenario. 

curve

entry

Room for

Driver to

Recover

d

1

Curve

Entry

Guide

Figure 31. Excessive Speed on Curved Road Test, Vehicle Trajectory 

9.1.1 Events and System Response 

The following table defines the events for this test and the correct warning signal the 

system shall provide. The primary event is the vehicle reaching a distance from a curve 
91 

where the current speed is too fast for the driver to safely negotiate the curve. See the 

figure above to locate the event. 

Id Event Correct Response 

1 Excessive speed for curve 1. Issue excessive speed for curve warning 

9.1.2 Test Conditions 

The conditions for this test include the following. 

9.1.2.1 Road Geometry 

The test examines two types of curves suggested in [3]. A range of curve radii provides 

flexibility in selecting suitable test sites. 

Road Type Dimension 

Non-freeway 50 m – 100 m 

Freeway 200 m – 350 m 

Appendix A, Methods for Determining Road Dimensions and Geometry, contains the 

recommended method to verify the road geometry. 

9.1.2.2 Temperature 

The temperature condition for the test falls within the following ranges: 

Condition Temperature 

Cold 0° C - 3° C (32° F - 38° F) 

Warm 4° C - 7° C (39° F - 45° F) 

Artificial means to achieve the temperature at the sensor are acceptable (e.g., ice). 

9.1.2.3 Precipitation 

The precipitation during the test is either dry or wet. The warning system determines 

precipitation from windshield wiper status. 

Condition Windshield Wiper 

Dry Off 

Wet On 

9.1.2.4 Speed 

The test requires the driver to approach the curve at a speed in excess of the safe speed 

for the curve. Use equation (6) to compute the safe speed for the curve. Use 3 m/s2

 (0.3 

g) lateral acceleration limit (sensitivity = 3) for warm, dry condition. Use 1 m/s2

 (0.1 g) 

for cold, wet condition ([12] page 10.27). The following table provides an example of 

the speeds to use for a test on two radii chosen for freeway and non-freeway roads. 
92 

Road Type Curve 

Radius 

Condition Safe speed Overspeed 1 

(115 %) 

Overspeed 2 

(130 %) 

Warm, dry 87 km/h 

(54 mph) 

100 km/h 

(62 mph) 

113 km/h 

(70 mph) 

Freeway 200 m 

Cold, wet 50 km/h 

(31 mph) 

58 km/h 

(36 mph) 

68 km/h 

(41 mph) 

Warm, dry 53 km/h 

(33 mph) 

61 km/h 

(38 mph) 

33 km/h 

(38 mph) 

NonFreeway 75 m 

Cold, wet 31 km/h 

(19 mph) 

35 km/h 

(22 mph) 

40 km/h 

(25 mph) 

9.1.3 Measurements 

Measurements collected during the test support the following: 

1. Determine whether a warning was given 

2. Determine the desired location of a warning given the conditions 

3. Determine the amount of time the warning gives driver 

9.1.3.1 Time of Warning 

See section 2.3.9. 

9.1.3.2 Longitudinal Speed 

See section 2.2.2. 

9.1.3.3 Distance to Curve Entry Point 

See section 2.2.10. 

9.1.4 Test Procedure 

The general procedure for the test repeats a series of road departure trajectories depicted 

in Figure 31. 

9.1.4.1 Pre-Test Procedures 

The procedures before the test are: 

1. Ensure road geometry meets the test condition and measure the geometry as per 

Appendix A if required. 

2. Ensure the lane marker characteristics meet the test conditions. The operator 

measures the characteristics if it is unknown (see sections 2.1.1-2.1.12). 

3. Check speedometer accuracy (see section 2.2.2). 

4. Verify IMS camera calibration according to recommendations in [5]. Repeat 

camera calibration if camera has moved. 

5. Ensure microphone detects warning system alerts and driver speech. 
93 

6. Ensure recording system is working properly. 

7. Ensure the GPS has sufficient satellites and is operating properly. 

8. Establish proper initial sensor conditions (initial test is a warm, dry, non-freeway 

scenario). 

9. Verify curve entry point for test (i.e., outer lane marker plus AMR) and practice 

vehicle trajectories (speeds, decelerations, etc.) until accomplished safely and 

reliably. Ensure recovery area exists in case driver is not able to keep vehicle in 

lane through curve. 

9.1.4.2 Test Procedures 

The procedures during the test are: 

1. Achieve temperature. Set the system’s temperature sensor too output prescribed 

condition (warm or cold). 

2. Achieve precipitation condition. Set the windshield wiper to the prescribed 

condition (dry = off, wet = on). 

3. Achieve speed. The driver brings the vehicle to the over-speed condition. 

4. Maintain vehicle centered in lane until past curve entry point. Vehicle may depart 

out of lane into recovery area if traveling too fast. 

5. Document the warning type and result. 

6. Repeat steps 1- 5 five times. 

7. Repeat steps 1 – 6 for over-speed 2 (130 % of maximum) 

8. Repeat steps 1 - 7 for cold, wet condition 

9. Repeat steps 1 - 8 for freeway 

9.1.4.3 Post-Test Procedures 

The procedures after the test are: 

1. Verify IMS camera orientation has not changed. Repeat tests if changed. 

9.1.5 Evaluation Methods 

Use the following methods to evaluate warning system performance. 

9.1.5.1 Rate System Response 

Examine the video and audio data and rate each warning scenario. 

The rating is a true positive if the system responds with a warning before the vehicle has 

completed travel through the curve. 

The rating is a false negative if the system does not respond with a warning before the 

vehicle exits the curve. 

9.1.5.2 Desired Location of Warning 

For each test run, the evaluator determines the desired location of the warning. 
94 

1. Locate the time of warning in the video data (for example, by locating video frame 

where alert is first displayed). 

2. Measure distance to curve entry at time of warning. 

3. Use equation (7) in section 5.2 to determine the desired location for a warning when 

traveling too fast for an approaching curve. 

9.1.5.3 Timeliness of Warning 

For each test run, the evaluator determines whether the warning is early, late or on time

using steps described in section 5.2. The results of the timeliness evaluations are 

accumulated according to section 5.3. 

9.1.6 Reporting 

The evaluator completes the following tables from the data in each test. 

Name of Test Curve Speed Warning Test 

Date of Test 

Warning System ID Name and Version Number 

Test Run Results 

Factors Results 

Condition Speed 

mph 

# of 

runs 

Run 

# 

CR 

T/F 

vf 

mph

xm 

m

xw 

m

T 

OT/E/

L 

Warm/Dry 67 10 1 

" " " 2... 

Cold/Wet 52 10 1 

CR = System gave correct response (T) or failed to give correct response (F). Refer to 

subsection 1.1 above to determine correct response. 

vf = measured vehicle forward speed 

xm = The measured distance to the curve at the time of warning 

xw = the desired distance to the curve at the time of warning using equation (7) 

T = Timeliness of warning (early, late or on time) 

Test Run Summary Results (see section 5.3) 

Combined Results for 

all runs 

# of 

runs 

# 

CR 

# 

OT 

# 

E 

# 

L 

% 

OT

% 

E 

% 

L 

Date/time of test runs 

False Alarm Incident Report 

Run 

#

Probable Cause 

1 Example: shadows on road misinterpreted as road edge 

2 Example: longitudinal road joint misinterpreted as road edge 

... ... 
95 

9.2 Curve-Branch Detection 

The Curve-Branch Detection test examines whether the curve-speed warning system 

accurately predicts whether a vehicle is about to travel on a straight or curved branch of a 

road that splits. This test assumes the warning system uses GPS and a digital map to 

determine the distance to approaching curves and the radius of the curve. The scenario 

for this test requires a two-lane road that splits into a straight road and a curved road. 

The curve-branch requires sufficient radius to generate a warning at a reasonable 

approach speed. For test purposes, the rural road curve used in the curve-speed warning 

test may be adapted for the curve-branch test. 

During the curve-branch test, the system issues a warning if the vehicle is in the lane 

headed toward the curve at a high speed (see B in figure below). Conversely, the system 

does not issue a warning if the vehicle is in the lane headed straight (see A in figure 

below). The test verifies correct operation in both lanes. The driver uses the procedure 

in section 9.1 for the test in the curve lane and the procedure below for the straight lane. 

curve

entry

Room for

Driver to

Recover

d

1

Curve

Entry

Guide

Room for

Driver to

Recover

Curve

Entry

Guide

A B

1

Figure 32. Curve-Branch Test, Vehicle trajectory 
96 

9.2.1 Events and System Response 

The following table defines the events for this test and the correct warning signal the 

system shall provide. The primary event is the vehicle reaching a distance from a curve 

where the current speed is too fast for the driver to safely negotiate the curve. See the 

figure above to locate the event. 

Id Event Correct Response 

A1 Reached Curve 1. No warning should be given 

9.2.2 Test Conditions 

The conditions for this test include the following. 

9.2.2.1 Road Geometry 

The road geometry for this test consists of a straight lane adjacent to a curved lane. See 

section 9.1.2.1 for the curved lane radii. It is sufficient to test the freeway curve only. 

The straight lane has the following geometry: 

Road Geometry Dimension 

Straight lane (radius) > 1000 m 

Appendix A, Methods for Determining Road Dimensions and Geometry, contains the 

recommended method to verify the road geometry. 

9.2.2.2 Temperature 

Use same temperature conditions as in section 9.1.2.2. 

9.2.2.3 Precipitation 

Use same precipitation conditions as in section 9.1.2.3. 

9.2.2.4 Speed 

The speeds in the straight lane are the same as those for the curved lane. See section 

9.1.2.4. 

9.2.3 Measurements 

Measurements determine whether a warning was given and whether the test speed was 

within limits. 

9.2.3.1 Time of Warning 

See section 2.3.9. 

9.2.3.2 Longitudinal Speed 

See section 2.2.2. 
97 

9.2.4 Test Procedure 

The general procedure for the test repeats a series of road departure trajectories depicted 

in Figure 32. The driver conducts this test after the curve over-speed test. 

9.2.4.1 Pre-Test Procedures 

The procedures before the test are: 

1. Ensure road geometry meets the test condition and measure the geometry as per 

Appendix A if required. 

2. Ensure the lane marker characteristics meet the test conditions. The operator 

measures the characteristics if it is unknown (see sections 2.1.1-2.1.12). 

3. Check speedometer accuracy (see section 2.2.2). 

4. Verify IMS camera calibration according to recommendations in [5]. Repeat 

camera calibration if camera has moved. 

5. Ensure microphone detects warning system alerts and driver speech. 

6. Ensure recording system is working properly. 

7. Ensure the GPS has sufficient satellites and is operating properly. 

8. Establish proper initial sensor conditions (initial test is a warm, dry, non-freeway 

scenario) 

9.2.4.2 Test Procedures 

The procedures during the test are: 

1. Achieve temperature. Set the system’s temperature sensor to prescribed condition. 

2. Achieve precipitation condition. Set the windshield wiper to the prescribed 

condition (dry = off, wet = on). 

3. Achieve speed. The driver brings the vehicle to the over-speed condition. 

4. Maintain vehicle centered in lane until past the split. 

5. Document the warning type and result. 

a. Repeat steps 1-5 five times. 

6. Repeat steps 1 – 5 for cold, wet condition 

9.2.4.3 Post-Test Procedures 

The procedures after the test are: 

1. Verify IMS camera orientation has not changed. Repeat tests if changed. 

9.2.5 Evaluation Methods 

Use the following methods to evaluate warning system performance. 

9.2.5.1 Rate System Response 

Examine the video and audio data and rate each warning scenario. 

The rating is a false positive if the system responds with a warning while the vehicle 

approaches the split while inside the straight lane markers. 
98 

9.2.6 Reporting 

The evaluator completes the following tables from the data in each test. 

Name of Test Curve Speed Warning Test 

Date of Test 

Warning System ID Name and Version Number 

Test Run Results 

Factors Results 

Condition Speed 

mph 

# of 

runs 

Run 

# 

CR 

T/F 

vf 

mph

Possible causes of false alarm 

Warm/Dry 67 10 1 

" " " 2... 

CR = System gave correct response (T if no warning) or failed to give correct response 

(F if false alarm). 

vf = measured vehicle forward speed 
99 

References

[1] Request for Applications for Cooperative Agreement DTFH61-01-X-00053, A 

Intelligent Vehicle Initiative Road Departure Crash Warning Field Operational Test, 

April 11, 2001, http://www.eps.gov/EPSData/DOT/Synopses/30/DTFH61-01-X00053/DTFH61-01-X-00053.rtf

[2] “Run-Off-Road Collision Avoidance Using IVHS Countermeasures, Final Report”, 

Contract No. DTNH22-93-C-07023, USDOT National Highway Traffic Safety 

Administration, Office of Collision Avoidance Research, December 14 1999. 

[3] Wassim Najm, Jonathan Koopmann, Linda Boyle, Dave Smith, “Development of 

Test Scenarios for Off-Roadway Crash Countermeasures on Crash Statistics”, May 

2001, Report Number DOT-VNTSC-NHTSA-01-02. 

[4] “Standardization Working Draft for PWI14.8 - Lane Departure Warning Systems,” 

International Standards Organization Technical Committee 204, Working Group 14, 

October 23, 2000. This can be obtained from Steven Shladover, 

sess@uclink4.berkeley.edu 

[5] Sandor Szabo, Richard Norcross, “An Independent Measurement System for 

Performance Evaluation of Road Departure Crash Warning Systems,” August 14, 

2005. Can be obtained from Sandor Szabo, sandor.szabo@nist.gov. 

[6] “Vehicle Dynamics Terminology,” SAE J670e, July 1976. 

[7] [4] Deal, F.C., Men, H., Phamdo, N., “Single Vehicle Roadway Departure Prevention 

Program – Public Curve Speed Warning (CSW) and Lateral Drift Warning (LDW) 

Algorithms Design and Performance”, Draft report prepared by Johns Hopkins 

Applied Physics Laboratory, April 2004. 

[8] August Burgett, “DOT's Approach to ITS Safety Evaluations” invited papers to ITS 

America Safety Evaluation Workshop, May 1, 1995. 

[9] August Burgett, Kirsten Gunderson, “Crash Prevention Boundary for Road Departure 

Crashes---Derivation,” Research Note DOT HS 809 399, September 2001. 

[10] Bruce Wilson, August Burgett, “Crash Prevention Boundaries for Road 

Departure,” In Ninth World Congress on Intelligent Transportation Systems, Chicago, 

IL, October 2002. 

[11] A Policy on Geometric Design of Highways and Streets, American Association of 

State Highway and Transportation Officials, 1994. 
100 

[12] R. Lamm, B. Psarianos, T.Mailaender, Highway Design and Traffic Safety 

Engineering Handbook, McGraw-Hill NY, 1999. 

[13] ASTM D 6628 – 01, “Standard Specification for Color of Pavement Marking 

Materials” 

[14] European Standard EN 1436:1997/prA1:2002 “Road marking materials – Road 

Marking Performance for Road Users” 
101 

Appendix A Methods for Determining Road Dimensions and 

Geometry

This section contains recommended methods to verify that road segments satisfy the 

geometry specifications prescribed for the test. 

A.1 Lane Marker Dimensions 

Use a tape measure to verify lane marker dimensions before the test. Alternatively, use 

the IMS to measure lane marker dimensions. 

A.2 Lane Width 

Use a tape measure to verify lane width before the test. Alternatively, use the IMS to 

measure lane width. 

A.3 Curve Radius 

Calculate the curve radius of the road segment over the entire road segment or over the 

portion of the road segmented or at the point of road departure. 

Calculate the curve radius from vehicle speed and a yaw rate sensor (gyro) using the 

following formula (derived from arc length formula): 

θ '

v

r = , 

Where: 

r = radius of curve (m) 

v = vehicle forward speed (m/s) 

θ’ = the yaw rate (radians/s). 

If a GPS is used, calculate the curvature using a three points measured on the curve using 

the Independent Measurement System to visually measure road edge points. 
102 

Appendix B Methods for Determining Lane Marker 

Characteristics

This appendix provides standards for measuring and attaining color and reflectivity 

properties of horizontal pavement markings to ensure that lane markings provide 

appropriate conspicuity for the warning system sensor. The performance of pavement 

markings is determined by the coefficient of retroreflected luminance, RL, the coefficient 

of retroreflected luminance for wet roadways, RL-Wet, the coefficient of retroreflected 

luminance under continuous wetting, RL-Rain, or the luminance coefficient under diffuse 

illumination, Qd. Under the same conditions of headlight illumination and driver’s 

viewing, larger values of these coefficients correspond to higher levels of visual 

performance at corresponding geometry. Reapply the lane markings when they measure 

outside of the specified value. 

The following standard apply for lane-marker reflectance specifications: 

ASTM D 6628 – 01, “Standard Specification for Color of Pavement Marking Materials”, 

ASTM D 6359 – 99, “Standard Specification for Minimum Retroreflectance of Newly 

Applied Pavement Marking Using Portable Hand-Operated Instruments”, 

ASTM E 1710, “Standard Test Method for Measurement of Retroreflective Pavement 

Marking Materials with CEN-prescribed Geometry Using a Portable Retroreflectometer”, 

ASTM E 2177, “Standard Test Method for Measuring the Coefficient of Retroreflected 

Luminance of Pavement Markings in a Standard Condition of Wetness”, 

ASTM Designation E 2176, “Standard Test Method for Measuring the Coefficient of 

Retroreflected Luminance of Pavement Markings in a Standard Condition of Continuous 

Wetting”, and 

European Standard EN 1436:1997/prA1:2002 “Road marking materials – Road Marking 

Performance for Road Users” 

B.1 Terminology 

1. Luminance coefficient under diffuse illumination, Qd – the ratio of the luminance, L, 

of field of the road marking in the given direction by the illuminance , E , on the field, 

expressed in millicandelas per square meter per lux (mcd•m-2•lx-1). 

2. Coefficient of retroreflected luminance, RL – the ratio of the luminance, L, of the field 

of the road marking in the direction of observation by the normal illuminance, E⊥ , 

the field perpendicular to the direction of the incident light, expressed in 

millicandelas per square meter per lux (mcd•m-2•lx-1). 

3. Checkpoint area – the evaluation area within each zone of measurement. 

4. Portable Retroreflectometer – an instrument that can be used in the field or laboratory 

for measuring the coefficient of reflected luminance, RL , and complies with Test 

Method ASTM E 1710. 

5. Condition of wetness – the test condition created by liberally wetting the road 

marking and waiting a certain time period after wetting for the water to run off. 
103 

6. Coefficient of retroreflected luminance on a wet surface, RL-Wet – retroreflectivity of 

horizontal pavement markings in a standard condition of wetness. This condition 

typically exists after a rainfall has ended and the pavement markings are still wet or 

as the markings are still wet from dew or humidity. 

7. Coefficient of retroreflected luminance on a continuously wetted surface, RL-Rain – 

retroreflectivity of horizontal pavement markings in a standard condition of continual 

wetting. This condition typically exists during a rainfall. 

8. Zone of measurement – the road length to measure containing the marking units that 

appear similar in a visual inspection. 

B.2 Measurement Frequency 

The majority of Run-Off-Road sensor validation tests occur in a limited area of a test 

track or roadway. In such limited areas, the test area, the zone of measurement and the 

checkpoint area are equivalent. 

Validate longer zones of measurement (> 300 m) via two checkpoint areas 100 m long 

each and separated by at least 100 m for each kilometer of the test zone. The initial and 

final 100 m of the test zone must be included as check point areas. Carry out the 

necessary remediation and re-verification procedures if a test zone fails to meet the 

required specifications. 

Within each checkpoint area, measure reading sites approximately every 5 m. 

Measurements along Broken Longitudinal Horizontal Pavement Markings shall be the 

same as for continuous markings except there shall be two reading sites per mark and no 

readings between marks. 

B.3 Measurements 

All measurements obtained in the sampling areas are in the direction of traffic flow, i.e., 

in the direction of the vehicle motion during the sensor test. Measure both single and 

double lines to determine compliance with prescribed dimensions and the acceptance 

criteria applied individually to both. 

The measurement geometry used to determine the average coefficient of reflective 

luminance and the luminance coefficient under diffuse illumination shall be 88.76° for 

the entrance angle (β1),(β2=0°) and 1.05° for the observation angle. The aperture angles 

for both the source (if appropriate) and receiver shall not exceed 0.33°. These 

measurement methods specify the use of portable or mobile reflectometers that can 

measure pavement markings in accordance with ASTM Test Method E 1710 or CEN 

1436. The standard measurement condition (see Figure 33) represents the angles 

corresponding to a distance of 30 m for the driver of a passenger car with an eye height of 

1.2 m and a headlight height (if any) of 0.65 m above the road, commonly called the 

“CEN 30 meter geometry”. 
104 

Retroreflective Road marking Stripe

Datum Axis

Surface Normal

1.20 m

0.65 m

 30 m

α

ß = 88.76° = 1.05°

Figure 33. CEN 30 Meter Geometry 

Measurements shall be in accordance with the retroreflectometer manufacturer’s 

specification for operation and calibration. When possible a two-point calibration is 

preferred. The operator shall position the retroreflectometer squarely on or in front of the 

pavement marking material with the illumination in the direction of the sensor test such 

that the illuminated measurement area fits within the width of the road marking. 

Take measurements within 30 days of the Run-Off-Road sensor test when the road is 

clean. If using salt, dirt, or a wetting agent to adjust the luminance of the markings, take 

measurements within 24 hours providing there is no precipitation, high winds, or road 

cleaning in the test zone between the luminance measurements and the Run-Off-Road 

sensor test. 

B.4 Performance Requirement 

The pavement marking material shall be retroreflecting white or yellow, and shall be 

readily visible as white or yellow when viewed from the sensor position with automobile 

headlights at night. Measure the pavement marking after removal of all excess glass 

spheres. Optionally, use light debris, such as dirt or salt, to retard the marking’s 

reflectivity to achieve a value within the desired range. 

The use of the sampling procedure and tables for inspection by attributes (see US Mil-Std 

105D “Sampling Procedure and Tables for Inspection by Attributes”) forms the basis of 

the acceptance criteria. Measurements shall proceed until the decision point for rejection 

is reached, in which case the probability is 95 % that more then 20 % of the pavement 

markings will fall below or more then 20 % of the pavement markings will fall above the 

requirement. If less the acceptance number of readings fall below or above the 

requirements, the probability is 95 % that less then 5 % of the pavement marking will fall 

below or more then 20 % of the pavement markings will fall above the values specified 

and the pavement marking is accepted. 

B.4.1 Dry Day Road Tests 
105 

The method measures the wet retroreflectivity of horizontal pavement markings. 

Measurements shall be taken after a sustained period without precipitation (rain, drizzle, 

or fog) and the roadway and markings appear dry to the touch, and there is no evidence of 

residual wetting. 

Measure the luminance coefficient under diffuse illumination, Qd, in accordance with 

European Standard EN1436: 1997 Annex A. For any set of contiguous 20 readings 

(approximately 100 m), not more then 3 readings may be greater then 130 mcd m-2/lx, 

and not more then 3 readings may be less then 100 mcd m-2/lx for the markings to be 

acceptable for Run Off Road Sensor testing. 

B.4.2 Dry Night Road Tests 

The method measures the wet retroreflectivity of horizontal pavement markings. 

Measurements shall be taken after a sustained period without precipitation (rain, drizzle, 

or fog) and the roadway and markings appear dry to the touch, and there is no evidence of 

residual wetting. 

Measure the coefficient of retroreflected luminance in accordance with ASTM ASTM E 

1710. For any set of contiguous 20 readings (approximately 100 m), not more then 3 

readings may be greater then 130 mcd m-2/lx, and not more then 3 readings may be less 

then 100 mcd m-2/lx for the markings to be acceptable for Run Off Road Sensor testing. 

B.4.3 Wet Road Tests 

This method measures the wet retroreflectivity of horizontal pavement markings in a 

standard condition of wetness. This condition typically exists after a rainfall has ended 

and the pavement markings are still wet or as the markings are still wet from dew or 

humidity. Measurements for tests involving wet roads are similar to methods prescribed 

in ASTM E 2177. “Standard Test Method for Measuring the Coefficient of Retroreflected 

Luminance of Pavement markings in a Standard Condition of Wetness”. 

The operator shall wet the target area with a hand sprayer or bucket. The target area 

includes the marking and the surrounding area. When using a hand sprayer, wet the area 

(the stripe and the road surface) for 30 s. The marking and road surface are to be 

completely flooded. When a hand sprayer is not available, the operator shall slowly pour 

approximately 10 liters of clean water from a bucket over the measurement area (an 

approximately 20 ± 2 in diameter circle). Pour an even crest of water to temporarily 

flood the test surface area. 

Measure the coefficient of retroreflected luminance of the wetted marking 45 ± 5 s after 

completion of the wetting. For any set of 20 readings (approximately 100 m), not more 

then 3 readings may be greater then 50 mcd m-2/lx, and not more then 3 readings may be 

less then 25 mcd m-2/lx for the markings to be acceptable for Run Off Road Sensor 

testing. 

B.4.4 Continuous Wetting Tests 

This method of measuring of the wet retroflective properties of pavement markings 

utilizes a method of continuously wetting the marking during measurement with the 

retroreflectometer and closely follows ASTM E 2176, “Standard Test Method for 

Measuring the Coefficient of Retroreflected luminance of Pavement markings in a 
106 

Standard Condition of Continuous Wetting”. Use the pavement marking’s measured 

performance in conditions of continuous wetting to characterize the performance of the 

marking on the road as water is continuously falling on it. 

10 20 30 40 50

RL

Time (s)

RL-Rain

Steady State 

Area

Figure 34 Definition of RL-Rain

The operator shall position and adjust the water spray with the nozzle such that it 

provides an even spray covering the whole area to be. The spray shall cover an area that 

is 25 % greater then the measuring field measured (generally a 20 ± 2 in diameter circle). 

The variation between the greatest and lowest intensity within the area shall not be 

greater then the ratio 1.7:1. The average spray shall be approximately 20 mm/h (heavy 

rain). 

The operator shall take retroreflectometer readings every 10 s until steady state occurs 

(commonly between 30 s and 60 s). For any set of 20 readings (approximately 100 m), 

not more then 3 readings may be greater then 50 mcd m-2/lx, and not more then 3 

readings may be less then 25 mcd m-2/lx for the markings to be acceptable for Run Off 

Road Sensor testing. 

B.5 Reporting 

The test report shall include: 

1. the date and time, 

2. the location of the test in the form of roadway number, cardinal points, linear distance 

from the cardinal points, traffic direction, and line identification, 

3. the description of the instrumentation and the test method used, 

4. the intended road condition (dry, wet, wetting), 

5. the readings recorded in millicandelas per square meter per lux (mcd•m-2•lx-1).