B-17

MINUTE. MEMO

Page of Pages

Use this forminlieu oftransmittal slips wirhin Dept. ofTrans. wben

message comment is to be retained as file material. Do not prepare

carbons. Hat to be used in lieu of Form FHWA-121 for informal correspondence.

P- PHWA-Ift

(Rev. 11-67)

u.s. DEPARTMENT OF TRANSPORTATION

FEOERAL. HIGHWAY AOMINISTRATION

SUBJECT

Single Slope Concrete Median Barrier

TO MESSAGE/COMMENT FROM/DATE

Safety Program

Engineers

HEO-01thru 10 IEnclosed are selected portions of a report describing a concrete

barrier developed and tested for the Texas Department of

Highways and Public Transportation.

Its performance is at least equal to the standard concrete

safety shape and its increased height and single-sloped face may

offer some advantages as noted in the report.

Weconsider this median barrier to be innovative in term of

Section 1058 of the ISTEAand it maybe used as such on Federalaid projects if requested by a State Highwayagency.

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2/11/92

Geometric and Roadside Design Acceptance letterB~17

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IEXAS IRANSPORTATION INSTITUTE

DEVELOPMENT OF A SINGLE SLOPE

CONCRETE MEDIAN BARRIER

By

W. Lynn Beason. H. E. Ross. .Jr..

H. S. Perera and Wanda Campise

REPORT NO. 9429C-1

TEXAS TRANSPORTATION INSTITUTE

THE TEXAS A&M UNIVERSITY SYSTEM

COLLEGE STATION. TEXAS

STATE DEPARTMENT OF HIGHWAYS

AND PUBLIC TRANSPORTATION

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I NTRODUCTION

Over the past several years, NewJersey concrete median barriers (CMB)

have gained widespread acceptance. Further, other types of longitudinal

barriers employing the NewJersey shape, including bridge rails and portable

barriers, have become very popular. Full scale crash tests have shown that

New Jersey 1ongi tudi na1 barri ers are capabl e of smoothl y redi rect i ng the

standard vehicle tests specified in NCHRP230 (1) including both the

strength and stability tests.

Whi1e, the use of the NewJersey CMBhas been successful, there are

disadvantages with its use. One of the biggest disadvantages is that the

profile of the NewJersey shape varies with height above grade. This means

that if the roadway is resurfaced, both the height of the barri er and the

shape of the barrier wi11 be substan t i ally changed. It may be that the

performance of the NewJersey safety shape is not negatively affected by

the addition of a few inches of pavement overl aYe However, as the

thickness of the overl ay is increased, the performance of the NewJersey

CMBwill eventua 11y becomeunsatisfactory if, on1y,because of the reduction

of the overall height of the barrier. Therefore, it has become fairly

standard practice to reset the NewJersey longitudinal barriers as the

pavement height is increased in the overlaying process. This process is

both expensive and time consuming. .;".

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The purpose of the research presented in this report was to develop a

new CMBshape whose performance is not impaired by the application of

several inches of pavement overlays. Further, a major effort was made to

develop the geometry of the new CMBso that its effect on impacting

vehicles is as good as or better than the effect of the NewJersey CMB.

The new barrier shape selected consists of a barrier face with a

single slope. This shape was suggested by engineers with the Texas State

Department of Highways and Publ ic Transportation (SDHPT). Because the

1
barrier face has a single, constant slope, its performance is not affected

by overlaying the adjacent pavement. Rather, the additional pavement

overlay serves to anchor the barrier more securely at its base. The

performance of the single slope CMSis controlled by its height and slope.

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The new single slope CMScan be used in either a temporary or a

permanent application. The performance of the new CMSwas documented in a

series of three crash tests. The first test was conducted to verify that

the performance of the barri er is acceptable in a temporary app1icat ion.

The second two tests were accomplished to establish the performance of the

barrier in a permanentapplication as prescribed in NCHRP230 (1).

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The remainder of this report is divided into three major sections.

The next section presents a description of the newly developed single slope

CMS. This is followed by a section on the full scale testing of the single

slope CMS. The final section presents conclusions and recommendations for

the use of the single slope CMS.

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Figure 4. Comparison of Single Slope and New Jersey CMB's.

8
FULL SCALECRASHTESTS

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Three full-scale crash tests were conducted on the single slope CMBto

evaluate its performance with respect to structural adequacy, occupant

risk, and vehicle exit trajectory. The first test involved a 4,500 lb

(2,043 kg) full-size automobile which impacted the single slope CMBin the

temporary configuration. The second and third tests invol ved a 4,500 1b

(2,043 kg) fu 11 -size automobile and a 1,800 1b (817 kg) subcompact

automobile, respectively. The vehicles in the second and third tests

impacted the single slope CMBin the permanent configuration.

The full-scale crash tests were conducted using four 30 ft (9.1 m)

single slope CMB segments connected together to form a 120 ft (36.4 m)

longitudinal barrier. The four 30 ft (9.1 m) barrier segments in the

temporary barrier configuration were positioned on an existing conrete

surface at the TTl test track. These barrier segments were joined with the

angle splice connection without the reinforcing bar grid. The single slope

CMB in the temporary configuration was not attached to the roadway surface

in anyway. This installation represents a typica1 temporary installation.

The four 30 ft (9.1 m) barrier segments in the permanent barrier

configuration were positioned on a specially prepared subbaseconsisting of

2 in (5.1 cm) of type D hot mix asphalt which was placed on top of 4 in

(10.2 cm) of compacted crushed limestone. The subbase was specially

prepared for this project in an area which is immediately adjacent to the

concrete test track. The subbase area was approximately 125 ft (37.9 m)

long and 8 ft (2.4 m) wide as shownin Figure 7. The four barrier segments

were all igned on the subbase such that the impact surface of the barrier

was set back approximately 1 ft (.3 m) from the front of the subbase as

shown in Figure 7. Then, the reinforcing bar grids were put into the slots

at the ends of the barri er segments. Next, another 1 in (2.54 cm) of type

D hot mix asphalt was added to the subbase in front of the barrier and

behind the barrier. This final application of asphalt resulted in a 1 ft

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(.3 m)wide addition of asphalt on the impact side of the barrier and a 5.

ft (1.5 m) wide addition of asphalt on the opposite side of the barrier as

shown in Figure 7. Finally, the barrier slots, the gap between the barrier

segment ends, and the angl e spl ice insets on the ends of the barrier were

all grouted with a mixture of one part sand and two parts cement. The

grout was applied so that the 120 ft (36.4 m) barrier had the appearance of

a continuous barrier. The use of the angle splice connection in the

permanent confi gurat ion is opt i ona1 and it was not used in the permanent

installation described in this report.

...

In all three of the full-scale crash tests, the vehicle impacted the

120 ft (36.4 m) long longitudinal barrier at a point approximately 5 ft

(1.5 m) upstream of the middle barrier segment joint. This impact location

was chosen to provide the most critical impact situation with respect to

both strength and snagging. Test statistics for the three crash tests are

summarized in Table 1. Sequential photographs of the tests are presented

in Appendix B. Accelerometer traces and plots of roll, pitch, and yaw are

presente~ in Appendix C.

Results From Test 9429C-l

In this test, a 1980 Cadillac Sedan DeVille was directed into the

singl e slope CMBdeployed in a temporary configuration. Figures 8 and 9

show the vehicle prior to the impact. The vehicle was propelled into the

barrier using a reverse tow and guidance system. Figure 10 presents the

temporary barrier prior to the impact. The test inertia mass of the

vehicle was 4,500 {2,043 kg}. The height to the lower edge of the vehicle

bumper was 12.5 in {31.8 cm}and it was 21.0 in {53.3 cm}to the top of the

bumper. Other dimensions and information on the test vehicle are presented

in Figure 11. The vehicle was free-wheeling and unrestrained just prior to

the impact.

The speed of the vehicl e at impact was 60.3 mi/h (97.0 km/h) and the

16
17

Table 1. Summaryof crash test results

Test No. 9429C-l 9429C-2 9429C-3

Vehicle Weight, lb (kg) 4500(2043) 1800(817) 4500(2043)

(""

Impact Speed, mi/h (km/hr) 60.3(97.0) 60.7(97.7) 63.1 (101. 5)

Impact Angle, degrees 15.2 19.9 26.5

Exit Angle, degrees 0.5 4.3 8.5

Displacement, in (cm) 7.0(17.8) 0.0(0.0) 0.0(0.0)

Occupant Impact Velocity

ft/s (m/s)

Longitudinal 14.4(4.4) 15.7(4.8) 22.1(6.7) Lateral 17.6(5.4) 27.7(8.4) 28.9(8.8)

Occupant RidedownAcceleration

g's

Longtudi na1 -2.5 -2.3 -4.2

Lateral -7.7 -9.2 -10.7

Vehicle DamageClassification . TAD llLFQ4 11LFQ5 llLFQ5

CDC 11 FLEK2& llLFEW3 11LFAW3

11LFEW3
angle of impact was 15.2 degrees. The vehicle impacted the barrier

approximately 55 ft (16.8 m) from the upstream end of the barrier. The

1eft front wheel of the vehicl e made contact with the barrier at

approximately 0.029 seconds after impact and shortly thereafter the tire

began to ride up the face of the barrier. The vehicle began to redirect at

0.049 seconds. At about 0.160 seconds, the rear of the vehicle struck the

barrier and by 0.173 seconds the vehicle was travell ing parall el to the

barrier at a speed of 51.9 mi/h (83.5 km/h). The vehicl e lost contact with

the barrier at 0.462 seconds travell ing at a velocity of 51.3 mi/h (82.5

km/h) and with an ang1e of 0.5 degrees away from the barri er. The brakes

were then applied and the vehicle yawed in a counter-clockwise direction

and subsequently came to rest 240 ft (73 m) from the point of impact.

Sequential photographs of the impact are shownin Figure 33 in Appendix B.

As shown in Figures 12 and 13, the barrier received only minimal

cosmetic damage. There were tire marks on the face of the barrier to a

maximumheight of 31 in (79 em). The bumper scraped the barrier at a

height of 42 in (107 em). The vehicle was in contact with the barrier for

17 ft (5.2 m). The maximum1at~ra 1 11]0vementof the barri er was 7 in (17.8

em) at the middle joint of the barrier.

The vehicl e sustained moderate damage to the 1eft side as shown in

Figures 14 and 15. Maximumcrush at the left front corner at bumper height

was 12.0 in (30.7 em). The 1eft front rim was bent and the tire damaged.

There was damage to the hood, grill, bumper, left front quarter panel, the

left front and rear doors, the left rear quarter panel and the rear bumper.

As stated previously the impact speed was 60.3 mi/h (97.0 km/h) and

the angl e of impact was 15.2 degrees. The vehicl e lost contact with the

barri er trave 11i ng at 51.3 mi/h (82.5 km/h) and 0.5 degrees. NCHRP230

describes occupant risk evaluation criteria and places limits on these for

acceptable performance for tests conducted with 1,800 lb (817 kg) vehicles

(1). These limits do not apply to tests conducted with 4,500 lb (2,043 kg)

22
vehicles but were computed and reported for information only. The occupant

impact velocity was 14.4 ft/s (4.4 m/s) in the longitudinal direction and

17.6 ft/s (65.4 m/s) in the lateral direction. The highest 0.010 second

occupant ridedown accelerations were -2.5 g (longitudinal) and -7.7 g

(1 ateral). These data and other pertinent information from the test are

summarized in Figure 16.

Vehicular angular displacements are displayed in Figure 36 of Appendix

B. Vehicular accelerations versus time traces filtered at 300 Hz are

presented in Figures 37 through 39 in Appendix C. These data were further

analyzed to obtain the 0.050 second average accel erations. The maximum

0.050 second average accelerations measured near the vehicle center-ofgravity were -3.3 g (longitudinal) and -6.8 g (lateral).

These test results show that the barrier contained and smoothly

redirected the test vehicle with little lateral movementof the barrier.

There was no intrusion into the occupant compartment and minimal

deformation of the occupant compartment. The vehicle remained upright and

relatively stable during the collisioA. The vehicle trajectory at loss of

contact indicates minimumintrusion into the adjacent traffic lanes.

Results From Test 9429C-2

In this test, a 1980 Honda Civic was directed into the single slope

barrier deployed in a permanent configuration using a reverse tow and

guidance system. Figure 17 presents the vehicle prior to the impact.

Figures 18 and 19 showthe single slope CMBin the permanent configuration

prior to the impact. The test inertia mass of the vehicl e was 1,800 1b

(817 kg). The height to the lower edge of the vehicl e bumper was 13.5 in

(34.3 cm) and it was 18.5 in (47.0 cm) to the top of the bumper. Other

dimensions and information on the test vehicle are given in Figure 20. The

vehicle was free wheeling and unrestrained just prior to impact.

27
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TestNo.. . . . . . . 9429C-l

Date. . . . . . . . . 11/22/88

Test Installation. . Single Slope Concrete Barrier

Installation Length. . 120 ft (36.6 m)

Vehicle. . . . . . . 1980 Cadillac

Sedan DeVi11e

Vehicle Weight

Test Inertia. . . . 4,500 lb (2,043 kg)

Vehicle DamageClassification

TAD. . . . . . . . l1LFQ4 CDC . . . . . . . . I1FLEK2&l1LFEW3

MaximumVehicle Crush. 12.0 in (30.5 cm)

Max. Barrier Movement. 7.0 in (17~8 cm)

Figure 16. Summaryof results for test 9429C-l.

Impact Speed. . . 60.3 mi/h (97.0 km/h)

Impact Angle. . . 15.2 deg Exit Speed. . . . 51.3 (82.5 km/h) Exit Trajectory. 0.5 deg Vehicle Accelerations

(Max. 0.050-sec Avg) Longitudinal. . -3.3 g Lateral. . . . -6.8 g OccupantImpactVelocity Longitudinal. . 14.4 ft/s (4.4 m/s~

Lateral. . . . 17.6 ft/s (5.4 m/s)

OccupantRidedownAccelerations

Longitudinal. . -2.5 g Lateral. . . . -7.7 g
The speed of the vehicl e at impact was 60.7 mi/h (97.7 km/h) and the

angl e of impact was 19.9 degrees. The vehicl e impacted the barrier

approximately 55 ft (16.7 m) from the upstream end of the barrier. The

left front wheel made contact with the barrier at approximately 0.016

seconds after impact and shortly thereafter the tire began to be pushed up

the face of the barrier. The vehicl e began to redirect at 0.034 seconds

and at 0.076 seconds the left front tire aired out. By 0.129 seconds, the

vehicle was travelling parallel with the barrier and at about 0.134 seconds

the rear of the vehicle struck the barrier. The vehicle lost contact with

the barrier at 0.273 seconds travell ing at 52.1 mi/h (83.8 km/h) and 4.3

degrees away from the barrier. The brakes were then applied and the

vehi cl e subsequent 1y came to rest 160 ft (49 m) from the poi nt of impact.

Sequential photographs of this test are shownin Figure 34 of Appendix B.

As shown in Figure 21, the barrier received minimal cosmetic damage.

There were tire marks on the face of the barrier to a maximumheight of 24

in (61 cm). The bumper scraped the barrier at a height of 30 in (776 cm)

and there were sheet metal scrapings at 35 in (89 cm). The vehicle was in

contact with the barrier .for 9.5 ft (2.9 m). There was no discernable

movementof the barrier.

The vehicle sustained moderate damage to the left side as shown in

Figure 22. Maximumcrush at the left front corner at bumper height was 7.0

in (17.8 cm). The left front and rear struts were damaged, the left front

rim was bent, and the tire was damaged. There was damage to the hood,

grill, front bumper, left front quarter panel, the left door, the left rear

quarter panel and the rear bumper.

As stated previously, the impact speed was 60.7 mi/h (97.7 km/h) and

the angle of impact was 19.9 degrees. The vehicle lost contact with the

barri er tra ve 11 i ng at 52.1 mi/h (83.8 km/ h) and with an ang1e of 4.3

degrees with the barrier. NCHRP230 describes occupant risk eval uation

cri teria and places 1imits on these for acceptable performance for tests

33
i

conducted with 1,800 lb (817 kg) vehicles impacting longitudinal barriers

with a speeds of 60 mph (96 km/h) and angles of 15 degrees (1). These

limits do not apply to this particular test because the impact angle was 20

degrees. However, these limits were computed and reported for information

purposes only. The occupant impact velocity was 15.7 ft/s (4.8 m/s) in the

longitudinal direction and 27.7 ft/s (8.4 m/s) in the lateral direction.

The highest 0.010 second occupant ridedown accelerations were -2.3 g

(longitudinal) and -9.2 g (lateral). These data and other pertinent

information from the test are summarized in Figure 23.

Vehicle angular displacements are displayed in Figure 40 in Appendix

B. Vehicular accelerations versus time traces filtered at 300 Hz are

presented in Figures 41 through 43 in Appendix B. These data were further

analyzed to obtain 0.050 second average accelerations versus time. The

maximum0.050 second averages measured at the center-of-gravity were -6.5 g

(longitudinal) and -15.3 g (lateral).

The barrier contained and smoothly redirected the test vehicle with no

1ateral movement of the barri,er. There was minimal intrusion into the

occupant compartment and minimal deformation of the compartment. The

vehicle remained upright and relatively stable during the collision. The

vehicle trajectory at the loss of contact indicates minimumintrusion into

adjacent traffic lanes with the change in velocity being within recommended

NCHRPlimits for a 15 degree impact. The longitudinal occupant/compartment

impact velocity waswithin the limit recommendedin NCHRP230 for 15 degree

impacts. The 1ateral impact velocity exceeded the reconunendedNCHRP230

limit for 15 degree impacts. However, the lateral impact velocity was less

than the limiting value presented in NCHRP230 and is consistent with the

performance of other vehicles impacting rigid barriers under similar

conditions (6,7). It should also be noted that new impact performance

standards are currently being considered to replace the current NCHRP230

criteria (8). Finally, comparisons of the current tests with similar tests

conducted on NewJersey barriers show that the vehicle redirection with the

36
0.000 s 0.073 s

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0.146 s 0.248 s

W I

Impact Speed. . . 60.7 mi/h (97.7 km/h)

Impact Angle. . . 19.9 deg

Exit Speed. . . . 52.1 (83.8 km/h)

Exit Trajectory. 4.3 deg Vehicle Accelerations

(Max. 0.050-sec Avg)

Longitudinal. . -6.5 9

Lateral. . . . -15.3 g Occupant Impact Velocity

Longitudinal. . 15.7 ft/s (4.8 m/s)

Lateral. . . . 27.7 ft/s (8.4 m/s) Occupant RidedownAccelerations

Longitudinal. . -2.3 9

Lateral. . . . -9.2 9

Summaryof results for test 9429C-2.

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Test No. . . . . . . . 9429C-2

Date. . . . . . . . . 12/05/88

Test Installation. . Single Slope Concrete Barrier

Installation Length. . 120 ft (36.6 m) Vehicle. . . . . . . 1980Honda

Civic

Vehicle Weight

Test Inertia. . . . 1,800 lb (817 kg)

Vehicle Damage Classification

TAD. . . . . . . . l1LFQ5 CDC . . . . . . . . l1LFEW3

MaximumVehicle Crush. 7.0 in (17.8 cm)

Figure 23..
- -- - - - -- - - - __un

new single slope barier is more stable than similar impacts with the New

Jersey shape barri ers.

Results From Test 9429C-3

This test invol ved the impact of a 1979 Caddi 1ac Sedan deVi 11 e as

shown in Figure 24. The vehicle was directed into the barrier using a

reverse tow and guidance system. Figure 25 presents the single slope

barrier prior to the impact. The barrier shown in Figure 25 is the same

barrier used in the previous test with paint added for cosmetic purposes.

The test inertia mass of the vehicle was 4,500 lb (2,043 kg). The height

to the lower edge of the vehicl e bumper was 12.0 in (30.5 cm) and it was

23.0 in (58.4 cm) to the top of the bumper. Other dimensions and

information on the test vehicle are presented in Figure 26. The vehicle

was free-wheeling and unrestrained just prior to impact.

The speed of the vehicl e at impact was 63.1 mi/h (101.5 km/h) and the

an-gle of impact was 26.5 degrees. The vehicl e impacted the barrier

approximately 54 ft (16.5 m) from the upstream'end of the barrier. The

left front wheel made contact with the barrier at approximately 0.024

seconds after impact and shortly thereafter the tire began to be pushed up

the face of the barrier. The vehicle began to redirect at 0.034 seconds

and at about 0.171 seconds the rear of the vehicle struck the barrier. The

left side of the vehicle became airborne at 0.188 seconds. By 0.198

seconds the vehicle was travelling parallel with the barrier at a speed of

53.2 mi/h (85.6 km/h). The vehicle became completely airborne at 0.295

seconds. While still airborne, the vehicle lost contact with the barrier

at 0.360 seconds travell ing at 51.8 mi/h (83.3 km/h) and 8.5 degrees away

from the barrier. The right front tire touched ground at 0.726 seconds

after impact. The brakes were then applied and the vehicle subsequently

came to rest 165 ft (50 m) from the point of impact. Sequential

photographs of this test are presented in Figure 35 in Appendix B.

38
As shownin Figure 27, the barrier received minimal cosmetic damage.

There were tire marks on the face of the barrier to a maximumheight of 34

in (86 em). The bumper scraped the barrier at a height of 40 in (102 ern)

and there were sheet metal scrapings to the top of the barrier.

Examinations of the high speed movies and direct measurements of the

markings on the barrier showthat center of the automobile wheel hub rose

to a height of 26-30 in (66-76 em) before losing contact with the barrier.

The vehicle was in contact with the barrier for 13 ft (4 m). There was no

discernable movementof the barrier.

The vehicle sustained severe damage to the left side as shown in

Figures 28 and 29. Maximumcrush at the left front corner at bumperheight

was 12.0 in (30.5 ern). The floorpan and subframe were bent and the left

side of the rear axle was damaged. The left front rim was bent and the

tire was damaged. There was damageto the hood, gri 11, radi ator and fan,

front bumper, left front quarter panel, the left front and rear doors, the

left rear quarter panel, and the rear bumper. The right front quarter

panel was bent whenthe front of the vehicle shifted to the right about 5

in (13 cm).

As stated previously, the impact speed.was 63.1 mi/h (101.5 km/h) and

the angle of impact was 26.5 degrees. The vehicle lost contact with the

barrier travell ing at 51.8 mi/h (83.3 km/h) and 8.5 degrees. NCHRP230

describes occupant risk criteria and places limits on these for acceptable

performance for tests involving 1,800 lb (817 kg) impacting at 15 degrees

with a velocity of 60 mph (96 km/h) (I). These limits do not apply to

tests conducted at 25 degree impact angles but were computedand reported

for information only. Occupant impact velocity was 22.1 ft/s (6.7 m/s) in

the 10ngi t udin a1 dire ct ion and 28.9 ft Is (8.8 mls) i nth e 1ate r a1

direction. The highest 0.010 second occupant ridedown accelerations were - 4.2 g (longitudinal) and -10.7 g (lateral). These data and other pertinent

information from the test are summarizedin Figure 30.

42
0.120

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9429C-3

. 12/12/88 . Single Slope Concrete Barrier

Installation Length.. 120 ft (36.6 m) Vehicle. . . . . . . 1979Cadillac

SedandeVille

TestNo...... Date . . . . . . .

. Test Installation

Vehicle Weight Test Inertia.

... 4,500lb (2,043kg)

Vehicle DamageClassification TAD. . . . . . . . 11LFQ5 CDC. . . . . . . . l1LFAW3

MaximumVehicle Crush. 12.0 in (30.5 cm)

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ImpactSpeed... 63.1 mi/h (101.5 km/h) ImpactAngle. . . 26.5 deg Exit Speed.. . . 51.8 (83.3 km/h) Exit Trajectory. 8.5 deg

Vehicle Accelerations

(Max. 0.050-sec Avg)

Longitudinal.. -6.4g

Lateral.... -13.1g

Occupant Impact Velocity

Longitudinal. .22.1 ft/s (6.7 m/s) Lateral. . . . 28.9 ft/s (8.8 m/s)

Occupant Ridedown Accelerations

Longitudinal.. -4.2g Lateral. . . . -10.7g

Figure 300 Summaryof resul ts .for test 9429C-3.

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II) (1)

" c...

0 -S

(1) (1) II) 3 -S C" "0 s::: II) (1) .....

AI ..... (1) (1) II) -S " ::s " " '< 3 ..... " ..... s::: n ::s 0 ("") (') :::T

s::: ::s 3: :::T AI ""' ..... 0:1 " AI (1) " 3 -S ;£ :::T - 0 " ..... (1) ..... en -S :::T

'< -S II)

-. (1)(1)
true with nontracking, high angle, low velocity impacts of small vehicles.

A total of three full-scale tests were conducted on the new single

slope CMB. The first test involved a 4,500 lb (2043 kg) impacting the new

barrier in a temporary configuration. The second and third tests involved

an 1,800 1b (817 kg) automobile and a 4,500 1b (2043 kg) automobi 1e. In

all cases the vehicles were smoothly redirected with no snagging. Results

from these tests were within acceptable limits for roll, pitch, yaw,

acceleration as described in NCHRP230 (1). As such the new single slope

CMBis recommendedfor immediate use.

!

..

49