April 30, 2002 

 Refer to: HSA-10/B99 

Larry F. Sutherland 

Deputy Director, Office of Roadway Engineering Services 

Ohio Department of Transportation 

P.O. Box 899 

Columbus, Ohio 43216-0899 

Dear Mr. Sutherland: 

In your April 3 letter, you requested the Federal Highway Administration’s (FHWA) 

acceptance of the Ohio Department of Transportation’s Thrie-beam transition to a 

vertical concrete parapet as a National Cooperative Highway Research Program 

(NCHRP) Report 350 transition design at test level 4 (TL-4). Mr. Powers independently 

received copies of the Texas Transportation Institute (TTI) test reports dated August 

2001, entitled “NCHRP Report 350 Test 3-21 on the Ohio Type 1 Transition from Thrie 

Beam to Concrete Parapet with Asphalt Curb” and February 2002, entitled “NCHRP 

Report 350 Test 4-22 on the Ohio Type 1 Transition from Thrie Beam to Concrete 

Parapet with Asphalt Curb” and videotapes of the two tests that were conducted. 

The tested transition design consists of 3810 mm of nested Thrie-beam rail bolted to a 

vertical-faced concrete parapet at the bridge end and connected to standard w-beam 

barrier with a 12-gauge symmetric w-beam to Thrie-beam transition piece on the 

approach end. The first post was approximately 1.26 m from the parapet and the second 

post 952.5 mm from the first. Both posts were 2440-mm long W200 x 35.9 steel posts. 

The next three posts were also on 952.5-mm centers, with post no. 3 being a 2440-mm 

long W150 x 37 and post nos. 4 and 5 being the same size, but only 1830-mm long. Post 

no. 6 was the same size and length as posts 4 and 5, but with a 1905-mm spacing. All 

remaining posts were standard strong posts on 1905-mm centers. All posts used routed 

wood offset blocks. A 7.1-m long, 100-mm high and 152-mm wide asphalt curb was 

installed with its traffic face 25 mm in front of the Thrie-beam. Enclosure 1 shows these 

and other design details. 

Tests 3-21 (pickup truck) and 4-22 (single unit truck) were conducted on the Ohio 

transition design and the summary results are shown in Enclosure 2. All evaluation 

criteria were met, although the passenger compartment intrusion in the pickup truck was 

judged to be marginal. I am aware that the same test, but without the asphalt curb, 

resulted in unacceptable passenger compartment intrusion. Thus the 100-mm high curb 

is an essential design element. This curb can be made of asphalt, as tested, or it may be a 

concrete curb. You may wish to specify a curb higher than 100 mm to reduce wheel 

snagging on the concrete parapet and enhance overall crash performance. You should 

also consider specifying a 10-gauge w-beam to Thrie-beam transition piece in your 
design. Tests by other agencies have shown that a 12-gauge piece is not stiff enough 

when connected directly to nested Thrie-beam and can tear when struck at that location. 

Based on the reported test results, and subject to your consideration of the above 

recommendations, I conclude that your Thrie-beam transition design satisfies the 

evaluation criteria for an NCHRP Report 350 test level 4 (TL-4) transition and may be 

used on the National Highway System. 

 Sincerely yours, 

 

 (original signed by A. George Ostensen) 

A. George Ostensen 

 Program Manager, Safety 

2 Enclosures 

0.000 s 0.148 s 0.247 s 0.370 s

General Information

Test Agency .............

Test No. ................

Date ...................

Test Article

Type ..................

Name ..................

Installation Length (m) .....

Material or Key Elements ...

Soil Type and Condition .....

Test Vehicle

Type ..................

Designation .............

Model .................

Mass (kg)

Curb .................

Test Inertial ...........

Dummy ..............

Gross Static ...........

Texas Transportation Institute

401021-5

07/03/01

Transition

Ohio Type 1 Transition

33.7

Nested Thrie Beam Transition

to Concrete Parapet with Asphalt Curb

Standard Soil, Dry

Production

2000P

1996 Chevrolet 2500 pickup truck

1897

2000

 76

2076

Impact Conditions

Speed (km/h) ................

Angle (deg) .................

Exit Conditions

Speed (km/h) ................

Angle (deg) .................

Occupant Risk Values

Impact Velocity (m/s)

x-direction ................

y-direction ................

THIV (km/h) .................

Ridedown Accelerations (g's)

x-direction ................

y-direction ................

PHD (g’s) ...................

ASI .......................

Max. 0.050-s Average (g's)

x-direction ................

y-direction ................

z-direction ................

100.4

25.8

72.4

16.0

 6.2

 8.9

38.6

-14.5

 11.0

 14.9

 1.95

 -9.9

15.2

 6.7

Test Article Deflections (m)

Dynamic .................

Permanent ...............

Working Width ............

Vehicle Damage

Exterior

VDS ..................

CDC ..................

Maximum Exterior

Vehicle Crush (mm) ......

Interior

OCDI .................

Max. Occ. Compart.

Deformation (mm) .......

Post-Impact Behavior

(during 1.0 s after impact)

Max. Yaw Angle (deg) ......

Max. Pitch Angle (deg) .....

Max. Roll Angle (deg) ......

0.25

0.55

0.47

11LFQ3

11FLEK2

&11LYEW2

570

FS0214100

120

 83

-16

-20

Summary of results for test 401021-5, NCHRP Report 350 test 3-21.
0.000 s 0.242 s 0.726 s 1.935 s

General Information

Test Agency .............

Test No. ................

Date ...................

Test Article

Type ..................

Name ..................

Installation Length (m) .....

Material or Key Elements ...

Soil Type and Condition .....

Test Vehicle

Type ..................

Designation .............

Model .................

Mass (kg)

Curb .................

Test Inertial ...........

Dummy ..............

Gross Static ...........

Texas Transportation Institute

401021-2a

01/16/02

Transition

Ohio Thrie Beam Transition

9.95

Thrie Beam Guardrail Attached to

Concrete Parapet with Asphalt Curb

Standard Soil, Dry

Production

8000S

1984 Chevrolet C70 Box Van

5245

8000

 N/A

8000

Impact Conditions

Speed (km/h) ................

Angle (deg) .................

Exit Conditions

Speed (km/h) ................

Angle (deg) .................

Occupant Risk Values

Impact Velocity (m/s)

x-direction ................

y-direction ................

THIV (km/h) .................

Ridedown Accelerations (g's)

x-direction ................

y-direction ................

PHD (g’s) ...................

ASI .......................

Max. 0.050-s Average (g's)

x-direction ................

y-direction ................

z-direction ................

80.2

14.6

69.4

 6.3

 2.7

 4.1

17.8

-5.3

 8.1

 8.7

 0.44

-2.0

 3.7

 2.6

Test Article Deflections (m)

Dynamic ................

Permanent ..............

Working Width ...........

Vehicle Damage

Exterior

VDS .................

CDC .................

Maximum Exterior

Vehicle Crush (mm) .....

Interior

OCDI ................

Max. Occ. Compart.

Deformation (mm) ......

Post-Impact Behavior

(during 1.0 s after impact)

Max. Yaw Angle (deg) .....

Max. Pitch Angle (deg) ....

Max. Roll Angle (deg) .....

0.07

0.18

1.90

11FL1

11FLEW1

270

LF0000000

None

-29.6

 -7.2

 21.1

Summary of results for test 401021-2a, NCHRP Report 350 test 4-22.