California Department of Transportation
 

Development and Crash Testing of an Aesthetic,
See-Through Bridge Rail, Type 90

Background

In the early 1990's California crash tested the Type 115 Bridge Rail. It consists of two structural steel rails on structural steel posts that are mounted on the side of the bridge deck. Even though the design could structurally withstand impacts from pickup trucks at 100 km/h, there were some problems with front wheel snagging on the posts during the tests. The railing was consequently downgraded to a TL-1 level as defined in the AASHTO "Guide Specifications for Bridge Railings" (4) and is only recommended for use on narrow, low-volume, low-speed roads.

Type 90 Overview
Type 90

In the late 1990's the Type 80 and Type 80SW were developed to meet the district desires for a see-through concrete bridge rail that could be an alternative to the solid concrete parapet bridge rail, which was the current standard. These bridge rails were designed using the AASHTO "Guide Specifications for Bridge Railings"(4) requirements, but were tested according to NCHRP Report 350. While the Type 80 bridge rails demonstrated their crash-worthiness and their low-maintenance characteristics, concerns developed over the limited see-through characteristics of this rail and its obstruction of scenic views.

Type 115
Type 115
Type 80
Type 80

In an effort to develop more acceptable bridge rail options, the Department has recently conducted an intensive study of aesthetic barriers that have been developed by others.

After looking at all known rail designs that meet NCHRP Report 350 test criteria, several rails were identified that potentially offered improved see-through characteristics, particularly the Wyoming and Alaska rails. Nevertheless, each has its own disadvantages. These include unsuitability for use on a sidewalk, possible maintenance problems, and even some crash performance issues. The conclusion of the Department and the California Coastal Commission is that better aesthetic rail designs need to be developed to meet the needs of local communities in scenic areas.

Development of the Type 90 Bridge Rail

An aesthetic bridge rail, known as the Type 90, was developed by Caltrans' Division of Engineering Services with input from the Division of Design. The final design was then sent to the Division of Research and Innovation's Roadside Safety Research Group for full-scale crash testing. The Type 90 bridge rail consists of a tube steel post and beam system anchored to a reverse-slope concrete curb (see detail and picture below), with 3-m post spacing. The top of the rail is 925 mm above ground level.

Type 90 Detail
Type 90 Detail

Type 90 Bridge Rail Front
Type 90 Bridge Rail Front

Type 90 Back
Type 90 Back
Type 90 Back of Post Close-up
Type 90 Back of Post Close-up

Impact Conditions

Test 631 (NCHRP Report 350 Test 4-11)
Vehicle: 1997 Chevrolet 2500 Ton Standard Cab Pickup
Impact Speed: 100.5 km/h
Impact Angle: 25

Test 632 (NCHRP Report 350 Test 4-10)
Vehicle: 1992 Geo Metro 2-door Hatchback
Impact Speed: 76.5 km/h
Impact Angle: 20
* Re-tested in Test 633 because the impact speed was too slow.

Test 633 (NCHRP Report 350 Test 4-10)
Vehicle: 1994 Geo Metro 4-door Hatchback
Impact Speed: 100 km/h
Impact Angle: 20

Test 634 (NCHRP Report 350 Test 4-12)
Vehicle: 2000 GMC TopKick Van-body Truck
Impact Speed: 80 km/h
Impact Angle: 15

High-speed Crash Test Videos

Test 631 Test 632 Test 633 Test 634
Across Across Across Across
Behind Behind Behind Behind
Upstream Upstream Upstream Upstream
Downstream Downstream Downstream Downstream
Tower Upstream Tower Upstream Tower Upstream Tower Upstream
Tower Downstream Tower Downstream Tower Downstream Tower Downstream
Tower Center Tower Center Tower Center Tower Center

Related Documents and Links

Contact Information

David Whitesel
David.Whitesel@dot.ca.gov
Project Engineer

John Jewell
John.Jewell@dot.ca.gov
Senior Engineer

Bob Meline
Bob.Meline@dot.ca.gov
Senior Engineer