Refer to: HSA-10/WZ-108

Mr. Dave Gertz
TrafFix Devices, Inc.
220 Calle Pintoresco
San Clemente, CA  92672

Dear Mr. Gertz:

Thank you for your letter of January 9, 2002, requesting Federal Highway Administration (FHWA) acceptance of your company's portable sign stands and barricades as crashworthy traffic control devices for use in work zones on the National Highway System (NHS).  Accompanying your letter was a report of the crash testing conducted by Karco Engineering and a video of the tests.  You also asked for our review of the results of tests 1, 2, 3, and 5 that accompanied your July 9, 2001, letter (as you requested at the time we limited our review to the Little Buster stand, the subject of test 4.)  You requested that we find these devices acceptable for use on the NHS under the provisions of National Cooperative Highway Research Program (NCHRP) Report 350 “Recommended Procedures for the Safety Performance Evaluation of Highway Features."

Introduction

The FHWA guidance on crash testing of work zone traffic control devices is contained in two memoranda.  The first, dated July 25, 1997, titled “INFORMATION: Identifying Acceptable Highway Safety Features," established four categories of work zone devices: Category I devices were those lightweight devices which could be self-certified by the vendor, Category II devices were other lightweight devices which needed individual crash testing, Category III devices were barriers and other fixed or massive devices also needing crash testing, and Category IV devices were trailer mounted lighted signs, arrow panels, etc.  The second guidance memorandum was issued on August 28, 1998, and is titled “INFORMATION: Crash Tested Work Zone Traffic Control Devices."  This later memorandum lists devices that are acceptable under Categories I, II, and III.

A brief description of the devices in the two letters follows:

July 9, 2001

Test 1. Sign Stand. Rubber Pole Base with 30 pound ballast, 36 x 36 inch aluminum sign, and light.  The vertical mast of this stand was 2 x 2 inch square 16 gage steel tubing, 66 inches long.  The aluminum signs were supported 18 inches above the ground.

Test 3. Aluminum Buster Sign Stand with 48 x 48 inch aluminum sign bolted to inner mast and Plastic Flag Holder.  The vertical mast of this stand is 1.50 inch square aluminum with 0.100 wall, and 1.25 inch square PVC tubing with 0.250 inch wall.  The 0.080 inch thick aluminum sign weighed 16 pounds and  was mounted at a height of 18 inches above the ground.

Test 4. Little Buster Sign Stand with 1220 x 1220 mm (48 x 48 inch) Aluminum Sign bolted to Full Length Inner Mast and TrafFix Flag holder.  Sign mounted 460 mm (18 inches) above ground.  This device was accepted in FHWA Acceptance Letter WZ-81.

Test 5. Rubber Base Sign Stand with Pinned Inner Mast, 48 x 48 inch aluminum sign and B-Light.  The vertical mast of this stand was 1.75 x 1.75 inch square 16 gage steel tubing, 72 inches long.  The 0.080 inch aluminum signs weighed 16 pounds and was supported 12 inches above the ground.  The Type B warning light weighed 4.5 pounds and was attached to the top of the mast using an Emco plastic flag bracket.

January 9, 2002

Test 1. Little Buster Sign Stand with 48 x 48 inch aluminum sign with Slip-over Tube Mast. The vertical mast outside sleeve of this stand was 1.5 inch square steel 12 gage tube.  The 0.080 inch thick aluminum sign weighed 16 pounds and was mounted at a height of 18 inches above the ground.

Test 2. Type 3 Plastic Barricade with Plastic Posts and Pinned Rubber Bases, carrying a 48 x 48 inch diamond sign.  The vertical posts are extruded PVC plastic, as crash tested by Davidson Plastics and found acceptable in our letter WZ-39.  The extruded plastic rails are High Density Polyethelene, also tested previously.  They were attached to the vertical posts using grade two 1/4 inch bolts.  This barricade carried a lightweight corrugated plastic diamond sign mounted 12 inches above the pavement.  It was attached to the rails with grade two 1/4 inch bolts.

Test 3.  Econo Buster Sign Stand with 48 x 48 inch aluminum sign with Slip-over Outer Tube Mast.  The vertical mast outside sleeve of this stand was 1.5 inch square steel 12 gage tube.   The 0.080 inch thick aluminum sign weighed 16 pounds and  was mounted at a height of 16 inches above the ground.

Test 4. Type III Plastic panel Barricade with Steel Post uprights and Lights, tested with 48 x 48 inch aluminum sign.  The vertical uprights were 1.75 inch square 16 gage steel posts, 72 inches long.  The panels were 96 inches long by 8.5 inches wide and 3/4 inch thick corrugated plastic.  The lights were Empco lights weighing 4.5 pounds mounted on the vertical uprights.

Testing

Full-scale automobile testing was conducted on your company's devices.  Two stand-alone  examples of the device were tested in tandem, one head-on and the next placed six meters downstream turned at 90 degrees, as called for in our guidance memoranda.  The complete device as tested is shown in Enclosure 1.  The crash testing is summarized in the table below:

Windshield damage in Test 1 was primarily due to the flat impact of the warning light.  A small but dense area of cracking was surrounded by more moderated spider web cracking.  A driver should be able to see around the opaque area.

Windshield damage in Test 2 was due to the impact of the sign's mast contacting the roof line. Moderate cracking radiated from this impact point.

Windshield damage in Tests 1 and 3 resulted from the flat impact of the aluminum sign panel in the head-on test.  Cracking was distributed over the whole windshields of both cars but did not significantly impair the driver's ability to see.  Deflection of the glass was between two and three inches.  Therefore, this device will be considered marginally acceptable.

Test 2 was of a plastic framed Type III barricade.  The vertical supports of this barricade shattered upon impact, allowing the horizontal rails to strike the windshield in both the head on and 90 degree tests.  Although there was no windshield penetration in this case, the potential for rigid horizontal panels to spear the vehicle is higher.  It is critical, therefore, that this design use  flexible, lightweight horizontal rails as tested.  The corrugated plastic sign panel mounted on the barricade is acceptable for use as tested.

Windshield damage in Test 4 also resulted from the flat impact of the sign panel mounted to the barricade.  The light gage steel vertical supports crumpled upon impact.  The performance of these vertical supports was better than the plastic supports in Test 2, but did not hold the barricade together as well as the hot-rolled, high carbon steel angles, nor the perforated square steel tubes used in the generic Type III barricade designs distributed by the FHWA in our letter WZ-85.  Even though the results of this test were acceptable, FHWA discourages the use of rigid aluminum or plywood sign panels centered on Type III barricades.  We prefer that lightweight plastic sign substrates be used in this location, such as the sign in Test 2.

Findings

Damage to the windshields of the test vehicles varied as discussed above.  Our assessment of the tested devices is summarized here.

July 9, 2001

January 9, 2001

The results of the testing are compared to the FHWA requirements above.  The devices described above and shown in the enclosed drawings for reference are acceptable as noted for use on the NHS under the range of conditions tested, when proposed by a State.

• Our acceptance is limited to the crashworthiness characteristics of the devices and does not cover their structural features, nor conformity with the Manual on Uniform Traffic Control Devices.
  
  
• Any changes that may adversely influence the crashworthiness of the device will require a new acceptance letter.
  
  
• Should the FHWA discover that the qualification testing was flawed, that in-service performance reveals unacceptable safety problems, or that the device being marketed is significantly different from the version that was crash tested, it reserves the right to modify or revoke its acceptance.
  
  
• You will be expected to supply potential users with sufficient information on design and installation requirements to ensure proper performance.
  
  
• You will be expected to certify to potential users that the hardware furnished has essentially the same chemistry, mechanical properties, and geometry as that submitted for acceptance, and that they will meet the crashworthiness requirements of FHWA and NCHRP Report 350.
  
  
• To prevent misunderstanding by others, this letter of acceptance, designated as number WZ-108 shall not be reproduced except in full.  This letter, and the test documentation upon which this letter is based, is public information.  All such letters and documentation may be reviewed at our office upon request.
  
  
• The may include patented components and if so are considered "proprietary."  The use of proprietary work zone traffic control devices in Federal-aid projects is generally of a temporary nature.  They are selected by the contractor for use as needed and removed upon completion of the project.  Under such conditions they can be presumed to meet requirement "a" given below for the use of proprietary products on Federal-aid projects.  On the other hand, if proprietary devices are specified for use on Federal-aid projects, except exempt, non-NHS projects, they: (a) must be supplied through competitive bidding with equally suitable unpatented items; (b) the highway agency must certify that they are essential for synchronization with existing highway facilities or that no equally suitable alternative exists or; (c) they must be used for research or for a distinctive type of construction on relatively short sections of road for experimental purposes.  Our regulations concerning proprietary products are contained in Title 23, Code of Federal Regulations, Section 635.411, a copy of which is enclosed.

Sincerely yours,

Michael L. Halladay

Acting Program Manager, Safety

Enclosure