March 4, 2005

Refer to: HSA-10/WZ-100 Amendment Six

Mr. William M. Korman, Jr.
Korman Signs, Inc.
3029 Lincoln Avenue
Richmond, Virginia 23228

Dear Mr. Korman:

Thank you for your letter of November 18, 2004, requesting Federal Highway Administration (FHWA) acceptance of a number of your company's portable sign stands and Type III barricades as crashworthy traffic control devices for use in work zones on the National Highway System (NHS). Accompanying your letter were reports of crash testing you conducted and which were witnessed by AnteRapture Engineering. Video of the tests was submitted with your request dated October 5, 2004, which resulted in acceptance letter WZ-100 Amendment #5. Your current request is 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 are those lightweight devices which are to be self-certified by the vendor, Category II devices are other lightweight devices which need individual crash testing but with reduced instrumentation, Category III devices are barriers and other fixed or heavy devices also needing crash testing with normal instrumentation, and Category IV devices are trailer mounted lighted signs, arrow panels, etc. for which crash testing requirements have not yet been established. 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.

Your present request is for several new Model WBT3, Type III barricades with optional attached lights and signs. Based on the results of the recent tests, you asked to amend WZ-100 to add additional features to the NCHRP 350 accepted models by the original WZ-100 and the previous amendments. Also, you requested acceptance of a new method of mounting ALPOLIC® 350 signs on existing Model SS548E, SS548AE, SS548CE, SS548CAE, SS548ETL, SS548AETL, SS560, SS560A, SS560E and SS560AE sign stands.

Description of Devices

All steel used for the Type III barricade crash test articles was ASTM A500, 45,000 psi yield/48,000 psi tensile typical, Grade 1008 with maximum of 0.10% carbon, 0.50% Manganese, 0.030% Phosphorus and .035% Sulfur.

Based upon previous tests and approvals you expect similar results and requested approval for steel up to a nominal 60,000 psi yield in the as-formed cold worked, welded and galvanized condition.

The first series of requests concerns the acceptance of Model WBT3 Type III barricades that are as follows:

  1. 4' to 12' wide and 5' or 7' tall with 8" to 12" tall panels of hollow fluted plastic (polyethylene or polypropylene) of 10mm or 13mm thickness, and hollow extruded plastic (polyethylene, polypropylene or polyolefin) of 1" or 2" nominal thickness or, 2mm thick ALPOLIC® 350 aluminum composite laminate (see drawings). They may be used with or without ballast or staking. They may be used with or without up to two lights of up to 4.4 pounds attached to the top of the upright posts. These barricades may be used with or without up to 33' square of ALPOLIC® 350 signs fastened directly to the panels with a minimum height of 12" to the bottom of the sign.
  2. As above with horizontal legs and vertical upright posts of 1 3/4" to 2" perforated square steel tubing (PSST) with 12 or 14 gauge wall thickness and one or two horizontal cross braces of 1 1/4" to 1 ½" non-perforated 12 to 16 gauge square steel tubing or 1 ¾" to 2" PSST with 12 to 16 gauge wall thickness. The steel cross braces shall be fastened to the upright posts at a level no higher than 27" from the bottom of the legs to the bottom of the top cross brace. The legs, uprights and cross braces may be joined by splice plate brackets, hinge plate brackets, hinge or stub tees, or welded stubs as previously approved.
  3. As above with a range of hinge plate joining brackets for the horizontal legs or the horizontal cross braces from 2" to 4" wide and of steel from 10 gauge to 6 gauge.
  4. As above with optional telescopic legs such that the inner legs as small 1 ¼" square 16 gauge up to 1 ¾" 12 gauge steel tubing (see drawing).
  5. As above with 4" long and at least 1 ¼" square 12 to 16 gauge steel tubes to adapt the lights to the top of the barricade post.
  6. As above with internal stub leg of 60" x 1 ½" square 12 to 16 gauge steel tubing and 4" minimum length stub of the same to fit inside of the 1 ¾" square steel upright. The stub may be attached by welding or by approved brackets.
  7. As above except without the use of warning lights in which case 1-1/2" to 2" square 16 gauge steel tubing may be used for vertical upright posts.

The last request has to do with a modification to ALPOLIC® 350 signs (refer to enclosure 9):

  1. Attaching a lightweight bracket to the signs so that they may be mounted in the same way as a roll-up signs as accepted in WZ-100 and Amendments 2 and 3 for the Models

SS548E, SS548AE, SS548CE, SS548CAE, SS548ETL and SS548AETL stands at the mounting height of 60" and the Models SS560, SS560A, SS560E and SS560AE stands at the mounting height of 84".

The results of the informal crash testing witnessed by AnteRapture Engineering on September 21, 2004, with 5' x 12' barricades constructed of 1 ½" square 16 gauge steel tubing showed that the cross brace at 51" was not crashworthy as it broke out the right rear passenger window of the Ford Escort test vehicle during the head-on impact number (111A). Also, in the 90 degrees impact (111B) the forward upright post bent and allowed the light to slightly penetrate the windshield even though that barricade had the high cross brace. The impacts of the 7' x 12' barricades (impact numbers 110A and 110B) with two cross braces in the lower position performed better and even though the light impacting the upper part of the windshield in the head-on impact did not penetrate the windshield, it did cause a 2" depression in it. Due to these problems you only requested approval of the 1 ½" to 2" square 16 gauge uprights without warning lights at this time. The damage to the vehicle windshields (except for the case of the high level second cross brace breaking the side window) was caused by the bending of the vertical upright posts allowing the windshield to be struck at high velocity by the posts, panels and lights. Stronger posts, as in your previous testing, control this bending to a greater degree.

The last request, number 8, is by extrapolation from previous acceptances of ALPOLIC® 350 and roll-up signs in the FHWA accepted sign stands. In acceptance letters WZ-100, WZ-100 Amendment 2 and Amendment 3 the mounting of roll-up signs at a maximum of 60" or 84" depending on sign stand model was accepted for models SS548E, SS548AE, SS548CE, SS548CAE, SS548ETL, SS548AETL, SS560, SS560A, SS560E and SS560AE. At the mounting heights of 60" and 84" it is established that the signs and masts detach from the stand and go over the vehicle, so the same is expected in this case. To facilitate achieving these greater than normal mounting heights we would use a lightweight bolt-on interface for the sign that would allow the sign to be attached to the existing roll-up sign mounting adapters. The interface is mounted in the center of the sign so that its configuration approximates that of the ribs of a roll-up sign.

The following are enclosed for reference:

These enclosures support the positions outlined in the requests. Enclosure 6 is a reference revised summary of all the accepted devices in WZ-100 and its revisions as well as this letter.

Testing

Full-scale automobile testing with Ford Festivas was conducted on your company's devices except test 111A and 111B, which used a Ford Escort. 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. Impact speeds were approximately 58 to 60 mph, as measured by calibrated speed radar on site.

The Type III Barricade tests are summarized in the tables below:

Test Number

110A

110B

Barricade Tested

12’ long, 7’ tall, 1.5” 16 gauge non-PSST

12’ long, 7’ tall, 1.5” 16 gauge non-PSST

Barricade Feet

Telescoping, 1.25 into 1.5” PSST

Non-telescoping 1.5” PSST

Barricade Rails

8” x 2” x 144” hollow extruded

½” thick fluted

Crossbars

Two 1.25” 16 gauge 10” and 51” height*

Two 1.25” 16 gauge 10” and 51” height*

Orientation

Head on

End on

Lights?

One 4.4# light atop each post

One 4.4# light atop each post

Signs?

None

None

Extent of contact

Windshield and side window hit

No additional impact

Windshield Damage

2” Deformation

No additional damage

Other notes

None

None


Test Number

111A

111B

Barricade Tested

12’ long, 5’ tall, 1.5” 16 gauge non-PSST

12’ long, 5’ tall, 1.5” 16 gauge non-PSST

Barricade Rails

0.79” Alpolic 350

0.79” Alpolic 350

Crossbars

Two 1.25” 16 gauge 10” and 51” height*

Two 1.25” 16 gauge 10” and 51” height*

Lights?

One 4.4# light atop each post**

One 4.4# light atop each post**

Signs?

33’ square Alpolic 350 signs

33’ square Alpolic 350 signs

Extent of contact

Light struck base of windshield

Light, crossbar hit windshield

Windshield Damage

1.5 inch deformation, cracking

Windshield penetration

Other notes

Side window destroyed

None

* Because the height of the upper cross brace appeared to exacerbate the cracking, the final design will have the upper cross brace located at no higher than 27" above the ground.

** Because the lights were the direct cause of windshield cracking and/or penetration, they will not be acceptable for use with these 16 gauge PSST barricades.

Findings

Damage consisted of moderate cracking for the 16 gauge non-PSST framed barricades. However, there was occupant compartment intrusion in tests 111A and 111B. In order to avoid similar damage, no lights will be permitted on the 16 gauge barricades, and the upper cross brace will be lowered from 51 inches to 27 inches. This will relocate the horizontal structure that caused a hole in the windshield to a lower position, and reduce and relocate the mass impacting the side of the vehicle.

Except as noted above, the results of the testing met the FHWA requirements and, therefore, the devices described in the various requests numbered 1 through 7 above and detailed in the enclosed drawings are acceptable for use on the NHS under the range of conditions tested, when proposed by a State. We also concur in the mounting bracket revision detailed in Request # 8. We also concur in your request to use steel up to a 60 ksi yield in the as-formed cold worked state as the performance of crashworthy Type III barricades tends to improve with greater stiffness.

Please note the following standard provisions that apply to the FHWA letters of acceptance:

Sincerely yours,

/Original Signed by/
~for~

John R. Baxter, P.E.
Director, Office of Safety Design
Office of Safety

9 Enclosures