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ODOT is talking about making this design a standard in MOT situations on structures that have limited cross sections.
This predates me as a member of the pooled fund, but this barrier looks promising to us.
Can you provide us with any addition information and the history of this project?
Did you select this width because of the availability of H-piles?
Do you think the width of this barrier could be reduced even more?
Do you know any state are using this design?

http://safety.fhwa.dot.gov/roadway_dept/policy_guide/road_hardware//barriers/pdf/b117.pdf

From my recollection, MwRSF crash tested a free-standing version of Iowa's Steel H-Pile Temporary Barrier system in the late 80s. The Iowa DOT developed the H-Pile system and then hired MwRSF to conduct the compliance testing according to the AASHTO Guide Specifications for Bridge Railings. As I recall, one pickup truck test was successfully performed at the target impact conditions of 60 mph and 20 degrees. The joint detail between sections was both cumbersome but very strong. Steel angled plates were used to interconnect the sections using a large number of bolts which did not allow for much construction tolerance for misalignment and/or uneven surfaces. However, the joint detail did transfer load well across the joints to adjacent barrier segments. For free-standing applications, this barrier system with rigid joint detail resulted in dynamic barrier deflections of approximately 18 in.

Many years later, the IA DOT and the Pooled Fund program had MwRSF do some follow-on research with this general barrier system. This later study included a simplification of the joint detail as well as the incorporation of a tie-down system, then followed by full-scale crash testing according to NCHRP Report No. 350. Although the joint detail was simplified, the full-scale crash tests were only performed for the tied-down design variation. Upon completion of the testing, the modified design was shown to greatly reduce barrier deflections when subjected to a 2000P pickup truck impact at the target conditions of 62 mph and 25 degrees.

Two research reports have been prepared over the years to document the findings noted above. If desirable, MwRSF could send electronic copies of these to you. The later report would likely have been sent to Dean Focke shortly after the project was completed.

I am only aware of this barrier system being used in the State of Iowa. In order to obtain further information of its use, I have copied this email to our colleagues within the Iowa Department of Transportation with the hope that further light could be shed on its current use.

As noted previously, the sizing of the steel H-sections was made by the Iowa DOT. As I recall, the system width was approximately 14 in. wide. Thus, I am reasonably confident that a new or revised steel system (possibly with concrete ballast similar to this design) could be developed with a system width 1 to 2 in. narrower than used in the current Iowa design.