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We are working on getting the aluminum ped fence drawings and have some questions.

What would be the minimum pad dimensions the fence can be placed on?  Most of our sidewalks are less than 6” deep.  To retrofit this design we would probably need to pour a separate pad for the ped fence.

Does MwRSF have recommendation on how to place the ped fence relative to curb and gutter.  I know we have not tested it with curb and gutter. But since we develop the ped fence, MwRSF and other have done a lot of modeling with curb and other devices.  I was hoping that some of that computer modeling could be used here.

We want to also verify the gap distance between segments.  On the test drawings there is a 7 ½” measurement between segment.  However, the scale of the top view make it difficult to determine where to measure the 7 ½”.  In other parts of the report there is a mention of 5 ½” between segments.  It is not clear where to measure the 5 ½”.

Also I remember discussing offsetting each section of rail to minimize deceleration with head on impact.  Am I remembering this correctly?

I have attached an electronic PDF copy of the 2017 TRB IRSC-PE refereed conference paper that was contained in the E Circular.

My initial comments are contained below in RED. However, I plan to discuss a few of the questions with the team and provide additional feedback soon.

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What would be the minimum pad dimensions the fence can be placed on?  Most of our sidewalks are less than 6” deep.  To retrofit this design we would probably need to pour a separate pad for the ped fence.

 **The paper references a minimum pad thicknesses of 7 in. as the anchor depth for the high-strength ASTM A193 B7 ½-in. diameter threaded steel anchors was 5 in. A chemical epoxy adhesive with a 1,450-psi minimum bond strength was used.

**More to follow in near future on size of pad (length x width) when unreinforced with posts near ends, edges, and/or construction joints.

Does MwRSF have recommendation on how to place the ped fence relative to curb and gutter.  I know we have not tested it with curb and gutter. But since we develop the ped fence, MwRSF and other have done a lot of modeling with curb and other devices.  I was hoping that some of that computer modeling could be used here.

**More to follow in near future on whether any changes are needed when raising the system 6 in. relative to a nearby curb & gutter line as well as when placed farther away from a curb & gutter line but still 6 in. higher. Note that the system is a channelizer and not a barrier.

We want to also verify the gap distance between segments.  On the test drawings there is a 7 ½” measurement between segment.  However, the scale of the top view make it difficult to determine where to measure the 7 ½”.  In other parts of the report there is a mention of 5 ½” between segments.  It is not clear where to measure the 5 ½”.

 **The upright posts had a clear spacing of 5½ in., as measured between the external sides of two adjacent posts at a joint. The center-to-center spacing of two adjacent posts at a joint was 7½ in. The base plate spacing was not part of either dimension noted previously. I went to review the bogie testing details in the report to see the 7½-in. c-c spacing.

Also I remember discussing offsetting each section of rail to minimize deceleration with head on impact.  Am I remembering this correctly?

**We had previously discussed two options that would be expected to improve performance of the system.

**Option 1 - The first panel would have a slight lateral shift left of the panel away from a centerline but still parallel. The second panel would then have a slight lateral shift right of the panel away from a centerline but still parallel. This pattern would repeat.

**Option 2 – The first panel would have its upstream end on the centerline but its downstream end laterally to the left. The second panel would have its upstream end on the centerline but its downstream end laterally to the right. This pattern would repeat.

**We may have drafted these concepts into a sketch for a follow-on paper. However, we never completed the updated paper, and it remains on our future paper list.

 I have added further thoughts to the original email respose.

I have attached an electronic PDF copy of the 2017 TRB IRSC-PE refereed conference paper that was contained in the E Circular.

My initial comments are contained below in RED. My refine comments are contained below in GREEN.

What would be the minimum pad dimensions the fence can be placed on? Most of our sidewalks are less than 6” deep. To retrofit this design, we would probably need to pour a separate pad for the ped fence.

 **The paper references a minimum pad thicknesses of 7 in. as the anchor depth for the high-strength ASTM A193 B7 ½-in. diameter threaded steel anchors was 5 in. A chemical epoxy adhesive with a 1,450-psi minimum bond strength was used.

 **The original research was performed on a 20- to 24-in. thick, unreinforced concrete tarmac at the outdoor proving grounds. The minimum thickness guidance was likely determined using a 5-in. anchor embedment plus a 2-in. bottom cover to reduce risks of concrete punch-through under drilling operations. Under crash loading, the posts are designed to breakaway. The anchorages were designed to conservatively meet the pedestrian loading. If reinforced concrete foundations are used to support the pedestrian railing/channelizer, then limited concrete damage should occur under impact loading, and no damage should occur under pedestrian loading. If unreinforced concrete foundations are used to support the pedestrian railing/channelizer, then normal cracking of the concrete pad may occur over time and/or during impact loading. The crashworthiness of the breakaway channelizer should not be affected.

**Over time, cracking around the anchors may over reduce the foundation’s capacity to resist the expected pedestrian loading as anchors may align on a crack that widens. Impact loading would likely cause increased damage to an unreinforced foundation. The durability of unreinforced concrete foundations decrease over time and through changes in environmental conditions and temperatures. Any steel reinforcement in the foundation would be beneficial.

Does MwRSF have recommendation on how to place the ped fence relative to curb and gutter. I know we have not tested it with curb and gutter. But since we developed the ped fence, MwRSF and others have done a lot of modeling with curb and other devices. I was hoping that some of that computer modeling could be used here.

 **The research team has discussed this question and believe that it safe to place the pedestrian railing/channelizer within 2 to 3 ft of the 6-in tall curb and raised sidewalk. Beyond that distance, the safety performance of the system on a raised sidewalk is unknown as the impacting vehicles may strike the system higher on the structure. Without further investigation, we are uncertain as to whether vehicle instabilities occur with lighter mass vehicles due to delayed fracture of posts under oblique loading scenarios.

We want to also verify the gap distance between segments. On the test drawings, there is a 7½” measurement between segments. However, the scale of the top view makes it difficult to determine where to measure the 7½”. In other parts of the report, there is a mention of 5½” between segments. It is not clear where to measure the 5½”.

 **The upright posts had a clear spacing of 5½ in., as measured between the external sides of two adjacent posts at a joint. The center-to-center spacing of two adjacent posts at a joint was 7½ in. The base plate spacing was not part of either dimension noted previously. I went to review the bogie testing details in the report to see the 7½-in. c-c spacing. **It should be noted that the vertical gap between end posts must also meet the 6-in. sphere pass-through requirement.

Also I remember discussing offsetting each section of rail to minimize deceleration with head on impact.  Am I remembering this correctly?

**We had previously discussed two options that would be expected to improve performance of the system.

 **Option 1 - The first panel would have a slight lateral shift left of the panel away from a centerline but still parallel. The second panel would then have a slight lateral shift right of the panel away from a centerline but still parallel. This pattern would repeat.

 **Option 2 – The first panel would have its upstream end on the centerline but its downstream end laterally to the left. The second panel would have its upstream end on the centerline but its downstream end laterally to the right. This pattern would repeat.

 **We may have drafted these concepts into a sketch for a follow-on paper. However, we never completed the updated paper, and it remains on our future paper list.