View Q&A

1.       Attachment of various transitions to the MGS transition

a.       When developing the MGS approach transition, MGS tested the approach transition with a very stiff, 350 approved transition design. This was done so that successful testing would allow the use of any previously approved thrie beam transition design with the MGS transition on the upstream portion.

2.       W-beam panel spacing

a.       You had asked if the transition requires any no-standard panel lengths to maintain the mid-span splices on the MGS. I don't believe that is true, but it depends on the length of your system. Depending on the length of MGS upstream of the transition, you may have an odd length panel.

3.       Required system length

a.       You asked about the length of system needed to terminate the system. Our recommendation has been that you can begin termination of the system 25' downstream of the start of the transition. The start of the transition is defined as the beginning of the ½ post spacing. Thus, for a standard installation on the upstream end of a bridge, we would recommend 25' upstream of the transition plus 37.5 for the terminal (or longer if you use a longer terminal) for a total of 62.5'.

4.       Downstream anchorage

a.       You had several questions regarding downstream anchorage coming off the bridge. Many of these will depend on the type of installation.

b.      First, if you have two way traffic in this area, you will need an end terminal and can follow the system length guidelines in no. 3 above.

c.       Second, if you are coming off the bridge and don't have anything to shield nor do you have two-way traffic causing the potential for reverse impacts, I don't believe that you would need guardrail on the downstream end.

d.      If you do have to shield the downstream end but don't have potential for reverse impacts, then there are a few options.

                                                               i.      As I mentioned on the phone, no on end terminal end anchorages have been tested for reverse direction impacts. As such, if the end anchorage is in the clear zone we would consider it a potential issue. In this case, we would recommend putting an end terminal that has been tested for reverse impacts on the end because it is in the clear zone and may be impacted.

                                                             ii.      You could use a non-terminal end anchorage if you flared the anchorage out of the clear zone.