Railroad Bridge Walkway: Post-to-Tie Connection

[anominal]

I've been sifting through AREMA and have found no help:

We're using angles as posts, bolted through timber bridge ties, for a walkway railing. I have to evaluate the connection for a 200# transverse load applied at the point of connection for the top rail.

I don't know if the allowable unit stresses in the AREMA "Timber Structures" volume apply to bridge ties. I fear ties are not graded for strength like structural timber, which seems to be the focus of these tables.

See:
Table 7-2-13
Table 7-2-15
Table 7-2-16

 

[MiketheEngineer]

Do you have any idea what the grade of timber is??

About the worst I have seen is an Fb in 500 psi range... but a good dense Pine or Fir can exceed 2000 psi.

 

[anominal]

All I know is that we're specifying oak ties. Not sure about the grade.

 

[MiketheEngineer]

Find the worst case OAK and maybe go from there??

 

[anominal]

That's my inclination. So you do believe the tables I listed are applicable to bridge ties.

 

[ToadJones]

be hard to say wouldn't it? Aren't those ties soaked in creosote?

 

[anominal]

ToadJones:
They are indeed.