Hi Guys (and girls!!) I have two short questions on bridges: 1. What is the use of the guard rail? Someone told me to hold the tie inplace, others says to prevent derailled wheels from hitting the bridge's structure... Who's right? 2. What mean "pony truss"? Thank you, Yvan-Martin
<blockquote>quote:</font><hr>Originally posted by Yvan-Martin Levesque: I have two short questions on bridges: 1. What is the use of the guard rail? Someone told me to hold the tie inplace, others says to prevent derailled wheels from hitting the bridge's structure... Who's right? <hr></blockquote> The 'guard rail' laid just inside the running rail is used to hold a derailed car in the track area rather than having it strike the bridge sructure or fall off the trestle. <blockquote>quote:</font><hr> 2. What mean "pony truss"? <hr></blockquote> A quote from the NMRA Data Sheets... "Thru Truss Bridges are used when greater under clearance is wanted. Trusses are located above the track and the train between them, or "thru" the bridge. A pony truss is a thru truss too shallow to permit top lateral bracing." When clearance is required under the bridge, trusses may be used above the bridge deck. Normally, this would have cross supports above the clearance for the train. However, when the clearances won't permit the overhead bracing, shorter side trusses are used. This is a Pony Truss. Generally, used on short spans. Sometimes the Pony Truss is used for short spans as a cost saving measure Hope this helped. Roger Roger Hensley - rhensley@anderson.cioe.com == http://cid.railfan.net/eci_new.html == == East Central Indiana HO Scale Railroad == [ 01 September 2001: Message edited by: rhensley_anderson ]</p>
