buff strength

Buff strength requirements grew out of best-practice design standards during the latter part of the nineteenth century. By the twentieth century, a design limit of {{convert|400,000|lbf|MN}} was required by federal approval agencies. This was upped to {{convert|800,000|lbf|MN}} for certain categories in 1945.{{cite web |last1=Leach |first1=Colin |title=Are US crashworthiness standards "dooming" passenger rail? |url=https://www.railpassengers.org/happening-now/news/blog/are-us-crashworthiness-standards-dooming-passenger-rail/ |website=Rail Passengers Association |access-date=2 July 2023}}

Federal requirements for buff strength were set in 1999 at {{convert|800,000|lbf|MN}} for all passenger-carrying units, unless reduced by waivers or special order. The Federal Static and Strength Regulation (49 Code of Federal Regulations § 238.203) requires that a passenger rail car be able to support a longitudinal static compressive load of {{convert|400,000|lbf|MN}} without permanent deformation.

There are other strength requirements associated with end-structure design. 49 CFR § 238.211 specifies that the cab ends of locomotives, cab cars, and self-powered multiple-unit cars have lead ends capable of supporting {{convert|500,000|lbf|MN}} longitudinal force at the top of the underframe, and {{convert|200,000|lbf|MN}} of force above the top of the underframe.[https://ntl.bts.gov/lib/22000/22600/22604/uscr_std.pdf] Tyrell, David C. (US Department of Transportation). US Rail Equipment Crashworthiness Standards (2 May 2002)

There are multiple certifying and approving agencies in Europe, so universal agreement on strength standards is not guaranteed. A 1977 German standard (VÖV 6.030.1/1977) presented values which have been followed by some other countries. The document was revised in 1992 and is presently known as VDV Recommendation 152 - Structural Requirements to Rail Vehicles for Public Mass Transit in Accordance with BOStrab.

In 1995 the European Common Market Committee for Standardization issued a draft document, Structural Requirements of Railway Vehicle Bodies. It mandated differing design loads for vehicles in differing categories, ranging from {{convert|45,000|lbf|MN}} for tramways to {{convert|450,000|lbf|MN}} for passenger coaches and locomotives.[http://onlinepubs.trb.org/onlinepubs/tcrp/tsyn25.pdf] Light Rail Vehicle Compression Requirements. Transit Cooperative Research Cooperative, The [United States] Federal Transit Administration (1997)

In general the European approach to crashworthiness of passenger coaches puts more emphasis on crumple zones rather than buff strength, meaning that the required design loads are less than those in the United States. This is generally agreed to reduce construction costs.{{cite web |last1=Leach |first1=Colin |title=Are US crashworthiness standards "dooming" passenger rail? |url=https://www.railpassengers.org/happening-now/news/blog/are-us-crashworthiness-standards-dooming-passenger-rail/ |website=Rail Passengers Association |access-date=2 July 2023}}

{{div col|colwidth=30em}}

• Compressive strength
• Container compression test
• Crashworthiness
• Deformation (engineering)
• Headstock (rolling stock)
• Railworthiness

{{div col end}}

{{reflist}}

Category:Rail transport

Category:Deformation (mechanics)

{{loco-stub}}