State of the Art in Light Rail Vehicle Crashworthiness Standards

John D. Swanson &

John C. Smatlak

Principal Consultants

SNC-Lavalin Rail & Transit

Los Angeles, CA

Application of ASME RT-1 and EN 12663-1 / EN 15227

Horse Drawn Cars 1887 First Electric Cars 1893

Two Truck Car 1913 Two Truck Car 1922

Evolution of Crashworthiness Standards: First Era (pre-1952)

No structural strength or crashworthiness standards

Evolution of Crashworthiness Standards: First Era (pre-1952)

No structural strength or crashworthiness standards

Last Phoenix Streetcars (built

1928, in service until 1948)

TTC PCC Car (built 1951, in

service until 1992)

Propulsion

Horse

Cable

Electric

Carbody

Wood

Steel underframe

All steel

Short, light weight, low

capacity, slow

Longer, heavier, higher

capacity, faster

Evolution of Crashworthiness Standards: Second Era (post-1952)

Streetcars disappear from most US cities

Evolution of Crashworthiness Standards: Second Era (post-1952)

Streetcar development continues in Europe

High Floor Articulated Tram-1980’s

Wire-free 2003

High Floor Articulated Tram w/ Trailer – 1950’s

100% Low Floor Tram 199470% Low Floor Tram1987

Evolution of Crashworthiness Standards Third Era (1972)

UMTA US Standard LRV Development

• First time end sill buff strength of 2g required

• Basis for requirement not known

• No crashworthiness requirements

Evolution of Crashworthiness Standards Third Era (1978)

California Public Utilities Commission General Order 143

• 1978; only 7 LRT/Streetcar systems in the US; low-floor vehicles didn’t exist yet

• First time 2g end sill strength made mandatory

• Applies only to California, but was widely adopted by other states and carbuilders

• Became the defacto structural standard

Evolution of Crashworthiness Standards Third Era (1981)

UMTA Light Rail Transit Car Specification Guide

First crashworthiness requirements recommended:

•2.5 mph solid object impact with vehicle end, zero damage

•10 mph solid object impact with vehicle end, permanent deformation first two feet, damage confined to first four feet, no hazardous high voltage electrical damage

2g buff load did not become national standard, crashworthiness requirements not implemented

Evolution of Crashworthiness Standards Fourth Era (1995)

HBLRT / NCS LRT Development

1995: Hudson Bergen

LRT / Newark City

Subway Projects

Set the Stage

First modern vehicles to have lower buff strength (88,000 lb) and crashworthiness features:

•Energy absorbing elements

•Controlled collapse during a collision

•12.5 mph collision scenario

•No sharp corners, resilient interior fittings

Evolution of Crashworthiness Standards Fourth Era (1997)

TCRP Synthesis 25 “LRV Compression Requirements”

• Buff strength just one measure to protect passengers

• Others are car end energy absorbers, collapsible vehicle ends, effective brakes, softly padded interiors, automation and driver training

• Safe operations possible w/ vehicles built to 0.5g

• Potential benefits are lower vehicle weight, less wear, lower energy consumption, reduced capital / operating costs and greater safety.

Evolution of Crashworthiness Standards Fourth Era (1999 - 2009)

ASME RT-1 Safety Standard

HBLRT vehicle structural and crashworthiness design became basis of new RT-1 Safety Standard for Structural Requirements for Light Rail Vehicles

•Gaining consensus / acceptance difficult

•More than a dozen drafts

•Resistance to reduction in buff strength

•Approved as a national standard in 2009

• First use of ASME RT-1 (draft 5)

• First use of shock absorbing bumper

• Enclosed front, folding couplers

Evolution of Crashworthiness Standards Fourth Era (2003 - 2008)

Phoenix Light Rail Leads the Way

Evolution of Crashworthiness Standards Fourth Era (2009)

ASME RT-1 Highlights

Core Crash Energy Management (CEM) principles:

•Minimize injury to occupants

•Minimize loss of occupant volume

•Provide for progressive collapse

•Improve pedestrian and road traffic safety

•Protect the Operator

Two tables define structural loads and collision scenarios (buff load= 300 kN Streetcars, 400 kN LRVs)

Evolution of Crashworthiness Standards Fourth Era (2008)

EN 15227 Crashworthiness Highlights

EN 15227:2008 – Railway Applications – Crashworthiness Requirements for Railway Vehicle Bodies

•Covers all categories of rail vehicles

•Emphasizes crash avoidance with passive safety requirements which vary depending on vehicle category

•CEM approach similar to RT-1 but not directly equivalent

Evolution of Crashworthiness Standards Fourth Era (2008)

EN 15227 Crashworthiness Highlights

Vehicle Categories similar to RT-1 but not directly equivalent:

•Category C-IV: Light rail vehicles designed to operate on dedicated urban networks interfacing with road traffic (tramway vehicles)

•Category C-III: Light rail vehicles designed to operate on urban and/or regional networks, in track-sharing operation, and interfacing with road traffic (Tram trains, peri-urban tram)

Evolution of Crashworthiness Standards Fourth Era (2010)

EN 12663-1 Structural Highlights

EN 12663-1:2010 – Railway Applications – Structural Requirements for Railway Vehicle Bodies

•Covers all categories of rail vehicles

•Similar to RT-1, but not directly equivalent

•Covers vertical, end sill, truck attachment and equipment attachment loads

•Does not cover coupler, collision post, side wall or roof loads

Evolution of Crashworthiness Standards Fourth Era (2010)

EN 12663-1 Structural Highlights

Vehicle Categories similar to RT-1 but not directly equivalent:

•Category P-V: Tramway vehicles •Category P-IV: Light duty metro and heavy duty tramway vehicles

**When allowing the use of Euro Norm equivalents to RT-1 take great care that the correct category of vehicle is utilized**

• Load tables split into separate structural and crashworthiness requirements

• Assigned Weight (AW0-AW4) loadings changed to ready to run, seated load and car volume capacity. Avg. passenger weight increased to 79.5 kg (175 lb)

• Anticlimber load cases removed, replaced with maximum wheel lift performance (similar to EN 15227)

Evolution of Crashworthiness Standards Fifth Era (2015)

ASME RT-1: 2015 Update

• Collision scenarios now between two ready-to-run trains (maximum number of cars used in operation) with one stationary and both with full service brakes applied

• Truck to carbody attachment loads revised

• Collision Zone 2 and Zone 3 acceptance requirements revised

Evolution of Crashworthiness Standards Fifth Era (2015)

ASME RT-1: 2015 Update

• CEM principles adopted worldwide

• ASME RT-1 and EN 12663/EN15227 are converging, but not directly equivalent

• European vehicle designs dominate the world market

• The US buys less than 15% of the LRT vehicles produced

Conclusions

• European vehicles can be made equivalent to RT-1 by adding critical requirements

• Great care must be taken in choosing the correct vehicle category when using EN standards

• 2g buff strength requirement in CPUC General Order 143 remains an obstacle to widespread adoption of RT-1

Conclusions