2010 Rail Conference Vancouver, BC. APTA/AREMA Joint Recommended Practices: Embedded Track Design. Hugh J. Fuller, PE

Transcription

1 2010 Rail Conference Vancouver, BC APTA/AREMA Joint Recommended Practices: Embedded Track Design Hugh J. Fuller, PE

2 APTA/AREMA Joint Recommended Practices for the Design of Rail Transit Track AREMA / APTA JOINT EFFORT Goal: develop up-to-date recommended track & infrastructure practices for urban rail transit How: combine the membership resources of APTA and AREMA Method: creating up-to-date recommended practices for rail transit design, construction and maintenance using known best practices and research findings

3 The Situation in 2005 The need for up-to-date design and construction standards for street-running, embedded track and non-ballasted tracks of various types was becoming critical Very few individuals with actual streetcar design and/or operating experience are left, and practically none on the rosters of the consulting firms responsible for designing these new systems.

4 The Situation in 2005 The demise of the supply infrastructure, both inhouse at the Agencies and the supply firms, such as Bethlehem Steel, a major supplier of trackwork materials The considerable difference in organizational structure and membership support between AREMA and APTA is a complicating influence

5 The Situation in 2005 No real standard, proven designs Increased the costs of construction because some were over-designed Or under-designed because of lack of experience No single reference that dealt with the multiple complex issues Time to get a grip!

6 The Solution Begins AREMA and APTA agreed to a working relationship to solve this problem Jointly approved Memorandum of Understanding AREMA will develop, codify and publish the up-todate recommended best practices APTA will assist AREMA by providing volunteers from the membership of several APTA Technical Forums

7 The Joint Practices Leadership Co-Chairman Craig Goodall AREMA The Recommended Practices Team Co-Chairman Hugh Fuller APTA AREMA Committee 12 Chairman Keith Powley APTA Track/ N&V Forum Chairman Rick Brown APTA Chief Engineer Martin Schroeder Other AREMA committees will be involved for some topics

8 The Recommended Practices Team The Working Group Leaders Non-Ballasted Track Joe Shaffer, GCRTA Corrosion Control Ed Wetzel, UTRS Sharp Curves Dave Boate, VHB Special Trackwork Transit Tom Lee, Nortrak Clearances Tom Irion, Metro King County Wheel/Rail Interface Brian Whitten, ENSCO Embedded Track Bill Moorhead, Trammco

9 Embedded Track Working Group Embedded Track Issues Track geometry and alignment parameters; ride comfort, safety (may need adjustment regarding lateral acceleration rates and spirals lengths) Vehicle to track interaction; wheel to rail interaction, both vehicle and track maintenance implications, lubrication and friction control, critical wear criteria Design track modulus, vertical and horizontal (this might prove troublesome, as opinions vary considerably) Infill concrete; flangeways; allowance for wheel overhang, track drains, junction boxes, etc. Welded rail: welding, handling, placement, closure welds, de-stressing where possible 9

10 Embedded Track Working Group Embedded Track Issues to be Resolved by Research Wheel/Rail Interface - Can we standardize and reduce the unexplained proliferation of wheel profiles and canted vs. uncanted rail? Rail Welding Can we reduce dipped welds by matching weld hardness to rail hardness? Track Slab Design Do we need reinforcing steel in the track slab? Track Alignment Design Can we increase the speed of light rail vehicles through curves? 10

11 A Few of the Many Wheel Profiles in Use Today Wheel/Rail Interface 11

12 Rail Welding AREMA Manual of Railway Engineering dealing with rail welding qualification and quality control procedures uses the Slow Bend Test The Slow Bend Tests (SBT) requirements specified for Thermite Welding (TW) may require the manufacturers of welding kits to furnish portions that are softer than the joined rails in order to meet the specified minimum deflections for standard and high strength rails APTA/AREMA Embedded Track Working Group is now drafting RP language for publication in Chapter 12 dealing with welding qualification and QC procedures for rail intended for embedment in pavement. 12

13 Rail Welding The majority of the plastic yielding required to meet the SBT may take place in the TW and HAZ s, not the parent rail The current SBT requirements do not have any provision for taking the I X of the rails/tw s being tested into account Almost all European grooved rails have a cross section requiring the TW s to have very high ductility so as to survive the SBD deflection requirements; high ductility often means soft welds soft welds often result in dipped welds When rails are embedded in concrete pavement, the possibility of repair welding dipped welds/haz s is almost non-existent 13

14 14 Rail Welding

15 15 Rail Welding

16 Embedded Track Slab There is no design standard for transit embedded track specifying the dynamic impact factor to be used in designing the track slab. A wide variety of dynamic factors are chosen, resulting in widely varying slab designs for essentially identical support conditions and operating parameters. The designs vary from the heavily reinforced through totally unreinforced. The ETWG is working on rationalizing the dynamic impact factors by obtaining measured vibration testing data and a compendium of factors currently used by designers, and will try to develop a recommended practice by melding those sources into a reasonable and safe set of standards, based on operating conditions. 16

17 17 Embedded Track Slab

18 Curve Unbalance A test program to evaluate ride quality for higher unbalance speeds on curves was organized To determine if a proposed higher unbalance (equivalent to 0.15g) than current AREMA standards (0.10g) is comfortable enough for short ride LRT service A standard LRV, equipped with an accelerometer with recorder, and car speedometer with recorder, operated multiple times over several curves 0.15g lateral acceleration (equal to 9 inches of unbalanced superelevation) vs. 0.10g (comparable to 6 inches unbalance) 18

19 19 Curve Unbalance

20 The Working Group Leaders The Recommended Practices Team APTA/AREMA Joint Recommended Practices for the Design of Rail Transit Track Non-Ballasted Track Joe Shaffer, GCRTA Corrosion Control Ed Wetzel, UTRS Sharp Curves Dave Boate, VHB Special Trackwork Transit Tom Lee, Nortrak Clearances Tom Irion, Metro King County Wheel/Rail Interface Brian Whitten, ENSCO Embedded Track Bill Moorhead, Trammco

21 2010 Rail Conference Vancouver, BC APTA/AREMA Joint Recommended Practices: Embedded Track Design Hugh J. Fuller, PE