2674 



Chapter 22 



Annual cost per mile of mainline track. — Josephson (1977) also computed 

 the annual cost of wood and concrete ties installed in a heavily travelled mainline 

 track (table 22-23). He found that with 25-year life for the conventional wood tie 

 system, annual costs were 77 percent of those computed for concrete ties with 

 estimated 40-year life. 



Table 22-23 — Annual cost per mile of treated wood and concrete ties at three tie life 

 spans (Data from Josephson 1977) 



System and crosstie life (years) 



Annual cost 

 per mile 



Cost 

 index' 



Wood ties with plates, spikes, and 19- '/2-inch spacing 



20 



25 



30 



Wood ties with plates, spikes, and 21 -'/4-inch spacing 



20 



25 



30 



Wood ties with Pandrol^ fasteners, and 21-'/4-inch spacing 



20 



25 



30 



Concrete ties, 24-inch spacing 



30 



40 



50 



^With index of 100 for concrete ties at 40-year life. 



^A fastener and plate system superior to conventionally spiked plates. 



Dollars 



Dowel-laminated wood crossties. — The manufacture of a 7- by 9-inch cross- 

 tie 8-^/2 feet long calls for a minimum log diameter of about 13 inches. If such 

 ties are dowel-laminated (no glue) from pieces A-V2 by 7 inches in cross section 

 (fig. 20-12), they can be produced from logs only 8.3 inches in diameter. Tie 

 halves can be dowel assembled when green (figs. 20-13 and 18-104D, bottom), 

 air-dried, and treated as an assembly. More than 150,000 of such ties are in 

 service — some for 20 years, and experience with them has been favorable. 

 Research data on assembly procedures and dowel withdrawal forces are given in 

 Howe and Koch (1976); a comparison of dowelling green versus dowelling dry 

 is given in the text related to figure 20-13. Economic analyses of operations to 

 produce dowel-laminated crossties can be found in Koch (1976b) and in section 

 28-18. 



Crossties from parallel-laminated veneer. — Tschemitz et al. (1979) de- 

 scribed the Press-Lam process for making crossties (fig. 22-57 bottom) which 

 embodies stored-heat glue-laminating of thick-sliced veneer (0.25 inch or more 

 thick) using the residual heat of the wood as removed from a veneer dryer. The 

 ideal process is envisioned as a continuous conversion of green veneer into 

 crossties. In a laboratory procedure simulating this process, they found that 



