Putnam Division single tracked from JS to Put Jct.

I searched the forum but couldn't find an answer to this question. I was reading a Put Division ETT from 1918 and it referenced that the line was double tracked from Nepperhan to Ardsley, and then a 1942 Harlem/Putnam ETT that said it was single tracked from JS to Put Junction. Does anyone know when this section was reduced to a single track? I can't find ETTs online from the in-between years or an answer in any other resource. Thanks

Nepperhan to Ardsley was changed from DT to single track between ETT No. 43 of April 26, 1936 and ETT No. 44 of Sept.27, 1936. Refer to Special Instruction No. 110.