Another thing is also during the era of the older fleet there was far fewer vegetation than there is today, despite the great tree hunt from a few years back, and efforts today to curtail growth along the ROW. While the RR can wack things within their property, falling leaves don't respect property lines, and you don't have many folks who would burn wood like you would in the past. If you look at historical pictures from then and now, you'll see a big difference in how much vegetation has overtaken certain areas of the railroad.
What I'm curious about is what's the consensus on the different methods the LIRR has used, Sandite, washing and now the laser. What's the best method? I wonder what's the most persistant, and even though the RR is doing it's best to run these extras on the system (I see them during the day, and given the traffic level, that's very ambitious), isn't no matter what method you use, a few trains going by and whatever you did is going to get nullified?