The house I live in had thin glass in the windows so I removed that and used a router (one of these things)
to make a deeper rebate in the sash so the much thicker glass could fit in. You can do it deep enough for double glazed. Once I had the thicker glass in it cut down road noise by about 75%. I used small stainless nails to hold it in place then a silicon type product to water proof it. Much less drama (and money) than getting replacement sashes and frames.