Can I use my old signs even if they do not meet the requirements of the new 2009 National MUTCD?
With the adoption of the 2009 National MUTCD, there are many signs that no longer conform to the MUTCD. An example is street name signs where the lettering sizes and allowable colors for street name and some guide signs have changed. See the quick answer on that topic.
However, NYSDOT has reviewed this issue, and signs in inventory (or ordered) by January 14, 2010 can still be used, but only until any specific compliance dates which are mentioned in the National MUTCD for those particular signs. Your existing inventory can still be used for most signs. For example, if you have street signs in your inventory with all cap letters, you can put them up if they meet the other standards of the MUTCD.
Above is an example of a sign that has changed in the MUTCD, but can still be used until your inventory is gone or a specific compliance date is reached. The symbol version of the W3-1 sign was introduced in the 2001 NYS MUTCD. The new retroreflectivity standards are an example of a new compliance date. Any yellow backed signs made of engineering grade material must be replaced by January 2015. In addition, the NYS Supplement specifically mentions all text based versions of the stop ahead sign (W3-1a) need to be removed by September 13, 2015 even if they meet the retroreflectivity requirements.