IMPORTANT UPDATE
Major changes have taken place in the way bituminous mixtures are specified, both Coated Macadams and Hot Rolled Asphalts.
These changes were introduced from the 1st.of January 2008, although there will be some delay where existing, binding, contracts refer to BS 4987 and BS 594.
Rather than repeat myself on this page regarding the process of this change may I suggest you study the Summer 2007 Newsletter to get up to date with how/why the changes have taken place.

However do not throw away your BS 4987's and your BS 594's for a while (if ever), as they contain information on good designs and working practice) and it is likely that you will need them to convert your current "well tried" mixtures to the appropriate equivalent new BS EN 13108 specification.

This page will remain for some time, at least until I believe there has been a successful transition between specifying bituminous mixtures from BS 4987 and BS 594 to specifying generic bituminous mixtures from the BS EN 13108 family of specifications.
And we all know, well all those actively involved in the work of maintaining and constructing highways, how long it takes for new "descriptions" of same materials/mixtures to be taken up by the workforce. 

Read on for information on BS 4987 and its past development :-
Please do not be too discouraged by the amount of changes that have occurred in BS 4987 over recent years, they are in fact relatively minor in relation to the overall content of the specification. 
This remains an excellent document for providing information and guidance on the specifying, transporting, laying and compaction of bitumen coated macadam. 
I still believe using the information provided in the standards BS 4987 and BS 594 (hot rolled asphalt) is a good basis to specifying the requirements of bituminous mixtures for road construction and maintenance.
It is my opinion that "converting" existing generic designs for commonly used bituminous mixtures to the new form of specification is the best and most economical method to adopt, especially for local highway networks.
But you, yes you, must be the one to know which is the best bituminous bound material for your site, you should not, and must not, rely on the contractor or supplier to do your job for you. 
Their choice could be influenced by factors other than the most cost effective option to the customer, i.e. you, and whoever you represent, most probably the general public. 
If you need guidance talk to your Materials or Road Pavement Engineer.
It is now time to be concerned about the European BS EN standards for bituminous mixtures as they will be arriving shortly, if not necessarily on time. 
From what I have seen they will not be as dire as predicted, they are a mixture of good news and bad news.
( I particularly appreciate the publication of the standard for stone mastic asphalt, which now allows you to specify the type of SMA you want, although I personally still believe that no SMA's should be porous.)
Do not panic, as I feel that if you know the nature of the bituminous mixture you require you will be able to specify it from an "official" British (European) Standard, which I regard as good practice.
The danger may come, for local authority Engineers and Engineering Technicians, with the introduction of very large "Alliances" of local authorities to create "Framework" deals with large contractors and suppliers.
These "Alliances" will include the Highways Agency as a major, possibly controlling partner, and the Highways Agency may wish to introduce the practice of only permitting proprietary (branded) bituminous mixtures for surface course layers, as is currently the situation with motorways and trunk roads.

THE MOST RECENT UPDATE, (of what appears the most actively updated specification I am aware of, well apart from hot rolled asphalt, and concrete).
BS 4987 : Part 1 : 2005 : Coated macadam (asphalt concrete) for roads and other paved areas - 
Part 1 : Specification for constituent materials and for mixtures

This edition of BS 4987 : Part 1 supercedes the 2003 edition and introduces the concept of factory production control (FPC) tolerances in anticipation of future European Standards for asphalt. 
For grading this will involve selecting a target percentage (%) passing value from within a specified range and applying tolerances to this target. 
Compliance to the specification created from this procedure will assess product conformity.

At the time of writing the only sieve that is required to meet the FPC tolerance in BS 4987 is the 2mm. sieve, this is explained in more detail in the standard.
In due course this may well lead to "different" materials being supplied from different quarries and production plants.

BS 4987, Parts 1 & 2 were previously updated (August 2003) to include changes brought in due to the introduction of BS EN 13043 which will introduce a number of changes relating to the size designations of aggregate, the material description and associated test methods to determine aggregate and mixture performance.
These changes were introduced on the 1st. of January 2004, I suggest you purchase your copy as soon as possible so that you may begin to understand the changes.

I am still including reference to previous recent changes in BS 4987 for background information. 

SUMMARY OF RECENT CHANGES, to specifying Coated Macadam as Asphalt Concrete (from 1st. January 2008)

A great deal of information is presented below on the many bituminous macadams that were specified in BS 4987.
If you wish to use the bituminous mixtures described below in the future, after 1st. January 2008, you will need to convert them to an equivalent bituminous mixture using,
BS EN 13108-1 : 2006 - Bituminous mixtures - Material specifications - Part 1 : Asphalt Concrete
If you were in any way responsible for ordering / purchasing or supervising the laying of bitumen coated macadams you should have had access to both Parts 1 and 2, of BS 4987 of the appropriate edition quoted in the contract.
The information contained in them is excellent, and if you follow their guidance to specify "equivalent"  bituminous mixtures you will not go far wrong, but it would be even better if you could also consult with your Materials Engineer / Technician, if your organisation still has such a person.

Guidance on the transformation of specifying from BS 4987 and BS 594 to BS EN 13108 can be found in, 
PD 6691 : 2007 : Guidance on the use of BS EN 13108 Bituminous mixtures - Materials Specifications

It is also necessary to be aware that the "Part 2's" of both BS 4987 and BS 594 have been combined in to the document, 
BS 594987 : 2007 : Asphalt for roads and other paved areas - Specification for transport, laying and compaction and type testing protocols.

If you are actively involved in the specifying, ordering or use of Bituminous Mixtures you do need to have access to the above new documents.

BE FULLY AWARE ! ! ! ! !
THE INFORMATION BELOW HAS BEEN SUPERSEDED IT REMAINS FOR GUIDANCE PURPOSES ONLY