Driving Surface Aggregate (DSA)

Driving Surface Aggregate (DSA) is a well-graded, unbound mixture of aggregate designed for use as a wearing course on unpaved roads.  DSA is designed to achieve maximum density to resist erosion and traffic wear.  Properly installed DSA roads will have greatly reduced sediment loss and maintenance cycles.  DSA is the only approved surface aggregate for purchase in the Dirt and Gravel Road Program.

Visit the DCNR BOF DSA page for specific specifications and information for use strictly by the DCNR Bureau of Forestry.

Recent Updates

  • Summary of Changes (819 KB): This document summarizes the changes made to the DSA spec on 7/22/20.


DSA must be sampled and tested to insure it meets specifications before it is delivered to a project.  Districts can conduct testing themselves, or enlist the help of the Center.  If a District wishes to use the Center, please contact them as soon as a DSA supplier is chosen (at least 30 days before scheduled delivery.  The Center will act as a “DSA Clearinghouse” for DSA projects in an effort to improve the quality and consistency of Driving Surface Aggregate statewide.  Potential services from the Center include:

  • Visiting and talking with quarries to insure they understand the DSA requirements.

  • Collecting samples and performing testing to insure DSA meets all material requirements before delivery and placement.

  • Keeping records of aggregate testing to avoid duplicating efforts.

  • Establishing a central point of contact for quarries on DSA issues.

  • Assistance with contractor coordination.

  • On-site assistance during DSA placement.

Reference Documents

  • DSA Handbook (2.02 MB): A comprehensive guide to using Driving Surface Aggregate and understanding the SCC DSA specification.  Topics include site prep, purchasing, sampling, placement, compaction, maintenance, and more. (1/21)

  • DSA Handbook Appendices: Provided here separately for download/printing convenience.

  • DSA Tech Bulletin (717 KB): A summary of the Center-developed DSA. Includes material specification, sampling and testing, preparation for placement, placement, compaction, maintenance, and other considerations. (1/21)

  • DSA Checklist for Conservation Districts (199 KB): This document is intended to serve as a guide for Conservation Districts to plan and implement successful Driving Surface Aggregate (DSA) placement as part of a DGLVR project. (2/21)

Other Aggregate Reference Documents

Course Resources

The information below is from the DSA Day course given on February 4, 2021. The course provided a detailed look at Driving Surface Aggregate directed at Conservation Districts. It expanded on the material presented at the ESM training and in the Aggregate Handbook. It is intended as a comprehensive DSA presentation designed for both new hires or as a refresher for Conservation District Staff.

Course Downloads

  • Webinar (233 MB): MP4 format  (~ 2 hours 15 minutes)

Presentation Downloads

Supporting Webinars

  • Aggregates 101: An overview of aggregate specifications and common uses in the DGLVR Program. This webinar discussed both smaller aggregates, large rip-rap, and everything in-between. A great primer for new CD staff. (1/21/2021)