ROADS 159 



7. Why should road gravel vary in size? 



8. Why is it best not to use too large pebbles? 



9. What is common binding material? 



10. How much binder should be used? 



11. Why should a gravel road be thoroughly underdrained? 



12. Describe the surface method of constructing gravel roads. 



13. What thickness of gravel is usually applied? 



14. Describe the trench method of constructing gravel roads. 



15. How much do gravel roads cost? 



16. How are gravel roads maintained? 



