Stone has an unlimited durability. It is being used as loading ele- 
ment in connection with brushworks or for bracing of steep banks or slopes. 
As to the use of asphalt for coastal groins it is still too early 
to express a conclusive opinion in view of existing experience and dis- 
appointments with other construction materials. 
The economic life of a structure fixes its maintenance cost. 
i, Artificial Sand Addition - The artificial addition of sand 
in regions with a deficient balance of natural sand supply, is the most 
recent method of coastal protection, despite the fact that several decades 
earlier dredged material was discharged for such purpose on beaches of the 
Baltic and North Seas with good results. The time is too short to report 
on the results of this method of protection. The basic cause of the natural 
sand deficiency will not be alleviated by abundant sand importation, and 
this operation would have to be periodically repeated. However, sand has 
the advantage when compared with other construction materals because of 
its natural behavior in places where sand was located before. It is a 
question of economics whether or not artificial importation of sand should 
be recommended, The volume required and the transportation distances 
figure decisively in such calculations. 
j. Costs - We find only one article on the cost of construction 
and maintenance of coastal structures in the entire German literature. This 
was written by Hibben (1935) and deals with the installation at Borkum. 
Up to 1916 the cost for the maintenance of protective installation and for 
repair of storm damages amounted to 42% of the total expenditures for new 
and additional construction. However, it is pointed out that "the latter 
mentioned additional construction has to be included in maintenance cost". 
This proved to be right, as according to another unpublished statement, 
the ratio of maintenance to new construction costs up to 1957 was 5 to 4. 
The costs for Borkum cannot be generalized, yet it offers an insight into 
the range of costs which may apply also to seagroins. 
Initial construction cost for a beach groin is so high that the im- 
portation of sand by pipeline dredging proves to be entirely competitive. 
Comparison of costs requires the consideration of the limits of restora- 
tion. Fulscher, as a responsible referent in the Central Administration, 
proposed as early as 1905 to analyze the problem of cost. 
V. CONCLUSION 
Up to the present, it has not been possible, from available informa- 
tion, to clarify the complex problems occurring on sandy beaches and to 
interpret all cases properly. It is generally admitted, in view of the 
fact that the literature on the effect of beach groins is encumbered with 
so many statements and hypotheses, that it is necessary to either sub- 
stantiate or invalidate those statements analytically by measurements 
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