area. The as so dated parking facilities 

 should be placed on the uplands. The 

 impact of one ramp may be minimal. If 

 the area becomes an attractive launch- 

 ing area, then it may attract commercial 

 facilities. The habitat alterations increase 

 accordingly. 



S tructural and Nonstructural 

 Alternatives 



The purpose of most ramps is the 

 launching and retrieval of small craft. 

 This same function can also be perform- 

 ed by a hoist which can pick the boat 

 off a trailer and swing it into the wa- 

 ter. Such a device usually requires a 

 pier or other structure to allow access 

 to water of sufficient depth. A sling 

 would be more applicable in areas where 

 there is relatively deep water close to 

 shore. 



A marine way (dolly) is another 

 viable alternative which avoids the nec- 

 essity of constructing a pier and/ or 

 dredging to reach water of sufficient 

 depth (Figure 39). This launching tech- 

 nique involves lifting the boat with a 

 sling onto a platform mounted on rails 

 (the dolly). Launching is achieved by 

 running the boat down'the railed struc- 

 ture and into water of sufficient depth. 

 This technique has the advantage of al- 

 lowing launching in areas with shallow 

 slopes or at low tides. It is generally 

 not feasible to cross extensive tidal 

 flats with a ramp. 



Regional Considerations 



Most of the literature contained in- 

 formation applicable to all of the coastal 

 regions. There was some information 

 specific to the north Pacific and Gulf 

 coast (Coastal Regions 1 and 3). In 

 the Puget Sound area of Coastal Region 

 1, siting ramps on "accretional or roll- 

 back dry beaches" should be avoided 

 due to possible changes in beach profile 

 (Bauer 1973). Less than 4% of the 

 shoreline in this area consists of dry 

 beaches. If ramps are placed in this 

 area, the protective structures should 

 be constructed so they do not interfere 

 with "beach drift action." Bauer (1973) 

 suggests considering "flexible-contour 

 bolt and hinge segmented ramp pads 

 that can be adapted to beach profile 



changes, "and also recommended that ramps 

 be located in between "drift sectors" or 

 "independently operating erosion-trans- 

 port-accretion beach systems." 



In the New Orleans District of the 

 U.S. Army Corps of Engineers in the 

 Coastal Region 3, the most common type 

 of ramp consists of compacted gravel or 

 shell covered by concrete (Carstea et 

 al. 1976). These authors cave the di- 

 mensions of a typical boat ramp as 10 to 

 12 ft (3 to 4 m) wide and 40 ft (12 m) 

 long. A typical seaplane ramp is 25 to 

 30 ft (8 to 9 m) wide and 55 to 60 ft 

 (17 to 18 m) long. Concrete and timber 

 seaplane ramps are similar to the boat 

 ramps. 



Shore profiles encountered in the 

 various coastal regions will determine 

 the design and feasibility of ramps and 

 the desirability of utilizing alternate 

 structures, such as slings and dollies. 



PIERS, PILINGS AND OTHER SUPPORT 

 STRUCTURES 



Definitions 



A pier is a structure, usually of 

 open construction, extending into the 

 water from the shore. It serves as a 

 landing and mooring place for vessels or 

 for recreational or commercial uses. 

 This definition of a pier includes tres- 

 tles, platforms, and docks extending 

 into the water for similar purposes. The 

 definition does not include bridge 

 piers. Floating structures anchored with 

 pilings are sometimes called floating 

 piers. Sometimes jetties, groins, and 

 other structures built primarily for 

 coastal protection purposes are incor- 

 rectly called piers. 



A pile is a long heavy timber, 

 steel, or reinforced concrete post that 

 has been driven, jacked or jetted, or 

 cast vertically into the ground to sup- 

 port a load. A pile structure will nor- 

 mally be an open structure where water 

 can circulate between the individual 

 piles or pile clusters. Sheet piles are 

 steel or concrete sheets or slabs which 

 are driven edge to edge in a straight 

 row to form a bulkhead or wall. They 

 can also be driven in circles, squares, 

 or in other closed shapes to form bridge 



78 



