the fill-road and ditching in the south 

 marsh appeared to be similar to the 

 Evans Creek site. 



Two sites were also investigated at 

 Cow Creek. Both of the sites are land- 

 ward of a fill-road completed 4 yr prior 

 to the study and paralleling the coast. 

 What is referred to as the "open area" 

 is 1 mi (1.6 km) from the Gulf along 

 Cow Creek. The study area is connect- 

 ed to the seaward side by a 6-ft(1.8-m) 

 wide culvert. Salinity, plant zonation, 

 and pattern and abundance of molluscs 

 were the same on both sides of the road 

 and are, therefore, assumed to be unaf- 

 fected by the fill-road. 



What is referred to as the "closed 

 area" is approximately 0.8 mi (1.3 km) 

 from the Gulf. A 3-ft (0.9-m) wide and 

 12-ft (3.7m) wide culvert facilitates the 

 drainage. Fill canals are located on both 

 sides of the roadway. Sheet flow ap- 

 pears to be restricted from the land- 

 ward side of the roadway, as evidenced 

 by the presence of salt intolerant spe- 

 cies. Clewell et al. (1976) state that 

 the canals are intercepting much of the 

 incoming tidal water. 



Clewell et al. (1976) conclude that 

 if the tidal flow through a fill-road is 

 unrestricted, marsh will not be signifi- 

 cantly affected, other than within the 

 area where construction of the fill-road 

 took place. 



CASE HISTORY-BRIDGES AND CAUSE- 

 WAYS IN COASTAL REGION 4 - SOUTH 

 FLORIDA 



The State of Florida Department of 

 Transportation (FDOT) in cooperation 

 with the U.S. Department of Transpor- 

 tation - Federal Highway Administration 

 (FHA) contemplates replacing 37 of the 

 44 bridges along 87 mi (140 km) of the 

 Overseas Highway (State Road 5, U.S.I) 

 from Key West to Key Largo. The local- 

 ized impacts due to construction and 

 operation and regional impacts due to 

 cumulative affects of the many bridges 

 and associated causeways make an inter- 

 esting case history study. Impacts dis- 

 cussed in this case history study will 

 be limited to terrestrial and aquatic im- 

 pacts. Unless otherwise noted, the 



source of information is "Negative De- 

 claration State Road 5 (U.S. 1) Bridge 

 Replacements" (H.W. Lochner, Inc., 

 Consulting Engineer 1975). 



Around the turn of the century, 

 Henry N. Flagler, one of the founders 

 of Standard Oil and builder of the Flor- 

 ida East Coast Railroad from Jackson- 

 ville to Miami, decided to extend his 

 railroad to Key West. The resulting 

 single track Overseas Railroad, complet- 

 ed in 1912, covered a distance of 156 mi 

 (251 km). In September 1935, a hurri- 

 cane washed out the track and roadbed 

 in the 30-mi (4£-km) stretch from Key 

 Vaca to Plantation Key. It was decided 

 that the railroad would not be rebuilt. 



Overseas Road and Toll Bridge 

 Commission purchased the right-of-way 

 and the associated physical assets and 

 directed their efforts toward converting 

 the remaining railroad structures to 

 highway structures. The new highway 

 was opened to Lower Matecumbe Key in 

 1936, to Big Pine Key in 1938, and to 

 Key West in 1944. The bridge-causeway 

 system supplies access between mainland 

 and Keys for residents and vacationers. 

 It carries an aqueduct which assures a 

 supply of fresh water to the Keys. 



Many of the bridge structures 

 have deteriorated severely since con- 

 struction more than 30 yr ago. Between 

 1963 and 1973, a total of $10,000,000 

 was spent for bridge repair. This sum 

 equals the original cost of the highway 

 system. It is estimated that maintenance 

 costs for the period from 1975 to 1985 

 will be $84,000,000. In 1974, Congress 

 passed a highway bill which appropriat- 

 ed $109,200,000 for the replacement pro- 

 ject. In addition to the positive cost- 

 benefit analyses between replacement 

 and maintenance, there is definite con- 

 cern that the deteriorating structures 

 might experience structural failure, pos- 

 sibly causing loss of life or serious in- 

 jury. It would also result in loss of 

 access between the Keys and the main- 

 land, as well as possible health hazards 

 in the Keys due to a loss of the potable 

 water supply. 



The proposed reconstruction pro- 

 ject will replace 37 of the 44 bridges 



117 



