Early works Responsibility for construction on Tinian was assigned to the 6th Naval Construction Brigade, under the command of
Captain Paul J. Halloran. the latter, under Commander Jonathan P. Falconer, the 67th, 110th and 121st Naval Construction Battalions. A third regiment, the 49th Naval Construction Regiment, was formed on 2 March 1945 from the 9th, 38th, 110th and 112th Naval Construction Battalions, under Commander Thomas H. Jones. Elements of the 18th and 121st Naval Construction Battalions landed on Tinian with the assault troops on 24 July, with the remainder arriving on 27 July. That day, the 121st commenced the rehabilitation of the airstrip in the north, filling in the bomb and shell craters. By that evening, an airstrip long and wide was ready for use, and it was fully restored to its full length the next day. On 29 July, a P-47 landed and took off again. The
9th Troop Carrier Squadron was brought forward from
Eniwetok, and its
Douglas C-47 Skytrains, together with the
Curtiss C-46 Commandos of
VMR-252, delivered 33,000 rations from Saipan on 31 July. On the return trip they carried wounded to hospitals on Saipan. A third battalion, the 67th Naval Construction Battalion, arrived on 2 August. With the island declared secure, the seabees were released from the control of the
V Amphibious Corps to the 6th Naval Construction Brigade, which became operational on 3 August. Additional naval construction battalions arrived over the following weeks and months: the 92nd from Saipan in August and September; the 107th from
Kwajalein on 12 September; the 110th from
Eniwetok in September and October; the 13th and 135th on 24 October; the 50th on 19 November, the 9th on 1 December, and the 38th and 112th on 28 December. The Seabees completed and extended the second Japanese airstrip in the north, which became North Field Strip No. 3 in September. They then rehabilitated the severely damaged airstrip in the west as a airstrip for fighter planes. Navy patrol planes commenced operations from the two North Field airstrips, but work to upgrade them to handle the B-29s could not be carried out while they were in use. A new runway was built in the west, which became known as West Field Strip No. 3. The airstrip was completed on 15 November. In addition to the runway, there were of
taxiways, 70
hardstands, 345
Quonset huts, 33 repair and maintenance buildings, 7
magazines and a tall
control tower.
Airfields Responsibility for the development of North Field was assigned to the 30th Naval Construction Regiment. Falconer divided the work into phases, and designated a battalion as the "lead" on each phase, with overall responsibility for the work in the phase, and the other battalions acting as subcontractors. The first phase, the extension of North Field Strip No. 1 to , along with the construction of the necessary taxiways, hardstands and
aprons, was assigned to the 121st Naval Construction Battalion. The work was completed nine days ahead of schedule, and the first B-29 landed on the completed airstrip on 22 December. The next phase was the extension of North Field Strip No. 3 to . This work was undertaken by the 67th Naval Construction Battalion as the lead battalion, and was completed on a day ahead of schedule on 14 January 1945. The 13th Naval Construction Battalion became the lead on the third phase, the construction of North Field Strip No. 2, between and parallel to the other two runways. The final runway, parallel to the other three, was assigned to the 135th Naval Construction Battalion and was completed on 5 May 1945, five days ahead of schedule. All four strips were widened to . Early works on the harbor were carried out by the 50th and 92nd Naval Construction Battalions, which drove of
piling that eventually formed part of the south bulkhead, and by the 107th Naval Construction battalion, which built a ramp from the shore to the reef. In November 1944, the 50th Naval Construction Battalion commenced a major project to build permanent harbor facilities that could berth up to eight
Liberty ships at a time. The new harbor consisted of a south bulkhead, a quay wall, and two piers parallel to the cargo ship bulkhead and connected to it by an causeway. A breakwater was built upon the existing reef consisting of 120 circular sheet piling cells that were in diameter and filled with coral. The task of dredging a deep channel and deep berths was undertaken by the 31st Naval Construction Battalion, which was part of
Service Squadron 12. Dredging was completed on 20 January 1945, and the harbor works were completed on 6 March.
Other facilities The Japanese roads on the island were too narrow for heavy construction vehicles, had inadequate drainage, and lacked
shoulders. They were resurfaced with of pit coral, and drainage and shoulders were added. Due to the shape of the island and the grid layout of its roads bearing a resemblance to those of
Manhattan, the streets were named after those of New York City. The Japanese town of Sunharon became known as the Village because its location corresponded to that of
Greenwich Village, and the open area between North and West Fields became known as
Central Park. Another of new roads were built, with roadways and shoulders. Accommodation was constructed for 12,000 Seabees, 13,000 other navy personnel, and 21,500 Army personnel. A 100-bed tent hospital was erected in September 1944. The 600-bed Navy Base Hospital 19 opened in December. It was subsequently upgraded to a 1,000-bed hospital. The Army's 600-bed 374th Station Hospital opened in March 1945, and the 1,000-bed 48th Station Hospital in June on the camp site of the 135th Naval Construction Battalion after it moved to Okinawa. In August, the 4,000-bed 821st Hospital Center on the South Plateau was under nearing completion. The 18th Naval Construction Battalion handled construction of the Marine Corps's 7th Field Depot, which was subsequently converted to a quartermaster depot for the Army garrison. When complete, it consisted of three camp sites with of warehouse storage, of open air storage and of refrigerated storage. The naval supply depot had of warehouse storage. Construction of an ammunition storage dump commenced in September 1944. On completion in February 1945, it had 254 revetments with coral surfaces and of roads. Work on a bomb dump with 468 revetments commenced in January 1945, and was completed by the middle of the year. To support
Operation Starvation, the aerial mining campaign against Japan, an aerial mining depot was built with Quonset hut magazines surrounded by revetments. Tinian's porous coral soil provides good drainage, so there are no rivers or creeks on the island, and only one small fresh-water lake, Hagoi (whose name means "lake" in the
Chamorro language). However, the annual rainfall is more than , so the Japanese developed a system of wells and reservoirs.This was rehabilitated by the Seabees, who sunk 17 new wells. Initially water was rationed to per man per day, but eventually a water supply system was developed with a capacity of per day, and water rationing was no longer required. ==Operations==