On Lincoln's birthday, 1962, an LOD team visited Paradise, Kentucky, to watch a Bucyrus-Erie 2,700-metric-ton crawler-shovel in action. Albert Zeiler's report compared the crawler favorably to LC-34's service structure. The work platform, stabilized by hydraulic cylinders at the four corners, varied no more than one-half degree from level. Nearby, Bucyrus-Erie was constructing for the Peabody Coal Company a larger crawler-shovel which would have a load-bearing capacity in excess of the expected weight of the Saturn C-5 and its support equipment. Although minimum speed for the existing crawler was only 6.1 meters per minute, more speed could be built into the new model. Impressed with the crawler's potential, the LOD representatives asked their hosts to propose a study program for LC-39.27
Bucyrus-Erie began such a study one month later. An LOD phone call on 23 March requested preliminary information for Petrone's congressional briefing that afternoon. Thomas Learmont, Bucyrus-Erie's chief design engineer, provided tentative estimates: the crawler, jacks, hydraulic system, and steering mechanisms would cost $3,650,000, the umbilical tower $1,500,000, the box structure (launch platform) $800,000. The crawler figure reflected the cost of Bucyrus-Erie's new model with few changes. Later Bucyrus-Erie incorporated a redundant power system and a more sensitive leveling mechanism, raising estimates an additional million dollars. Although the crawler's reliability and flexibility were attractive the cost was a major disadvantage. LC-39 plans called for five launcher-transporters, putting the price of the crawler units at nearly $25 million. In early April, Buchanan suggested separating the launcher from its transporter and building only two crawlers. The proposal would increase total launcher-transporter weight (the separate crawler would require a heavy platform), but the cost savings more than compensated. After Buchanan's idea won approval, LOD supplemented Bucyrus-Erie's contract to include a "separate crawler" investigation.28
By May the crawler was scoring the highest marks of the three transfer proposals. On the 10th Poppel, Buchanan, and Duren inspected barge tests at the model basin and reviewed the adverse findings from the wind tunnel. The following day Bucyrus-Erie's final presentation was well received by NASA personnel. The crawler would go 1.6 kilometers per hour under load. Its turning radius was 152 meters. The hydraulic leveling system would keep the platform within 25 centimeters of the horizontal when moving on a 5% grade. The Jacksonville engineering firm of Reynolds, Smith, and Hills reported crawlerway costs per mile of $447,000 on high ground and $1,200,000 across marsh. The latter figure included the cost of removing 6 meters of silt so that a firm roadway could be constructed. The estimate was close to the eventual cost of $7.5 million for ten kilometers of crawlerway, On 15 May, Harvey Pierce summarized Connell's rail study. Although the new railbed appeared sound, it was unproven and twice the cost of a crawlerway. Perhaps more important, the switching arrangements looked like trouble to operations personnel.29
The crawler received a further boost from a 1 June Corps of Engineers report. During a three-week study, the Jacksonville office focused on Merritt Island's ability to support the different transporters. Rail fared the worst.
As a result of the nonhomogeneity of the foundation materials, differential settlement is inevitable along any long embankment. The effect of such settlement would be most detrimental to any system using rails or concrete slabs. Flexible pavements would be less affected and the effect on canal design would be negligible.30A barge transporter would entail high construction costs for a launch basin and docking facilities at the vertical assembly building; the Corps of Engineers estimated $20,000,000 for the launch basin alone. The crawler presented no serious problems.
The decision to use the crawler came at an LC-39 conference on 12 - 13 June. Representatives from NASA Headquarters, the Manned Spacecraft Center, Marshall divisions, and private industry joined LOD at the Cape meeting. The launcher-transporter's crucial role placed it first on the agenda. After reviewing LOD's search, Donald Buchanan compared the three major contenders. Although the barge concept offered the best growth potential, there were unresolved design problems with propulsion, steering, platform stability, and placement at the Launch pad. Buchanan noted, "If meeting a tight schedule has any bearing on the choice of modes, it would be difficult to assign a low enough value to the barge to illustrate the situation as it now stands."31 The barge's operational shortcomings included a vulnerability to blast and a slow reaction time (evacuating the rocket in an emergency from the launch pad). While both the rail and crawler systems were within the state of the art, the latter enjoyed advantages of cost and flexibility. Buchanan's crawler recommendation met no serious objections.32