Investing in research and development work to design a new SST can be considered as an effort to push the speed limit of air transport. Generally, other than an urge for new technological achievement, the major driving force for such an effort is competitive pressure from other modes of transport. Competition between different service providers within a mode of transport does not typically lead to such technological investments to increase the speed. Instead, the service providers prefer to compete in service quality and cost. An example of this phenomenon is high-speed rail. The speed limit of rail transport had been pushed so hard to enable it to effectively compete with road and air transport. But this achievement was not done for different rail operating companies to compete among themselves. This phenomenon also reduces the airline desirability of SSTs, because, for very long distance transportation (a couple of thousand kilometers), competition between different modes of transport is rather like a single-horse race: air transport does not have a significant competitor. The only competition is between the airline companies, and they would rather pay moderately to reduce cost and increase service quality than pay much more for a speed increase. Also, for-profit companies generally prefer low risk businesses plans with high probabilities of appreciable profit, but an expensive leading-edge technological research and development program is a high-risk enterprise, as it is possible that the program will fail for unforeseeable technical reasons or will meet cost overruns so great as to force the company, due to financial resource limits, to abandon the effort before it yields any marketable SST technology, causing potentially all investment to be lost.