Lift axles in ready mix trucking

Lift axles on single-unit commercial vehicles, referred to as Specialized Hauling Vehicles (SHVs) are being used today by various industries, allowing for heavier truck loads and compliance with state / federal laws. Certain industries – such as aggregate and hot mix, refuse, and ready mix – operate SHVs more frequently than other industries. The purpose of this Thesis research is to analyze the ready mix industry and understand the benefits and dis-benefits of operating SHVs as part of a company’s truck fleet. In addition, the author seeks to gain an understanding of differences in state and federal laws, codes, and regulations regarding SHVs. Further, the research aims to understand the reasons ready mix companies choose to operate (or not operate) lift axles. To achieve the objectives of this research, the author conducted a literature review, performed statistical analysis on ready mix truck sales data, studied SHV operation data in Texas, summarized lift axle regulations in the United States, analyzed previously conducted trade group surveys, and administered a survey to determine patterns and gain information about lift axle use in the ready mix industry, with a focus on Texas and nine other peer states. Sales data showed that the ten states in focus had an overall proportion of 32% of SHVs in the ready mix industry. In regulations, four of the states studied do not have specific lift axle laws. In these states, regulations applicable to lift axle weights are those applicable to general commercial vehicles based on the Federal Bridge Formula B, and state axle weight exemptions, if they exist. Some states have regulations controlling where the lift axle control mechanisms must be placed, while two states have regulations allowing trucks to lift axles during turns. Analyzed surveys showed an SHV proportion in the ready mix industry around 60-70%. The author’s survey corroborated this, with 64% of the responses from companies that operate SHVs. Analyzed survey data showed a growth trend in SHV configurations of about 1% per year. Reponses to the author’s survey responses suggest companies select lift axles for the following reasons: to carry more weight and to be legal on highways with load ratings based on the Federal Bridge Formula. All stakeholder contacts mentioned an upward trend in lift axle usage which was corroborated, although to different degrees, in the previously performed data collection efforts in Texas, analyzed surveys, and the author-administered survey