Research

Despite precautions taken by the operators of maintenance vehicles, insufficient visibility of winter operations vehicles cause many collisions in the United States. Numerous methods have been developed to enhance the visibility of winter operations vehicles. Although the visibility of winter operations vehicles has enhanced through these methods, the consistency in the implementation of the methods for enhancing their visibility is critical to avoid collisions. The inconsistencies in the implementation of the methods confuse the public who are traveling in winter conditions when visibility is low. The confusion leads to a delay in perception time and response time of the drivers and eventually, leads to rear-end collisions with the winter operations vehicles. Although anecdotal evidence shows the inconsistency as a barrier to the successful implementation of visibility methods, the extent of the inconsistencies is not known.

For safer winter operations, it is critical to investigate the differences, similarities, and challenges associated with the existing methods for enhancing the visibility of winter operations. The objective of this research is to investigate the differences, similarities, and challenges associated with these methods. A survey questionnaire was designed to accomplish this objective. The questionnaire was distributed among all the 50 states of the U.S. The survey questionnaire was also distributed among 25 Texas Department of Transportation (TxDOT) districts to sample the extent of such inconsistencies within a state.

In this study, the current state of knowledge and practice are captured and integrated to present the striking dissimilarities within the methods for visibility of winter operations in various states in the U.S. Even within one state (i.e., Texas), considerable differences were identified. The study also shows that some states are utilizing successful methods of visibility, like elevated warning lights and heated lenses, which are not being used by other states. On the other hand, maintenance officials consistently face challenges regarding the cleaning of their vehicles after each winter operation, which delays the time between operations and uses additional manpower. The findings of this study would help the transportation agencies implement consistent methods for enhancing the visibility of winter operations vehicles.

Rectangular hollow sections (RHS) have been used in the construction of steel structures for many years. They are commercially produced in various lengths and thicknesses to suit to any structural requirement. Like all steels structures however, RHS is particularly vulnerable to fire. Fire protection layer such as Intumescent paint, Vermiculite and Refractory Ceramic Fibre (RCF) are available to insulate RHS from contact with fire in case of accidents. Material studies has been conducted regarding the effectiveness of the fire protection layers in various research papers. In the present study, a finite elementinvestigation has been conducted to simulate the behavior of RHS with and without theprotective layers. A three dimensional finite element model for Rectangular Hollow Section using shell element has been developed. Application of fire protection layers were conducted by adding an additional layer of shell element. Both material and geometric nonlinearities are incorporated in the model. The developed finite element model has been applied to simulate experimental studies done by past researchers and it has been found that good agreement exists between present analysis and past experimental results, which establishes the acceptability and validity of the present finite element model to carry out further investigation. The simulation of real life fire scenarios then showed that intumescent paint provides good insulation for about 60 minutes before failing due to loss of coating as charred ash. Vermiculite and Refractory Ceramic Fibres show prolonged fire protection, however the binder between these layers and RHS is the cause of failure, resulting inexposed RHS and collapse of structure after around 60 minutes.