Peer state assessment of TxDOT maintenance program and practices, part II : test section survey findings and recommendations

This paper presents a road survey as part of a workshop conducted by the Texas Department of Transportation (TxDOT) to evaluate and improve the maintenance practices of the Texas highway system. Directors of maintenance from six peer states (California, Kansas, Georgia, Missouri, North Carolina, and Washington) were invited to this 3-day workshop. One of the important parts of this workshop was a Maintenance Test Section Survey (MTSS) to evaluate a number of pre-selected one-mile roadway sections. The workshop schedule allowed half a day to conduct the field survey and 34 sections were evaluated. Each of the evaluators was given a booklet and asked to rate the selected road sections. The goals of the MTSS were to: 1. Assess the threshold level at which maintenance activities are required as perceived by the evaluators from the peer states; 2. Assess the threshold level at which maintenance activities are required as perceived by evaluators from other TxDOT districts; and 3. Perform a pilot evaluation of the MTSS concept. This paper summarizes the information obtained from survey and discusses the major findings based on a statistical analysis of the data and comments from the survey participants.

Peer state assessment of TxDOT maintenance program and practices, part I : workshop findings and recommendations

To assess and improve their practices, and thus ensure the future excellence of the Texas highway system, the Texas Department of Transportation (TxDOT) sought a forum in which experts from other State Departments of Transportation could evaluate the TxDOT maintenance program and practices based on their expertise. To meet this need, a Peer State Review of TxDOT Maintenance Practices project was organized and conducted by the Center for Transportation Research (CTR) at The University of Texas at Austin. CTR researchers, along with TxDOT staff, conducted a workshop to present TxDOT’s maintenance practices to the visiting peer reviewers and invite their feedback. Directors of maintenance from six different states—California, Kansas, Georgia, Missouri, North Carolina, and Washington—participated in the workshop. CTR and TxDOT worked together to design a questionnaire with 15 key questions to capture the peers’ opinions on maintenance program and practices. This paper compiles and summarizes this information. The examination results suggested that TxDOT should use a more state-wide approach to funding and planning, in addition to funding and planning for each district separately. Additionally, the peers recommended that criteria such as condition and level of service of the roadways be given greater weight in the funding allocation than lane miles or vehicle miles traveled (VMT). The Peer Reviewers also determined that TxDOT maintenance employee experience and communications were strong assets. Additional strengths included the willingness of TxDOT to invite peer reviews of their practices and a willingness to consider opportunities for improvement.

Time-Dependent Density Functional Molecular Orbital and Excited State Calculations on Bis(porphyrinyl)butadiynes in the Monocationic, Neutral, Monoanionic, and Dianionic Oxidation States

We report a theoretical study of the multiple oxidation states (1+, 0, 1−, and 2−) of a meso,meso-linked diporphyrin, namely bis[10,15,20-triphenylporphyrinatozinc(II)-5-yl]butadiyne (4), using Time-Dependent Density Functional Theory (TDDFT). The origin of electronic transitions of singlet excited states is discussed in comparison to experimental spectra for the corresponding oxidation states of the close analogue bis{10,15,20-tris[3‘,5‘-di-tert-butylphenyl]porphyrinatozinc(II)-5-yl}butadiyne (3). The latter were measured in previous work under in situ spectroelectrochemical conditions. Excitation energies and orbital compositions of the excited states were obtained for these large delocalized aromatic radicals, which are unique examples of organic mixed-valence systems. The radical cations and anions of butadiyne-bridged diporphyrins such as 3 display characteristic electronic absorption bands in the near-IR region, which have been successfully predicted with use of these computational methods. The radicals are clearly of the “fully delocalized” or Class III type. The key spectral features of the neutral and dianionic states were also reproduced, although due to the large size of these molecules, quantitative agreement of energies with observations is not as good in the blue end of the visible region. The TDDFT calculations are largely in accord with a previous empirical model for the spectra, which was based simplistically on one-electron transitions among the eight key frontier orbitals of the C4 (1,4-butadiyne) linked diporphyrins.