This report includes an updated set of recommended MR levels for traffic signs based on recent developments in vehicle headlamps, vehicle types/sizes, nighttime driver needs, and newer sheeting materials. The updated MR levels are also based on more robust computer modeling of retroreflective sheeting performance.

TRB’s National Cooperative Highway Research Program (NCHRP) Synthesis 431: Practices to Manage Traffic Sign Retroreflectivity includes examples of practices that illustrate how different types of transportation agencies might meet federal retroreflectivity requirements for traffic signs.

In this study, the Pavement Marking Visibility Module of the Tarvip model was validated by comparing field data from various studies to prediction results under similar conditions from Tarvip. Next, a comprehensive survey on the factors that affect pavement marking visibility and minimum RL levels was performed, with key factors identified, including pavement marking configuration, pavement surface type, vehicle speed, vehicle type, and presence of RRPMs. From these key factors, a methodology of using Tarvip to do a sensitivity analysis on factors modeled in it was developed. The plan was executed, and resulting RL values under typical conditions on United States roadways formed the basis of new recommendations. Finally, limitations of the recommendations were analyzed, and a plan for future research was presented. This study was aimed at completing the research to develop and scrutinize minimum levels for pavement marking retroreflectivity to meet nighttime driving needs. A previous study carried out in the 1990s was based on the CARVE model developed at Ohio University and resulted in a table of minimum levels of pavement marking retroreflectiviy values. Since then, a newer, more powerful analytical tool, Tarvip, which was developed at the Operator Performance Lab of the University of Iowa, overcomes a lot of limitations of the CARVE model and uses updated data that reflect the current states of vehicles and roadways in the United States.

NCHRP synthesis 371 explores the state of the practice for managing transportation infrastructure assets other than pavements and bridges, and documents gaps in knowledge and areas in need of potential further study.

The main objectives of 2013 International Conference on Transportation (ICTR2013) are to bring together representatives of transportation engineering , of various institutions, universities, industry and professional associations, to debate and exchange experience on important conference topics. Another main objective of ICTR2013 consists of providing a good networking opportunity to all these groups. The ICTR2013 became a major conference to exchang e new ideas of transportation in Asia researchers and provide a form to present their new results in transportation engineering, vehicle operation engineering, transportation planning, traffic information engineering and control, pavement and bridge engin eering and other related topics. ICTR2013 is held in Xianning, China from December 4 to 6, 2013 sponsored by Shanghai Jiaotong University and DES t ech Publishing Inc. In the first edition of the ICTR2013 189 papers were submitted, 69 of which were accepted . In addition to the authors that were present at the conference, researchers from universities and institutions also send papers. The organizing committee hopes this conference proceedings will provide readers a broad overview of the latest advances on tr ansportation. The organizing committee also believes this conference proceedings would be a good reference for academic researchers and industrial professionals in these fields. The ICTR2013 organizing committee would like to express our sincere appreciat ions to all authors for their contributions to this conference. We would like to extend our thanks to all the referees for their constructive comments on all papers. Finally, we would like to thank DES t ech publishing Inc . for producing this conference proc eeding. We hope you will have a unique, rewarding and enjoyable weekend at ICTR2013 in Xianning, China.