California Department of Transportation

About: California Department of Transportation is a government organization based out in Sacramento, California, United States. It is known for research contribution in the topics: Poison control & Seismic analysis. The organization has 308 authors who have published 389 publications receiving 12623 citations. The organization is also known as: Caltrans & Bureau of Highways.

Development of the Trenchless Installations for Underground Structures in Highway Systems

Abstract: There are many underground structures, such as culverts, tunnels and vehicle undercrossing in transportation systems throughout the world. These structures are used to convey water, wildlife, fish, pedestrians and vehicles. Their roles are just as important as surface structures, such as bridges. Cut-and-cover, immersing and trenchless installations are the three major methods to construct underground structures. For an installation of buried structure, the specific method should be chosen based on the factors such as geotechnical properties in subgrade, environment impact, cost and the degree of disturbance to the highway traffic above it. Currently, it is becoming more popular to use trenchless installations including tunneling methods for new structures and trenchless replacement method for existing structures. Comparing to cut-and-cover method, trenchless installations provide much less impact to the roadway traffic and the environment. The trenchless installation method can be used to install a utility line with a small cross-sectional size of 4 inches in diameter for hundreds of feet long as well as a large facility with a width of 51 feet for 5.6 miles, as in the case of Chongming Tunnel across Yangtze River in Shanghai. Trenchless technology (TT) consists of a wide range of methods, materials, and equipment for installing new or rehabilitating existing underground structures. Frequently used tunneling methods include Pipe Jacking for pipes or concrete boxes, Horizontal Direct Drilling (HDD) for pipes, Auger Boring using steel casing (SC), Pipe Ramming using SC, Micro-tunneling, Tunneling by Tunneling Boring Machin (TBM) and so on. On the other hand, Cured-In-Place-Pipe (CIPP) is an effective method to replace existing pipes in place, and Slipling is used to rehabilitate existing pipes. Major trenchless installation methods, size limits and approximate maximum lengths are summarized in Table 1. *Corresponding author: Carl M. Duan, Senior Bridge Engineer and Specialist of Culverts and Underground Structures, California Department of Transportation, USA. Received Date: September 09, 2019

Accurate, Timely, Reliable: A High Standard and Elusive Goal for Traveler Information Data Quality

Abstract: In this paper, we demonstrate the difficulty of conducting spatio-temporal data quality control for sensor data. Our motivation is the provision of quality traveler information by departments of transportation. We show that assessment of accuracy of air temperature requires robust methods that go beyond the identification of outliers and inliers to mitigate the impact of bad data and bad metadata. We give a representative approach and demonstrate the challenges of assessment, particularly in the presence of incorrect data quality labels and the absence of ground truth for this air temperature data. Our approach is model-based and can be used to estimate not only outliers versus inliers, but also degree of outlyingness. It can not only be used to identify bad data in general as well as bad metadata. We evaluate our approach against other methods that use interpolation to model the data. We use an Area Under the ROC (AUROC) analysis to compare methods when data quality labels are provided. We use mean-squared-error and t-tests to compare methods both when labels are provided and when not. We measure scalability using computation time.

Comments on Interrelations between Urban Land-Use and Transportation

Abstract: A city can be thought of as a social and economical system with significant complexity, and with various activities taking place within the system. Between the activities (as the demand side) and the land-use/transportation (as the supply side), there exist extremely sophisticated interrelations. A better understanding of these interrelations for utilizing the underlying mechanism to develop urban land-use and transportation systems in a scientific and reasonable way is one of the basic research subjects in both urban planning and transportation fields. Starting with an analysis of activities, this paper reveals that activities are the demand source of land-use and transportation, and then discusses the interrelations between the two supply subsystems, i.e. land-use and transportation. The paper further points out that emphasizing on interactions between land-use and transportation in achieving equilibrium in demand and supply between activities and land-use/transportation is the fundamental principle not only for a healthy and sustainable urban development, but for a sound planning of urban land-use and transportation as well.

A Discussion on the Current MUTCD Standards on Traffic Control Signals for Freeway Entrance Ramps

Abstract: In Section 4I.02 of the newly published Manual on Uniform Traffic Control Devices (MUTCD), standards were specified for the placement of signal heads for traffic control signals at freeway entrance ramps, or ramp meters. For simultaneous operations, i.e. when ramp control signals are operated such that green signal indications are always displayed simultaneously to all of the lanes on the ramp, a minimum of two signal faces per ramp shall face entering traffic. For staggered operations, i.e. the ramp control signal are operated such that green signal indications are not always displayed simultaneously to all of the lanes on the ramp, one signal face shall be provided over the approximate center of each separately-controlled lane. Based on a nation-wide survey, it was realized that the two standards did not fully reflect the state-of-the-practice with respect to ramp metering operations. Due to the lack of significant conflicting movements at ramp meters, for any on-ramp lane, a minimum of one overhead mounted, or one upper and one lower roadside-mounted signal face is sufficient to control the metering operations. The minimum necessary number of signal faces changes according to the total number of lanes, how the signal faces are mounted (overhead or roadside mounting), and how the meters are operated (simultaneous or staggered). Suggestions are made to revise the two standards to better reflect the current nation-wide practices, and better consider the specific operational needs for ramp meters.