Travel time estimation from loop measurements has attracted extensive research in the last decade, resulting in numerous methodologies. Among these, those that rely on spot speed measurements at detector sites to obtain travel time estimation on the target stretch are the most intuitive. The key issue concerning these methods is the spatial generalization of point measurements over a freeway link. This paper shows that all speed interpolation methods that omit traffic dynamics and queue evolution do not contribute to better travel time estimations. All methods are inaccurate in congested and transition conditions, and the claimed relative benefits using various speed interpolation methods result from context-specific experiments. Therefore, these methods should be carefully used and not taken as perfect. Lacking a better approach, it is recommended to avoid overcomplicated mathematical interpolations and focus efforts on intelligent smoothing of the noisy loop detector data, reducing the fluctuations of short time interval aggregations while maintaining the immediacy of the measurements.

Autonomous vehicles promise to revolutionize the automobile market, although their implementation could take several decades in which both types of cars will coexist on the streets. We formulate a model for a circular city based on continuous approximations, considering demand surfaces over the city. Numerical results from our model predict direct and indirect effects of connected and autonomous vehicles. Direct effects will be positive for our cities: (a) less street supply is needed to accommodate the traffic; (b) congestion levels decrease: travel costs may decrease by 30%. Some indirect effects will counterbalance these positive effects: (c) a decrease of 20% in the value of travel time can reduce the total cost by a third; (d) induced demand could be as high as 50%, bringing equivalent total costs in the future scenario; (e) the vehicle-kilometers traveled could also affect the future scenario; and (f) increases in city size and urban sprawl. As a conclusion, the implementation of autonomous vehicles could be neutral for the cities regarding travel time costs. City planning agencies still have to promote complementary modes such as active mobility (walking and bicycle), transit (public transportation), and shared mobility (shared autonomous vehicles and mobility as a service).

This paper shows that the precision of a freeway travel-time information system, in a real-time context, is not related solely to the accuracy of the measurement. Immediacy in reporting the information and forecasting capabilities play a role. Therefore, focusing only on the accuracy of the travel-time measurement is a myopic approach, which can lead to counterintuitive results. Specifically, it is claimed that, using travel times estimated with the traditional spot-speed midpoint algorithm, the performance of the real-time information system when evolving traffic conditions prevail is better than using much more accurate directly measured travel times (MTTs). Guidelines for an adequate configuration of the common parameters of the system are provided. In addition, real-time context enhancements for travel-time estimation methods based on punctual speed measurements are proposed. These are addressed by taking into account an easy and practical implementation. They have been proven to work well in an empirical application on a Spanish freeway.

This paper shows how the geometric concepts examined in the first paper perform for baggage operations, recognizing that passengers and bags travel different distances through the airport. The paper shows that the most effective geometry (minimizing total passenger walking plus baggage travel costs) can be selected by focusing on passenger walking alone, provided that one first calculates an equivalent percentage of transfers with a simple formula. The paper also introduces a “sun” terminal concept, consisting of a circular concourse (open or closed) with both gates and piers (possibly with branches), which generalizes the geometries of part one to some advantage. Finally, the paper introduces and compares the results of two techniques that are useful for more refined analyses. The first of these, calculus of variations, was used to develop simple approximate formulas for the optimal shape of parallel‐pier terminals. The second technique, simulated annealing, does not lead to formulas but can be used without simplifications; e.g., to refine a preliminary design with the aid of a computer, recognizing real‐world complications.