Scheduling commercial advertisements for television

The problem of scheduling the commercial advertisements in the television industry is investigated. Each advertiser client demands that the multiple airings of the same brand advertisement should be as spaced as possible over a given time period. Moreover, audience rating requests have to be taken into account in the scheduling. This is the first time this hard decision problem is dealt with in the literature. We design two mixed integer linear programming (MILP) models. Two constructive heuristics, local search procedures and simulated annealing (SA) approaches are also proposed. Extensive computational experiments, using several instances of various sizes, are performed. The results show that the proposed MILP model which represents the problem as a network flow obtains a larger number of optimal solutions and the best non-exact procedure is the one that uses SA

(Dt,C) Optimal run orders.

Cost considerations have rarely been taken into account in optimum design theory. A few authors consider measurement costs, i.e. the costs associated with a particular factor level combination. A second cost approach results from the fact that it is often expensive to change factor levels from one observation to another. We refer to these costs as transition costs. In view of cost minimization, one should minimize the number of factor level changes. However, there is a substantial likelihood that there is some time order dependence in the results. Consequently, when considering both time order dependence and transition costs, an optimal ordering is not easy to find. There is precious little in the literature on how to select good time order sequences for arbitrary design problems and up to now, no thorough analysis of both costs is found in the literature. For arbitrary design problems, our proposed design algorithm incorporates cost considerations in optimum design construction and enables one to compute cost-efficient run orders that are optimally balanced for time trends. The results show that cost considerations in the construction of trend-resistant run orders entail considerable reductions in the total cost of an experiment and imply a large increase in the amount of information per unit cost.Optimal; Run orders;

Evaluation Of Milwaukee B And Synchronized As New Service Interchange Designs

These days, alternative interchanges are attracting the attention of transportation agencies and designers more than ever. Most of the existing interchanges in the U.S were built in the 1950s and 1960s when traffic volume was much lower, and the type of vehicles and driving habits were completely different. Moreover, the knowledge of highway design and safety is more developed now, and this provides an appropriate situation to increase the efficiency of interchanges regarding traffic operation and safety using alternative interchanges. This research evaluated the performance of two proposed service interchange designs—the synchronized design which is related to a superstreet intersection and the Milwaukee B design that is related to a parclo B design--as possible substitutes where existing interchanges are failing. Over 1700 simulation tests modeled the traffic operation, pedestrian performance, and safety of six different interchanges (two new and four existing interchanges) in different conditions of traffic volume, traffic distribution, left/right turning volume ratios, and heavy vehicle percentage. Then, a cost estimation and validation procedure were also conducted to complete the analysis. Overall, the Milwaukee B showed the best traffic operation among all the interchanges. The synchronized interchange looks promising as a substitute for a diamond interchange with dominant through traffic. The synchronized and diverging diamond interchanges (DDI) showed almost the same results while handling moderate levels of turning volume; however, the synchronized performed better than the DDI in low turning volumes while the DDI can be a better choice in high turning ratios. Regarding the safety, the DDI and Milwaukee B were the safest designs based on observed conflicting interactions in the simulation models; however, the DDI did not seem as reliable from the viewpoint of unusual maneuvers and wrong way movements. The new synchronized interchange, the parclo B, and the Milwaukee A (an existing interchange in Milwaukee, WI) showed the same rate of conflicts. The synchronized interchange may be advantageous because it was estimated to reduce the severity of crashes due to fewer crossing conflicts, a lower speed of conflicts, and a higher time to collision. The results of the pedestrian analysis indicated that a relatively safe condition is expected for pedestrians in the proposed new designs in comparison to the existing interchanges. The DDI, one of the most popular alternative interchanges, showed the worst performance in all the aspects of the pedestrian analysis

Safety Evaluation of Innovative Intersection Designs: Diverging Diamond Interchanges and Displaced Left-turn Intersections

Diverging diamond interchanges (DDIs) and Displaced left-turn intersections (DLTs) are designed to enhance the operational performance of conventional intersections that are congested due to heavy left-turn traffic volumes. Since drivers are not familiar with these types of intersections, there is a need to evaluate their safety performance to validate their effect, and to estimate reliable and representative Crash Modification Factors (CMFs). The safety evaluation was conducted based on three common safety assessment methods, which are before-and-after study with comparison group, Empirical Bayes before-and-after method, and cross-sectional analysis. Furthermore, since DLTs showed poor safety performance, the study also investigated the operational performance of DLTs using a general linear model describing the relationship between traffic delay and other operational and geometric characteristics based on high-resolution traffic data. The DDI analysis included a sample size of 80 DDIs and 240 conventional diamond interchanges in 24 states, while the DLT analysis included 13 DLTs and 26 conventional intersections in 4 states. The analysis results indicated that converting conventional diamond interchanges to diverging diamond interchanges could significantly decrease the total, fatal-and-injury, rear-end and angle/left-turn crashes by 26%, 49%, 18%, and 68%, respectively. On the other hand, converting conventional intersections to displaced left-turn intersections could significantly increase the total number of crashes as well injury crashes and some other crash types (i.e., single vehicle, angle). However, the operational analysis implied that they have the potential to reduce the delay at intersections by 3.567 sec/veh. Consequently, the study quantified the costs and benefits associated with implementing DLTs. The results showed that this alternative design could provide much benefits in terms of its operational performance. However, its poor safety performance could result in losses much higher than its benefits. The study concludes that DDIs could significantly decrease crash frequency, while DLTs could not provide safety benefits. However, DLTs might be more efficient for operational performance. It is recommended that appropriate safety countermeasures should be developed and implemented to enhance traffic safety at DLTs

Evaluating Pedestrian Service of the New Super Diverging Diamond Interchange on Three Case Study Sites in Denver, Colorado

Ensuring safe and comfortable conditions for pedestrians necessitates specific strategies at intersections and service interchanges where traffic and pedestrians interact in complex ways with other modes of transportation. This study aims to investigate pedestrian performance at the new Super Diverging Diamond Interchange (Super DDI) using real-world locations (i.e., I-225 and Mississippi Ave, I-25 and 120th Ave, and I-25 and Hampden Ave in Denver, Colorado). Three alternative designs, typical DDI, and two versions of Super DDI were considered to make a reasonable comparison with the existing Conventional Diamond Interchange (CDI). A comprehensive series of simulation models (192 scenarios with 960 runs) were tested using VISSIM and Synchro to analyze pedestrian operation (travel time, number of stops, and waiting time) in various traffic and pedestrian distributions. As one of the primary contributions in this paper, pedestrian safety was evaluated based on a surrogate performance measure called design flag, introduced by the new National Cooperative Highway Research Program (NCHRP-948) guideline. The results indicated that the proposed new Super DDI designs are relatively safe when compared with CDI and DDI. For example, a pedestrian analysis of one of the most popular alternative interchanges, DDI, showed potential for unsafe pedestrian conditions in all aspects

Performance of Alternative Diamond Interchange Forms: Volume 1—Research Report

Service interchanges connect freeways to arterial roads and are the backbone of the U.S. road network. Improving the operations of service interchanges is possible by applying one of several new solutions: diverging diamond, single point interchanges, and double or single roundabout diamonds. VISSIM was used to perform 13,500 experiments to simulate the traffic performance of the studied alternative interchanges during a typical day for a wide range of geometry and traffic scenarios. Five performance measures were investigated: daily-average delay, level of service of critical movement, daily-average number of stops, longest off-ramp queue, and longest crossing road queue. The obtained daily-average delays at the alternative interchanges were consistent with expectations. Roundabouts had the highest average delay while single-point interchanges had the lowest average delays. Roundabouts exhibited the lowest numbers of stops among all the alternatives in the low traffic range up to non-freeway 30,000 veh/day. Diverging diamonds tended to have the shortest and roundabouts tended to have the longest queues on their off-ramps. Overall, single-point interchanges had the shortest queues among all the alternatives. The study developed guidelines for early stage screening of alternative diamond. The guidelines exhibit performance measures for 25 traffic and geometric scenarios and a wide range of traffic volumes. The guidelines provide a fair comparison procedure for alternative diamond interchanges in the preliminary planning and conceptual design stages

Trend-resistant and cost-efficient cross-over designs for mixed models.

A mixed model approach is used to construct optimal cross-over designs. In a cross-over experiment the same subject is tested at different points in time. Consider as an example an experiment to investigate the influence of physical attributes of the work environment such as luminance, ambient temperature and relative humidity on human performance of acceptance inspection in quality assurance. In a mixed model context, the subject effects are assumed to be independent and normally distributed. Besides the induction of correlated observations within the same inspector, the mixed model approach also enables one to specify the covariance structure of the inspection data. Here, several covariance structures are considered either depending on the time variable or not. Unfortunately, a serious drawback of the inspection experiment is that the results may be influenced by an unknown time trend because of inspector fatigue due to monotony of the inspection task. In other circumstances, time trend effects can be caused by learning effects of the test subjects in behavioural and life sciences, heating or aging of material in prototype experiments, etc. An algorithm is presented to construct cross-over designs that are optimally balanced for time trend effects. The costs for using the subjects and for altering the factor levels between consecutive observations can also be taken into account. A number of examples illustrate utility of the outlined design methodology.Optimal; Models; Model;

Tradeoffs among Free-flow Speed, Capacity, Cost, and Environmental Footprint in Highway Design

This paper investigates differentiated design standards as a source of capacity additions that are more affordable and have smaller aesthetic and environmental impacts than expressways. We consider several tradeoffs, including narrow versus wide lanes and shoulders on an expressway of a given total width, and high-speed expressway versus lower-speed arterial. We quantify the situations in which off-peak traffic is sufficiently great to make it worthwhile to spend more on construction, or to give up some capacity, in order to provide very high off-peak speeds even if peak speeds are limited by congestion. We also consider the implications of differing accident rates. The results support expanding the range of highway designs that are considered when adding capacity to ameliorate urban road congestion.Highway design; Capacity; Free-flow speed; Parkway

Optimal designs for rating-based conjoint experiments.

The scope of conjoint experiments on which we focus embraces those experiments in which each of the respondents receives a different set of profiles to rate. Carefully designing these experiments involves determining how many and which profiles each respondent has to rate and how many respondents are needed. To that end, the set of profiles offered to a respondent is viewed as a separate block in the design and a respondent effect is incorporated in the model, representing the fact that profile ratings from the same respondent are correlated. Optimal conjoint designs are then obtained by means of an adapted version of the algorithm of Goos and Vandebroek (2004). For various instances, we compute the optimal conjoint designs and provide some practical recommendations.Conjoint analysis; D-Optimality; Design; Model; Optimal; Optimal block design; Rating-based conjoint experiments; Recommendations;