This licentiate thesis consists of an introduction (‘kappa’) and three papers discussing various aspects of time as a commodity and the practice of valuing travel time. The first paper is an analysis of the properties of time as an economic resource taking into account literature on behavior with regard to time. The intent is to provide better understanding of the underlying assumption of transferability between time and money in the context of transportation. The second paper builds on the analysis in the first paper combined with the findings of a study of commuters travel experiences during disruptions in the train traffic on the Øresund strait between Sweden and Denmark. It contrasts the theoretical account of value of travel time with the experiences reported by commuters and argues that the view of travel time as strictly a disutility can be limiting from a planning perspective. Instead, it is argued that an alternative approach can be to make travel time ‘plannable’, meaning viewing travel time as time travellers can plan to spend in a certain way at a certain time. The third paper argues that the diversity of possible mobility solutions based on self-driving vehicles has been somewhat overlooked in the current literature on value of travel time. Thus, the complexity of valuing travel time for self-driving vehicles has not been fully addressed. The paper consists of a morphological analysis of the parameters that might impact value of travel time for self-driving vehicles and a deeper analysis of five plausible self-driving vehicle mobility concepts. It is claimed that not all such concepts can be easily mapped into transport modes and that it might be more appropriate to differentiate value of travel based on travel characteristics. / Denna licentiatavhandling består av en introduktion och treartiklar som på olika sätt berör värdering av restid. Vare sigvi vill det eller inte är vår vardag driven av och bunden av tid.Vi planerar vår tid, spenderar vår tid och stressar när tideninte räcker till. Det vi önskar, vill och måste göra tar tid; tidenvillkorar helt enkelt mycket i våra liv. Om det är så att vi villförflytta oss från en fysisk plats till en annan, kanske mellanhem och jobb eller skola, tar det tid. Den här specifika tiden,restiden, antas behövas på grund av behovet av att jobba, fikaeller handla, inte genom en önskan om att resa i sig (även omdet självklart finns resor vi gör för nöjes skull, där nöjet är självaresan). I och med att resan (och restiden) är nödvändig men intei sig önskvärd är det ett grundläggande antagande inom fältetför transportekonomi att människor vill minimera sin restid i såstor utsträckning som möjligt. Det är det här antagandet sommycket av planeringen och investeringarna i transporter grundarsig på. Genom att undersöka betalningsvilja hos resenärer kanman sätta ett monetärt värde på potentiellt insparad restid: tidblir pengar. Men är det verkligen så enkelt? Till att börja medär tid och pengar de facto inte samma sak. Vi kan inte sparatid på samma sätt som pengar utan sparad tid måste användasomedelbart. Det blir därmed rimligt att anta att vad man gör medden insparade tiden spelar roll eftersom tiden känns mer värd omden kan spenderas på något meningsfullt. Vad man har möjlighetatt göra beror ofta på sammanhanget och upplevs därför mindreflexibelt än när det gäller insparade pengar.Denna avhandling resonerar vidare kring frågor om förhållandetmellan tid och pengar, i synnerhet den vanligt förekommandeoch generellt accepterade monetära värderingen av restid. Tillviss del problematiserar avhandlingen antagandet att tid är pengar och frågar sig om inte för mycket fokus läggs på tidskvantitetframför tidskvalitet och att kan det vara värdefullt att reflekterakring vilka transportinvesteringar som detta gynnar. Syftet äratt undersöka om de vedertagna transportekonomiska modellersom tillämpas idag speglar sådant vi som samhälle värdesätteroch lyfta aspekter som möjligen förbises.Introduktionen till avhandlingen består av en metodologiskdiskussion kring filosofins roll i tvärvetenskapliga projekt, enöversiktlig teoretisk bakgrund till begrepp såsom rationalitetoch välfärdsekonomi och en genomgång av teman som på etteller annat sätt berör värdering av tid. Därefter sammanfattasartiklarna och introduktionen avslutas med slutsatser och ettavsnitt om möjliga framtida forskningsämnen.Den första artikeln i den här avhandlingen handlar om hurförhållandet mellan tid och pengar kan bättre förstås genom attutgå från tiden som det primära att värdesätta. Denna analysoch de insikter som analysen leder till kan därefter förklara ochbättre underbygga antaganden som görs vid modellering av beslutrörande tid. I artikeln analyseras egenskaper av tid i relation tillpengar som framkommit i beteendevetenskaplig och psykologiskforskning. I transportekonomi, likt traditionell mikroekonomi,utgår man från ett antagande om stabila rationella preferenser hosindivider. Givet skillnader mellan hur individer verkar resonerakring tid jämfört med pengar kan man dock ställa sig frågan omdet skulle kunna vara annorlunda att vara rationell med avseendepå tid jämfört med att vara rationell med avseende på pengar. Isynnerhet då det finns egenskaper hos tid som är så pass specifikaatt motsvarande egenskaper inte finns hos andra typer av objekteller varor. Sammantaget hävdar vi att det enkla förhållandetmellan tid och pengar inte är tillräckligt rättfärdigat i ljuset av defaktiska skillnaderna mellan tid och pengar som verkar föreligga.Den andra artikeln i avhandlingen rör upplevelser av restid ochförhållandet mellan upplevelsen och de teoretiska antagandenasom görs i transportekonomi. I artikeln analyserar vi upplevelser av restid hos resenärer som påverkades av det plötsliga införandetav identitetskontroller vid resor mellan Sverige och Danmark 2015.Mot bakgrund av en studie där upplevelserna dokumenteradesvisar vi på aspekter av restid som upplevs men inte speglas i vedertagnatransportekonomiska modeller. Artikeln delar upp dessaaspekter i tre kategorier: (i) aspekter rörande den faktiska restatiden och upplevelser av själva resan, (ii) kortsiktiga anpassningartill rådande omständigheter och (iii) långsiktiga anpassningar tillrådande omständigheter. Vi menar att restiden behöver sättasi ett vidare perspektiv genom att se resan och restiden i ettsammanhang där planering av vardagen är en förutsättning föratt få livet att gå ihop. Ett möjligt sådant perspektiv är att urplaneringssynpunkt sträva efter att göra tiden så ‘planerbar’ sommöjligt, alltså att underlätta individers långsiktiga och kortsiktigaplanering av både restid och resor, istället för att enkom serestid som onytta.I tredje artikeln tillämpas till viss del insikter om vad som skiljertid från pengar och dessa appliceras på värdering av restid försjälvkörande fordon. Värdet av restid beror traditionellt (blandannat) på transportmedel, det vill säga om resan görs med bil,buss eller tåg. Självkörande bilar har i litteraturen setts som ytterligareresslag, ofta en ny sorts bil. Vi menar dock att självkörandefordon kan mynna ut i många olika typer av transportmedel därvissa kommer att likna de vi har idag medan andra kommer attvara nya sett till resegenskaper. Givet att dessa egenskaper är relateradetill aspekter som påverkar resenärers värdering av restidkommer tiden alltså vara olika mycket värd. Värdering av restidför självkörande fordon bli därför mer komplext än att lägga tillett eller ens några ytterligare transportmedel. För att belysa dettagör vi i artikeln en så kallad morfologisk analys där vi spännerupp ett lösningsfält vi menar täcker in aspekter som påverkarvärderingen av restid för självkörande fordon. Sedan analyserarvi möjliga (och troliga) lösningar, där varje lösning motsvararett möjligt transportmedel, och menar att restidsvärdet för dessa lösningar rimligen bör skilja sig åt. Det leder oss till att föreslåatt ett alternativt sätt att segmentera restidsvärde skulle kunnavara att utgå från resegenskaper, snarare än transportmedel somsådana. Sådana resegenskaper skulle kunna vara privat/deladresa eller om resan sker efter tidtabell eller är “on-demand“.Sammanfattningsvis menar jag att monetär värdering av tidkan ses från tre perspektiv: (i) det linjära förhållandet mellan tidoch pengar som sådant, (ii) aggregeringen av individers insparaderestid till faktisk samhällsnytta och (iii) restidsförkortningarsplats i kostnadsnyttoanalys och transportplanering i allmänhet.Transportinvesteringar görs på lång sikt och de samhällsekonomiskakalkyler som ligger till grund för dessa investeringar behöverdärmed spegla både vårt förhållande till tid idag men även hur vikommer att förhålla oss till tiden i framtiden. Rimligen kommervi då ha lika mycket tid som idag, men kommer vårt förhållandetill tid vara detsamma?Slutligen föreslår jag i avhandlingen möjliga framtida temanatt undersöka vidare, såsom transporträttvisa, aggregering avväldigt små restidsvinster och förhållandet mellan risker ochtidsvinster. / <p>QC 20200819</p>

This work examines the effect of participants' gender and handedness on the perception of short intervals of time. The time estimation task consisted of an empty production procedure with forty trials at each of four intervals of one, three, seven, and twenty seconds. The four target intervals represent a natural logarithmic progression and a series that bracket important temporal thresholds. The order of presentation of those intervals was randomized across participants but yoked across the sexes in each of the respective dominant hand groups. The two between-subject factors, with two levels each, were sex and handedness. Participants produced forty estimates at each of the required intervals, which was the first within-subject factor, estimated interval being the other. T-tests were conducted on the dependent measures, the time estimates in terms of their variability and their central tendency with respect to the target duration. If handedness plays a significant role in timing, this may indicate differences between hemispheric functioning as a possible causal mechanism. If there is cerebral asymmetry in time perception, namely if one hemisphere is more competent regarding time perception, accuracy in judging duration should be higher for the contralateral hand. The results of the present study indicated that there are no significant differences in performance between right-handed and left-handed participants, or between male and female participants, in the estimation of short intervals of time.

The aim of this interdisciplinary study is to reconstruct the evolution of our changing conceptions of time in the light of scientific discoveries. It will adopt a new perspective and organize the material around three central themes, which run through our history of time reckoning: cosmology and regularity; stasis and flux; symmetry and asymmetry. It is the physical criteria that humans choose ¿ relativistic effects and time-symmetric equations or dynamic-kinematic effects and asymmetric conditions ¿ that establish our views on the nature of time. This book will defend a dynamic rather than a static view of time.

Time Sensitive Networking (TSN) is a standard that extends Ethernet, providing deterministic guarantees to internal communications. The standard is finding use in many different fields such as modern cars whose networks are getting increasingly complex. One problem with TSN is the NP-hard problem of scheduling network flows, the process in which schedules are made to ensure that network flows demanding real-time guarantees have their requirements met.The goal of thesis is to implement two different scheduling algorithms. The evaluation of the implementations measure how they perform in regards to finding possible schedules and for how much time they take with an increasing number of network flows to schedule. The algorithms approaches to scheduling are then discussed and judged in comparison with the results. This thesis implements two different algorithms, a fine-grained algorithm and a coarse-grained algorithm. The difference between the algorithms lie in how fine-grained their scheduling is. Where the fine-grained algorithm adopts the lowest resolution permissible, the coarse-grained algorithm achieves the highest resolution possible in the schedule. The results show that the coarse-grained algorithm becomes unacceptably slow because of its fine-grained scheduling. In a scenario where algorithms 1 and 2 work with the same flows, the coarse-grained algorithm is 42x slower than the fine-grained algorithm in the worst case.The conclusion is that the finest possible scheduling is not a feasible approach because of it taking too much time to execute for a very small amount of flows. / Time Sensitive Networking (TSN) är en standard som utökar Ethernet genom att lägga till deterministiska garantier till intern kommunikation. Standarden har börjat användas inom fält såsom moderna bilar vars nätverk blir allt mer komplexa. Ett problem med TSN är det NP-hard svåra problemet med att schemalägga nätverksflöden, processen i vilket scheman uträknas för att garantera att nätverksflöden som kräver realtidsgarantier får sina krav uppfyllda. Uppsatsens mål är att implementera två olika schemaläggningsalgoritmer. Evalueringstesterna mäter algoritmernas förmåga att finna möjliga scheman för olika mängder av nätverksflöden och hur lång tid det tar.Algoritmernas tillvägagångssätt för schemaläggning jämförs och bedöms därefter.Denna uppsats implementerar två olika algorithmer, en finkorning algorithm och en grovkornig algoritm. Namnen kommer från finkornigheten i algoritmernas schemaläggning. Den finkorniga algoritmen schemalägger med finkornighet och den grovkorniga algoritmen schemalägger med grovkornighet. Resultatet från testerna och evalueringen visar att när algoritmerna schemalägger samma flöden tar den grovkorniga algoritmen som värst 42 gånger mer tid att slutföra sina beräkningar. Slutsatsen är att finkorning schemaläggning är inte applicerbar då det tar för lång tid att utföra för en väldigt liten mängd flöden.

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This dissertation presents a class of utility accrual scheduling and synchronization algorithms for dynamic, single and multiprocessor real-time systems. Dynamic real-time systems operate in environments with run-time uncertainties including those on activity execution times and arrival behaviors. We consider the time/utility function (or TUF) timing model for specifying application time constraints, and the utility accrual (or UA) timeliness optimality criteria of satisfying lower bounds on accrued activity utility, and maximizing the total accrued utility. Efficient TUF/UA scheduling algorithms exist for single processors---e.g., the Resource-constrained Utility Accrual scheduling algorithm (RUA), and the Dependent Activity Scheduling Algorithm (DASA). However, they all use lock-based synchronization. To overcome shortcomings of lock-based (e.g., serialized object access, increased run-time overhead, deadlocks), we consider non-blocking synchronization including wait-free and lock-free synchronization. We present a buffer-optimal, scheduler-independent wait-free synchronization protocol (the first such), and develop wait-free versions of RUA and DASA. We also develop their lock-free versions, and upper bound their retries under the unimodal arbitrary arrival model. The tradeoff between wait-free, lock-free, and lock-based is fundamentally about their space and time costs. Wait-free sacrifices space efficiency in return for no additional time cost, as opposed to the blocking time of lock-based and the retry time of lock-free. We show that wait-free RUA/DASA outperform lock-based RUA/DASA when the object access times of both approaches are the same, e.g., when the shared data size is so large that the data copying process dominates the object access time of two approaches. We derive lower bounds on the maximum accrued utility that is possible with wait-free over lock-based. Further, we show that when maximum sojourn times under lock-free RUA/DASA is shorter than under lock-based, it is a necessary condition that the object access time of lock-free is shorter than that of lock-based. We also establish the maximum increase in activity utility that is possible under lock-free and lock-based. Multiprocessor TUF/UA scheduling has not been studied in the past. For step TUFs, periodic arrivals, and under-loads, we first present a non-quantum-based, optimal scheduling algorithm called Largest Local Remaining Execution time-tasks First (or LLREF) that yields the optimum total utility. We then develop another algorithm for non-step TUFs, arbitrary arrivals, and overloads, called the global Multiprocessor Utility Accrual scheduling algorithm (or gMUA). We show that gMUA lower bounds each activity's accrued utility, as well as the system-wide, total accrued utility. We consider lock-based, lock-free, and wait-free synchronization under LLREF and gMUA. We derive LLREF's and gMUA's minimum-required space cost for wait-free synchronization using our space-optimal wait-free algorithm, which also applies for multiprocessors. We also develop lock-free versions of LLREF and gMUA with bounded retries. While the tradeoff between wait-free LLREF/gMUA versus lock-based LLREF/gMUA is similar to that for the single processor case, that between lock-free LLREF/gMUA and lock-based LLREF/gMUA hinges on the cost of the lock-free retry, blocking time under lock-based, and the operating system overhead. / Ph. D.

Traffic congestion has continued to grow as a result of urbanization, which is associated with an increase in car ownership. As a way to improve the efficiency of the transportation system, emerging technologies including Connected Automated Vehicles (CAVs), loop detectors, Advanced Traveler Information Systems (ATISs), and Advanced Public Transportation Systems (APTSs) are being deployed. One of the successful techniques that has demonstrated benefits for system users, operators and agencies is Transit Signal Priority (TSP). TSP favors transit vehicles in the allocation of green times at traffic signals. A successful deployment of TSP depends on different factors including the prediction of various components of transit vehicle travel times to predict when a vehicle would arrive at a traffic signal. Current TSP state-of-the-art and state-of-practice disregards the impact of bus stops, transit vehicle characteristics, driver, and the prevailing traffic conditions on the predicted arrival time of transit vehicles at traffic signals. Considering these factors is important the success of TSP hinges on the ability to predict transit vehicle arrival times at traffic signals in order to provide these vehicles with priority service. The main contribution of this research effort relates to the modeling of the various components of transit vehicle travel times. This model explicitly captures the impact of passengers, drivers and vehicle characteristics on transit vehicle travel times thus providing better models for use in various transit applications, including TSP. Furthermore, the thesis presents a comprehensive understanding of the determinants of each travel time component. In essence, the determinants of each component, the stochasticity in these determinants and the correlation between them are explicitly modeled and captured. To achieve its contribution, the study starts by improving the current state-of-the-art and state-of-practice transit vehicle boarding/alighting (BA) models by explicitly accounting for the different factors that impact BA times while ensuring a relatively generalized formulation. Current formulations are specific for the localities and bus configurations that they were developed for. Alternatively, the proposed BA time model is independent of the transit vehicle capacity and transit vehicle configuration (except for the fact that it is only valid for two-door buses – a separate door for alighting and boarding the bus) and accounts for the number of on-board passengers, boarding and alighting passengers. The model also captures the stochasticity and the correlation between the model coefficients with minimum computational requirements. Next the model was extended to capture the bus driver and vehicle impacts on the transit vehicle delay in the vicinity of bus stops, using a vehicle kinematics model with maximum speed and acceleration constraints to model the acceleration/deceleration delay. The validation of the model was done using field data that cover different driving conditions. Results of this work found that the proposed formulation successfully integrated the human and vehicle characteristics component in the model and that the new formulation improves the estimation of the total delay that transit vehicles experience near bus stops. Finally, the model was extended to estimate the time required to merge into the adjacent lane and the time required to traverse a queue upstream of a traffic signal. The final part of this study models the bus arrival time at traffic signal using shockwave and prediction model in a connected environment. This section aims to model the transit vehicle arrival time at traffic signal considering the impact of signal timing and the prevailing traffic conditions. In summary, the proposed model overcomes the current state-of-the-art models in the following ways: 1) it accounts for the vehicle capacity and the number of on-board passengers on bus BA times, 2) it captures the stochasticity in the bus stop demand and the associated BA times, 3) it captures the impact of the traffic in modeling the delay at a bus stop , 4) it incorporates the driver and vehicle impact by modeling the acceleration and deceleration time, and 5) it uses shockwave analysis to estimate bus arrival times through the use of emerging technology data. Through statistical modeling and evaluation using field and simulated data, the model overcomes the current state-of practice and state-of art transit vehicle arrival time models. / Doctor of Philosophy / Traffic congestion grows rapidly causing increment in travel time, reducing travel time reliability, and reducing the number of public transportation riders. Using the Advanced Public Transportation Systems (APTS) technology with Advanced Traveler Information Systems (ATISs) helps in improving transportation network travel time by providing real-time travel information. One of the successful techniques that has demonstrated benefits for system users, operators and agencies is Transit Signal Priority (TSP). A successful deployment of TSP depends on different factors including the prediction of various components of transit vehicle travel times to predict when a vehicle would arrive at a traffic signal. Current TSP state-of-the-art and state-of-practice disregards the impact of bus stops, transit vehicle characteristics, driver, and the prevailing traffic conditions on the predicted arrival time of transit vehicles at traffic signals. The difficulty of modeling the various determinants of the transit vehicle travel time as explicit variables rather than include some of them are implicitly modeled due to two main reasons. First, there are various significant factors affecting estimating the transit vehicle arrival time including; the passenger demand at bus stop, driver characteristics, vehicle characteristics and the adjacent prevailing traffic conditions. Second, the stochasticity and the fluctuation nature of each variables as they differ spatiotemporally. The research presented in this thesis provides a comprehensive investigation of the determinants of different transit vehicle travel time components of the transit vehicle arrival time at traffic signal leading to a better implementing of TSP. This study was initiated due to the noticeable overlooking of the different factors including human and vehicle behavior in the current state-of-practice and state-of-art which, as a result, fails to capture and incorporate the impact of these components on the implementing of TSP.

We consider the problem of scheduling real-time tasks on a multiprocessor system. Our primary focus is scheduling on multiprocessor systems where the total task utilization demand, U, is greater than m, the number of processors on a multiprocessor system---i.e., the total available processing capacity of the system. When U > m, the system is said to be overloaded; otherwise, the system is said to be underloaded. While significant literature exists on multiprocessor real-time scheduling during underloads, little is known about scheduling during overloads, in particular, in the presence of task dependencies---e.g., due to synchronization constraints. We consider real-time tasks that are subject to time/utility function (or TUF) time constraints, which allow task urgency to be expressed independently of task importance---e.g., the most urgent task being the least important. The urgency/importance decoupling allowed by TUFs is especially important during overloads, when not all tasks can be optimally completed. We consider the timeliness optimization objective of maximizing the total accrued utility and the number of deadlines satisfied during overloads, while ensuring task mutual exclusion constraints and freedom from deadlocks. This problem is NP-hard. We develop a class of polynomial-time heuristic algorithms, called the Global Utility Accrual (or GUA) class of algorithms. The algorithms construct a directed acyclic graph representation of the task dependency relationship, and build a global multiprocessor schedule of the zero in-degree tasks to heuristically maximize the total accrued utility and ensure mutual exclusion. Potential deadlocks are detected through a cycle-detection algorithm, and resolved by aborting a task in the deadlock cycle. The GUA class of algorithms include two algorithms, namely, the Non-Greedy Global Utility Accrual (or NG-GUA) and Greedy Global Utility Accrual (or G-GUA) algorithms. NG-GUA and G-GUA differ in the way schedules are constructed towards meeting all task deadlines, when possible to do so. We establish several properties of the algorithms including conditions under which all task deadlines are met, satisfaction of mutual exclusion constraints, and deadlock-freedom. We create a Linux-based real-time kernel called ChronOS for multiprocessors. ChronOS is extended from the PREEMPT_RT real-time Linux patch, which provides optimized interrupt service latencies and real-time locking primitives. ChronOS provides a scheduling framework for the implementation of a broad range of real-time scheduling algorithms, including utility accrual, non-utility accrual, global, and partitioned scheduling algorithms. We implement the GUA class of algorithms and their competitors in ChronOS and conduct experimental studies. The competitors include G-EDF, G-NP-EDF, G-FIFO, gMUA, P-EDF and P-DASA. Our study reveals that the GUA class of algorithms accrue higher utility and satisfy greater number of deadlines than the deadline-based scheduling algorithms by as much as 750% and 600%, respectively. In addition, we observe that G-GUA accrues higher utility than NG-GUA during overloads by as much as 25% while NG-GUA satisfies greater number of deadlines than G-GUA by as much as 5% during underloads. / Master of Science

Because the operational characteristics of signalized intersections near highway-railroad grade crossings (IHRGCs) are different from those of signalized intersections located elsewhere in the traffic system, standard operational strategies do not apply. This is because safe operation at IHRGCs takes precedence over all other objectives. Because the prime objective of the current preemption methods is to clear the crossing, secondary objectives such as safe pedestrian crossing time and minimized delay are given less consideration or ignored completely. Consequently, state-of-the-practice strategies may cause serious pedestrian safety and efficiency problems at IHRGCs. Therefore, there is a definite need for research on how to improve traffic signal preemption strategies. An important element of preemption strategy is detection of trains and prediction of arrival times. However, because of the limitations of current detection technologies, estimation algorithms, etc., there is a wide range in these warning times. In this dissertation, a new train-arrival prediction algorithm was developed using detection equipment located farther upstream from the HRGC. The state-of-the-art transition preemption strategy (TPS) was developed to ensure that as preemption is initiated by approaching trains, the signal display does not change in a manner that endangers either pedestrians or drivers. However, because it does not account for the variability of predicted train arrival times, there is still a possibility of failure. Therefore, a new transition preemption algorithm that is specifically designed to improve intersection performance while maintaining or improving the current level of safety is developed. This dissertation developed a preemption strategy (TPS3) that uses better train arrival time estimates to improve the safety and efficiency of IHRGCs. The approach was simulated on a test bed in College Station, Texas, and it was concluded that the new TPS improves the safety and operation of intersections near highway-railroad grade crossings.