Weather and road capacity

The paper presents estimations of the effect of bad weather on the observed speed on a Danish highway section; Køge Bugt Motorvejen. The paper concludes that weather, primarily precipitation and snow, has a clear negative effect on speed when the road is not in hypercongestion mode. Furthermore, the capacity of the highway seems to be reduced in bad weather and there are indications that travel time variability is also increased, at least in free-flow conditions. Heavy precipitation reduces speed and capacity by around 5-8%, whereas snow primarily reduces capacity. Other weather variables such as darkness, frost, wind and fog also have effects, but they are minor and are hard to assess exactly. In general, the effects are less than found in other studies, primarily from North America. The effects are estimated using a two-step procedure. In step 1 the log to travel time is regressed non-parametrically against traffic density and in step 2 the residuals from step 1 are regressed linearly against the weather variables. The choice of a non- parametric method is made to avoid constricting ties from a parametric specification and because the focus here is not on the relationship between traffic flow and speed

Comparison of Student Versus Employee Test Populations for Warning Sign Research Based on Severity Ratings for Signal Words

Most studies of warning signs involve undergraduate students as subjects. This paper reports a direct comparison of findings from an undergraduate population and an employed population. The 48 employed subjects from this study were compared with 59 undergraduate subjects from a companion study. Subjects from both populations were shown the same signs and asked to rate the severity level connoted by each sign. The signs differed only in signal word. Results for each population indicated that signal word had a highly significant effect on severity ratings. When the two populations were compared for ratings of each signal word, the only significant difference was for Caution. Median ratings of each population were the same: Deadly (4), Danger (3), Warning (2), Caution (1), and Notice (0)

Including changes in security of supply in cost benefit analysis – an application to oil prices in the transport sector

This paper contains a tentative suggestion of how to take into account changes in security of supply in real world cost-benefit analysis. Assuming that consumers are risk avers, security of supply can be viewed as a matter of avoiding oscillations in consumption originating from volatile prices of for in- stance oil. When the government makes transport related choices on behalf of the consumers, the effect on oscillations in general consumption should be included in the policy assessment taking into account the most significant correlations between prices on alternative fuels and between fuel prices and consumption in general. In the paper, a method of valuing changes in security of supply based on portfolio theory is applied to some very simple transport related examples. They indicate that includ- ing the value of changes in security of supply often makes very little difference to the results of cost benefit analysis, but more work has to be done on quantifying, among other things, consumers’ risk aversion and the background standard deviation in total consumption before firm conclusions can be drawn

Array E S-Band compatibility test results analysis

This report documents an investigation of the MSFN/ALSEP S-Band Compatibility Test Results and provides a rationale and recommendation relative to the test validity and relative to Command Decoder Circuit Modifications made subsequent to the test performance.prepared by C. Jensen, D. Thomas

Analyse af rejsetidsvariabilitet på danske motorveje

Variabilitet i rejsetider, som betyder at det er vanskeligt at forudsige hvor lang tid en tur tager, er en negativ konsekvens af bl.a. trængsel og hændelser på vejene. I samfundsøkonomiske analyser håndteres det i dag ved, at tidsværdien af forsinkelser er højere end tidsværdien for almindelige rejsetid. Denne metode er dog ikke altid tilfredsstillende, og grundlaget er forholdsvis svagt dokumenteret. Transport DTU og Vejdirektoratet har forsøgt at anvende GPS-data til at kortlægge sammenhængen mellem forsinkelse og variabilitet, for at undersøge om det er muligt at forudsige rejsetidsvariabilitet ud fra forsinkelser. Hvis det er muligt, vil man kunne forudsige ændringer i rejsetidsvariabilitet ud fra output fra trafikmodeller, og variabilitet vil dermed kunne værdisættes mere direkte i den samfundsøkonomiske analyse. Resultaterne af denne analyse viser en tydelig sammenhæng mellem forsinkelse og variabilitet, hvilket betyder, at det måske er muligt at opstille en simpel efterberegningsmodel til LTM, der beregner ændringer i rejsetidsvariabilitet som følge af transport- og infrastrukturprojekter. I forbindelse med analysen er det dog tydeligt, at der er behov for videreudvikling af metoden, før den implementeres i den samfundsøkonomiske analyse

Empirisk undersøgelse af økonomiske forhold med betydning for godstrans- portens omfang og fordeling på transportformer.

Formålet med projektet er bl.a. at besvare spørgsmålet om man kan ændre transportens omfang og sammensætning vha. økonomiske midler som fx afgifter. Hvordan reagerer transportefterspørgerne på ændringer i prisen på transport? Kan man ad afgiftsvejen ændre transportens omfang eller sammensætning på transportmåder og dermed nå et lavere energiforbrug? Metoden til besvarelse af disse spørgsmål er økonometrisk: Vha. estimationer med tidsserier på makroniveau forsøges det at vurdere transportefterspørgernes (in casu industrien i Danmark) følsomhed overfor priserne på transport. Generelt peger estimationerne på, at der ser ud til at være en følsomhed i transportefterspørgslen overfor priserne på transport generelt, og at der er en hvis substitution mellem tog og bil, men kun i ringe grad mellem skib og de øvrige transportmåder. Resultaterne må betragtes som meget foreløbige og usikre. Eksempel på anvendelse af resultaterne for den langsigtede effekt på fremstillingserhvervet af en afgift, der fordyrer biltransporten med 10%. Der fås et fald i den samlede transportefterspørgsel på ca. 6% og dertil en omfordeling bort fra biltransport, således at den samlede effekt bliver en stigning for tog på ca. 5% og et fald for bil på ca. 9%, mens ændringen for skib er tæt på 0%