Exit Lane Research Articles

Comparison of Reticular and Rectal Core Body Temperatures in Lactating Dairy Cows

The Phase IV Cattle Temperature Monitoring System (CTMS; Phase IV Engineering Inc., Boulder, CO) marketed by MaGiiX (MaGiiX Inc., Post Falls, ID) uses a passive bolus equipped with a temperature sensor, a panel reader placed at a parlor entrance or exit to query the bolus, and a software package to collect, analyze, and view data. The biologically inert bolus resides in the cow's reticulum and is queried each time the cow passes the reader. Reticular temperature (RETT) and rectal temperature (RECT) were recorded simultaneously in the milking parlor exit lane in 4 consecutive milkings in each of 4 seasons, totaling 16 measurements per cow. The RETT were obtained by using the phase IV CTMS, whereas the RECT were obtained manually with a GLA M750 thermometer (GLA Agricultural Electronics, San Luis Obispo, CA). Data were edited to remove RETT likely to have been affected by a recent drinking bout. For the 2,042 observations used in analyses, means (±SD) were 39.28 (±0.41), 38.83 (±0.36), and 0.45 (±0.33) for RETT, RECT, and the difference between RETT and RECT, respectively. The RETT and RECT were strongly correlated (r = 0.645). The relationship between RETT and RECT varied by season, milking, housing system, and parity. Because dairy producers and veterinarians are accustomed to viewing rectal temperatures, equations to adjust reticular temperatures to a rectal-based scale may increase the utility of the phase IV CTMS. The resulting conversion equations were RECT = 19.23 + 0.496(RETT) for the a.m. milking and RECT = 15.88 + 0.587(RETT) for the p.m. milking.

Observational Analysis of Pedestrian, Bicyclist, and Motorist Behaviors at Roundabouts in the United States

Roundabouts continue to gain popularity in the United States as an intersection treatment for improving operational efficiency and motor vehicle safety. A number of studies conducted in the United States and other countries have shown the benefits of roundabouts for these purposes. However, there is still concern that roundabouts may not provide safety or operational benefits for pedestrians and bicyclists. Crash-based studies of pedestrian and bicyclist safety in the United States have fallen short because of the relatively small number of roundabouts installed to date, which results in sample size issues due to the low number of motor vehicle collisions involving pedestrians and bicyclists. This study was undertaken as part of an NCHRP project. This paper focused on analyzing the interactions between motorists and pedestrians or bicyclists at roundabouts. This research did not find any substantial safety problems for nonmotorists at roundabouts based on conflicts or collisions. At the same time, the findings from behavioral observation have highlighted some aspects of roundabout design that require additional care to ensure safe access for pedestrians and bicyclists. Emphasis needs to be placed on designing exit legs to ensure proper sight lines and motor vehicle speeds. The junction of the circulatory lane and exit lane was observed to be the location of greatest risk for bicyclists. Multilane roundabouts may require additional traffic control measures to ensure safe access for pedestrians.

Including Exiting Vehicles in Capacity Estimation at Single-Lane U.S. Roundabouts

The current model used in the United States to predict approach capacity at a single-lane roundabout uses information about entry driver behavior in response to the circulating traffic stream only. There is no procedure for including exiting vehicles in capacity estimation. Exiting vehicles are vehicles that leave the circulating stream of traffic by maneuvering into the exit lane at a roundabout approach. Exiting vehicles are known to have an effect on capacity at roundabout approaches in other countries, but their effect in the United States is not known. The purpose of this research is to determine whether including exiting vehicles improves capacity estimation at a roundabout approach. An exploration of the relationships of the proportion of exiting vehicles and the width of the splitter island to approach capacities is included. Capacities were estimated both with and without exiting vehicles as part of the conflicting flow and compared with measured field capacities. The findings demonstrate that capacity estimates with exiting vehicles result in improved prediction of the actual capacity of a roundabout approach over estimates without exiting vehicles. The proportion of exiting vehicles in the major stream and the width of the splitter island appear to provide some benefit in capacity prediction, but exactly how these parameters can be incorporated into the capacity prediction process must be further explored.

Observational Analysis of Pedestrian, Bicyclist, and Motorist Behaviors at Roundabouts in the United States

Roundabouts continue to gain popularity in the United States as an intersection treatment for improving operational efficiency and motor vehicle safety. A number of studies conducted in the United States and other countries have shown the benefits of roundabouts for these purposes. However, there is still concern that roundabouts may not provide safety or operational benefits for pedestrians and bicyclists. Crash-based studies of pedestrian and bicyclist safety in the United States have fallen short because of the relatively small number of roundabouts installed to date, which results in sample size issues due to the low number of motor vehicle collisions involving pedestrians and bicyclists. This study was undertaken as part of an NCHRP project. This paper focused on analyzing the interactions between motorists and pedestrians or bicyclists at roundabouts. This research did not find any substantial safety problems for nonmotorists at roundabouts based on conflicts or collisions. At the same time, the findings from behavioral observation have highlighted some aspects of roundabout design that require additional care to ensure safe access for pedestrians and bicyclists. Emphasis needs to be placed on designing exit legs to ensure proper sight lines and motor vehicle speeds. The junction of the circulatory lane and exit lane was observed to be the location of greatest risk for bicyclists. Multilane roundabouts may require additional traffic control measures to ensure safe access for pedestrians.

Including Exiting Vehicles in Capacity Estimation at Single-Lane U.S. Roundabouts

The current model used in the United States to predict approach capacity at a single-lane roundabout uses information about entry driver behavior in response to the circulating traffic stream only. There is no procedure for including exiting vehicles in capacity estimation. Exiting vehicles are vehicles that leave the circulating stream of traffic by maneuvering into the exit lane at a roundabout approach. Exiting vehicles are known to have an effect on capacity at roundabout approaches in other countries, but their effect in the United States is not known. The purpose of this research is to determine whether including exiting vehicles improves capacity estimation at a roundabout approach. An exploration of the relationships of the proportion of exiting vehicles and the width of the splitter island to approach capacities is included. Capacities were estimated both with and without exiting vehicles as part of the conflicting flow and compared with measured field capacities. The findings demonstrate that capacity estimates with exiting vehicles result in improved prediction of the actual capacity of a roundabout approach over estimates without exiting vehicles. The proportion of exiting vehicles in the major stream and the width of the splitter island appear to provide some benefit in capacity prediction, but exactly how these parameters can be incorporated into the capacity prediction process must be further explored.

Traffic behavior near an off ramp in the cellular automaton traffic model.

In this paper, we investigate the off-ramp system on the highway using the cellular automaton traffic model. Both the system without an exit lane (case 1) and that with an exit lane (case 2) are considered. The phase diagram and its variation with L(D) (the length of exit lane in case 2 and the length of a special lane-changing section in case 1) is studied. Two phase regions are found in case 1 and a new phase, i.e., the maximum flux phase, is reported in case 2. The density (velocity) distribution near the off ramp and the influence of L(D) on the traffic flow are also discussed in both cases.

Signing Two-Lane Freeway Exits with an Option Through Lane in Extreme Conditions: Anatomy of Drivers’ Behavior

Two-lane freeway exits in which the left-hand exit lane also continues as a through (option) lane are becoming increasingly common. Potential problems can arise at these exits when drivers become confused by the signing and can lead to increases in driver frustration, incidents, and congestion. These problems have not been studied in any detail, especially in circumstances in which the signs recommended in the Manual on Uniform Traffic Control Devices for Streets and Highways cannot be used. Such is the case in the underground sections of I-93 through downtown Boston, Massachusetts, where the signs can be no more than 3 ft high. To arrive at a better understanding of these problems, the Massachusetts Highway Department evaluated a number of different ways of informing drivers that the left-hand lane of a two-lane exit functioned as both an exit lane and a through lane. The entire underground sections of northbound and southbound I-93 were simulated on a computer. Participants in an experiment sat in an actual car surrounded by three screens onto which was projected the virtual world and manipulated the controls of the car just as they would those of an ordinary vehicle. The participants were given a particular destination on each drive. The exact path was recorded, and misses and unnecessary lane changes could be derived from the recording. Six different signs were evaluated in three experiments. A function that could be used to rank the effectiveness of a given sign on the basis of the participants’ different responses to the sign was developed. Clear recommendations for the signing of two-lane freeway exits with an option through lane in extreme conditions emerged from the experiments.

Study of freeway traffic near an off-ramp

A bottleneck with a diminished capacity is shown to have arisen on a freeway segment whenever queues from the segment's off-ramp spilled-over and occupied its mandatory exit lane. Although the ramp's queues were confined to the right-most exit lane, non-exiting drivers reduced their speeds upon seeing these queues and this diminished flows in all lanes. It is also shown that the lengths of these exit queues were negatively correlated with the discharge flows in the freeway segment's adjacent lanes; i.e., longer exit queues from the over-saturated off-ramp were accompanied by lower discharge rates for the non-exiting vehicles. Whenever the off-ramp queues were prevented from spilling-over to the exit lane (by changing the logic of a nearby traffic signal), much higher flows were sustained on the freeway segment and a bottleneck did not arise there. These observations underscore the value of control strategies that enable diverging vehicles to exit a freeway unimpeded.

Drivers’ Understanding of Overhead Freeway Exit Guide Signs: Evaluation of Alternatives with an Advanced Fixed-Base Driving Simulator

In the near future, Route 1A southbound as it passes around Logan International Airport in Boston, Massachusetts, will be rebuilt. The existing four-lane highway will split into three different roadways: two one-lane exits and one two-lane throughway. Drivers will have very little time to decide which lane or lanes to take for a given destination. Given the complex geometry and small warning time, there is some concern that drivers will either miss the Logan exit altogether (leading to a long and frustrating detour around Logan) or make a decision at the last moment to move into the exit lane (leading to a potential safety problem). Proposed and alternative ways of signing exits such as this one with complex multiple splits were evaluated on an advanced fixed-base driving simulator. The virtual roadways and signs were built using the actual engineering design drawings. Drivers sit in a real Saturn and operate the controls of this vehicle just as they would those of a normal vehicle. They are given Logan as their target destination. The alternative freeway guide signs were found to improve indices of driver safety and satisfaction. Specifically, drivers using the alternative signs move into the exiting lane sooner, make fewer double lane changes, and miss their exit less often. The results have implications more generally for the design and testing of highway guide signs using a driving simulator.

Keeping cows cool (2000)

Heat stress occurs when a dairy cow's internal heat load is greater than her capacity to lose unwanted heat to the environment. Effects of heat stress include: increased respiration rate, increased water intake, increased sweating, decreased dry matter intake, slower rate of feed passage, decreased blood flow to internal organs, decreased milk production, and poor reproductive performance. Lower milk production and reproductive performance cause economic losses to dairy producers. The ordered priorities for reducing heat are: increasing water availability; providing shade in the housing areas (both dry and lactating cows) and holding pen; reducing walking distance to the parlor; reducing time in the holding pen; improving holding pen ventilation and freestall ventilation; adding cooling for the holding pen and exit lane; cooling close-up cows (3 wk before calving); cooling housing for fresh and earlylactation cows; and cooling housing for midand late-lactation cows.; Dairy Day, 2000, Kansas State University, Manhattan, KS, 2000;