Roadside Control Research Articles

Rapid Testing of Δ9-Tetrahydrocannabinol and Its Metabolite On-Site Using a Label-Free Ratiometric Fluorescence Assay on a Smartphone.

Excessive consumption of Δ9-tetrahydrocannabinol (THC) severely endangers human health and has raised public safety concerns. However, its quantification by readily rapid tools with simplicity and low cost is still challenging. Herein, we found that a G-rich THC aptamer (THC1.2) can tightly bind to thioflavin T (ThT) with strong fluorescence, which would be specifically quenched in the presence of THC. Based on that, a label-free ratiometric fluorescent sensor for the sensing of THC and its metabolite (THC-COOH) based on THC1.2/ThT as a color emitter and red CdTe quantum dots as reference fluorescence was constructed. Notably, a transition of the fluorescent color of the ratiometric probe from green to red can be instantly observed upon the increased concentration of THC and THC-COOH. Furthermore, a portable smartphone-based fluorescence device integrated with a self-programmed Python program was fabricated and used to accomplish on-site monitoring of THC and THC-COOH within 5 min. Under optimized conditions, this ratiometric fluorescent sensor allowed for an instant response toward THC and its metabolite with considerable limits of detection of 97 and 254 nM, respectively. The established sensor has been successfully applied to urine and saliva samples and exhibited satisfactory recoveries (88-116%). This ratiometric fluorescent sensor can be used for the simultaneous detection of THC and THC-COOH with the advantages of rapidness, low cost, ease of operation, and portability, providing a promising strategy for on-site detection and facilitating law enforcement regulation and roadside control of THC.

Adaptive Highway Networks: An IoT Solution for Improving Road Safety at Turnovers and U-Turns

Highway construction is a crucial component of any region's infrastructure, and it is carried out in several different ways nowadays. Adaptive Highways Network (AHN) uses sensors and microprocessors for automatic design. Innovative highway design employs roadside controls and intelligent vehicles for traffic management and control. The Automated Highway System enhances highway safety, operational efficiency, and other vehicle and user characteristics. This innovation has enhanced the architecture of highways and reduced vehicle emissions. AHS, or Smart Road, is a projected intelligent transportation system technology for driverless automobiles on specific roadways. It is commonly employed to alleviate traffic congestion since it reduces following distances and permits more vehicles on the road. Together, the car and the roadway strive to avoid barriers, boost traffic flow, and decrease congestion. The AHS concept integrates vehicle intelligence, intelligent highway infrastructure, and vehicle-to-infrastructure communication technology.

Randomly controlled drivers using minimally invasive sampling: assessment of drug prevalence in Western Switzerland over two time periods

BackgroundAccording to the World Health Organization, road traffic injuries lead to 1.3 million deaths each year and represent the leading cause of death for young adults under 30 years old. The use of psychoactive substances, including alcohol, drugs and pharmaceuticals, is a well-known risk factor for road traffic injuries. Our study aims to assess the prevalence of substances consumed by drivers in western Switzerland. Such studies are pivotal to improving prevention and developing public awareness campaigns.MethodsTo assess the prevalence of psychoactive substances among drivers, roadside controls were performed in collaboration with local police, using their classical sampling procedures to detect drivers under the influence of drugs or alcohol over two time periods (P1: 2006-2008, P2: 2017-2020). When impaired driving was not suspected by the police, minimally invasive sampling strategies (i.e., oral fluids during P1 and dried blood spots during P2) were performed on volunteer drivers after a road safety survey. A posteriori analyses and statistical interpretation were then performed.ResultsAmong the 1605 drivers included in the study, 1048 volunteers provided an oral fluid sample, while 299 provided a dried blood spot sample. The percentage of drivers testing positive for at least one substance that can impact driving abilities was stable over time, with a rate of 10.5% positivity measured over both periods. Considering the different categories of substances, a slight variation was observed between both periods, with 7.6 and 6.3% of pharmaceuticals and 3.6 and 4.9% of illicit drugs for P1 and P2, respectively. Regarding the consumption of illicit drugs, the highest percentage of positivity was measured in biological fluids of drivers under the age of 35, during nights and week-ends, periods which are considered particularly prone to fatal accidents for this age group. Disturbingly, the road safety survey highlighted that drivers’ perception of the risk of getting positively controlled while driving after drug consumption is low (3.3 on a 1-to-10 scale, N = 299).ConclusionThe number of positive cases measured in voluntary drivers who passed the preliminary police check demonstrates the importance of systematic biofluid sampling strategies regarding driving under the influence of psychoactive substances. Although the number of fatal road accidents globally has decreased over time, the results of this study reveal the need for both better prevention and deterrent processes that could potentially reduce the risk of fatal road accidents associated with drug consumption.

The Evaluation of Blood Alcohol Concentration of Drivers Involved in Traffic Accidents or Suspected for Alcohol in The Roadside Controls in Four Big Cities of Turkey

The Evaluation of Blood Alcohol Concentration of Drivers Involved in Traffic Accidents or Suspected for Alcohol in The Roadside Controls in Four Big Cities of Turkey

A novel solution for smart unmanned minibus based on intelligent fusion sensing technology

Thanks to recent developments in artificial intelligence and smart control technologies, unmanned vehicles are becoming pervasively adopted in a variety of scenarios. As a representative example, unmanned minibuses are integrations of vehicle level intelligence and internet of vehicles, where intelligent link mainly depends on the recognition of environment and precise control of drive-by-wire chastises. On top of these, decision-making systems for driving control can be fulfilled to achieve continuous improvement in safety and reliability. The most important parts of the telematics system include high precision map and positioning, which are the foundation for cooperation among vehicles, road-side control units, and cloud-side centers. In this work, we present a solution for unmanned minibuses that integrated smart features for unmanned driving scenarios. Both hardware design and software capabilities are presented. Prototypes have been manufactured and gone through multiple tests, which indicates feasibility of the proposed solution.

Driving under the influence of cocaine: Quantitative determination of basic drugs in oral fluid obtained during roadside controls and a controlled study with cocaine users.

Using the Belgian Drugs and Driving procedure, 36% of the cocaine-positive oral fluid (OF) screening results were not confirmed in plasma. This study investigates the impact of the choice of screening devices and confirmation matrix on the detection of cocaine use. An ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method quantifying cocaine, benzoylecgonine (BZE), and other basic drugs in OF was developed and validated. This method monitored OF samples obtained either from a roadside (n=12) or a double-blind controlled study with cocaine users (n=10) who were given either a capsule containing 300mg of cocaine-HCl or a placebo. The OF data were compared to plasma concentrations to obtain concentration-time profiles. In addition, the sensitivity and accuracy of the Drugwipe5S® was assessed. A significant difference between the OF volume collected at baseline/placebo (median 0.93mL [range 0.43-1.92mL]) or after cocaine-HCL intake (0.79mL [0.30-1.21mL]) was observed. The median OF/Plasma at the 3 collection time points were 10.7, 13.8, 6.7 for cocaine and 0.8, 1.7, 0.8 for BZE, respectively. The Drugwipe5S® detected cocaine use until at least 4hours after intake. When applying the Belgian legal confirmation decision limit of 10ng/mL in OF, an accuracy of 75%-98% was observed, depending on the study setting. Cocaine concentrations in OF were much higher and were detected longer as compared to plasma, when applying the same decision limit. From a toxicological viewpoint, the longer detection window with the higher sensitivity of Cocaine and BZE is beneficial to detect drivers in the crash/fatigue phase.

MODELLING OF DYNAMIC SPEED LIMITS USING THE MODEL PREDICTIVE CONTROL

The article considers the issues of traffic management using intelligent system “Car-Road” (IVHS), which consist of interacting intelligent vehicles (IV) and intelligent roadside controllers. Vehicles are organized in convoy with small distances between them. All vehicles are assumed to be fully automated (throttle control, braking, steering). Proposed approaches for determining speed limits for traffic cars on the motorway using a model predictive control (MPC). The article proposes an approach to dynamic speed limit to minimize the downtime of vehicles in traffic.

Prevalence of new psychoactive substances and prescription drugs in the Belgian driving under the influence of drugs population.

Driving under the influence of drugs (DUID) is a worldwide problem. Several countries have adopted DUID legislations which prove their deterrent effect and impact on road safety. However, the use of new psychoactive substances (NPS) and prescription drugs is not known, as the applied roadside screening tests have not yet been adapted for these compounds. In this study, 558 blood samples obtained during roadside controls in Belgium (January to August 2015) after a positive Drugwipe 5S® test and 199 oral fluid (OF) samples obtained from negatively screened test pads were analyzed. The NPS positivity rate was 7% in blood, while it reached 11% in OF. NPS detected were: diphenidine, ketamine, 4-fluoroamphetamine, 2-amino-indane, methoxetamine, α-PVP, methiopropamine, a mix of 5-MAPB/5-EAPB, TH-PVP, mephedrone, methedrone, 4-methylethylcathinone, 5-MeO-DALT, 4-Acetoxy-DiPT, AB Fubinaca, FUB-JWH018, JWH020, trifluoromethylphenylpiperazine, and ethylphenidate. Moreover, 17% of blood samples (and 5% of OF) contained an analgesic drug, 10% (0.5%) a benzodiazepine/hypnotic, 5% (2%) an antidepressant, 2% (3%) an antipsychotic, 2% an antiepileptic drug, and 1% methylphenidate. The presence of NPS in the young (and predominately male) DUID population is proven. Furthermore, a high level of poly-drug use including combinations of NPS, licit, and drugs of abuse was observed. Further research concerning the development of on-site NPS detection techniques should be established. Meanwhile, the effects of combined drug use on driving ability and the physical/psychological signs after NPS use should be performed to improve the on-site DUID detection of NPS by police officers, so they can engage in blood sampling for a general unknown screening.

Efficient control of fully automated connected vehicles at freeway merge segments

This paper presents a longitudinal freeway merging control algorithm for maximizing the average travel speed of fully automated connected vehicles. Communication with a roadside unit allows the computation and transmission of optimized trajectories to the equipped vehicles. These vehicles then carry out the trajectories and resume normal operation once they cease communication with the roadside controller. A tool was developed to simulate and carry out the merging algorithm, while interfacing with the optimization software LINGO. A hypothetical merging segment was simulated to evaluate the effectiveness of the merging algorithm, and its performance is compared to conventional vehicle operation. During uncongested conditions the algorithm is able to reduce travel time, increase average travel speed and improve throughput. The capacity of the merge segment is directly related to the safe time gap selected to run the algorithm. Once capacity is reached, queuing forms on both the ramp and mainline segments upstream of the merge area. The algorithm provides safe merging operations during this congested traffic state.

Reducing the risk of rear-end collisions with infrastructure-to-vehicle (I2V) integration of variable speed limit control and adaptive cruise control system

ABSTRACTObjective: Adaptive cruise control (ACC) has been investigated recently to explore ways to increase traffic capacity, stabilize traffic flow, and improve traffic safety. However, researchers seldom have studied the integration of ACC and roadside control methods such as the variable speed limit (VSL) to improve safety. The primary objective of this study was to develop an infrastructure-to-vehicle (I2V) integrated system that incorporated both ACC and VSL to reduce rear-end collision risks on freeways.Methods: The intelligent driver model was firstly modified to simulate ACC behavior and then the VSL strategy used in this article was introduced. Next, the I2V system was proposed to integrate the 2 advanced techniques, ACC and VSL. Four scenarios of no control, VSL only, ACC only, and the I2V system were tested in simulation experiments. Time exposed time to collision (TET) and time integrated time to collision (TIT), 2 surrogate safety measures derived from time to collision (TTC), were used to evaluate safety issues associated with rear-end collisions. The total travel times of each scenario were also compared.Results: The simulation results indicated that both the VSL-only and ACC-only methods had a positive impact on reducing the TET and TIT values (reduced by 53.0 and 58.6% and 59.0 and 65.3%, respectively). The I2V system combined the advantages of both ACC and VSL to achieve the most safety benefits (reduced by 71.5 and 77.3%, respectively). Sensitivity analysis of the TTC threshold also showed that the I2V system obtained the largest safety benefits with all of the TTC threshold values. The impact of different market penetration rates of ACC vehicles in I2V system indicated that safety benefits increase with an increase in ACC proportions.Conclusions: Compared to VSL-only and ACC-only scenarios, this integrated I2V system is more effective in reducing rear-end collision risks. The findings of this study provide useful information for traffic agencies to implement novel techniques to improve safety on freeways.

Analysis of the prevalence of medicines and psychoactive substances among drivers in the material of the Department of Forensic Medicine at the Medical University of Bialystok.

To evaluate the prevalence of medicines and psychoactive substances in the blood of drivers. The data, recorded in 2010-2011, was comprised of 274 blood samples of sober drivers (269 men and 5 women). 126 drivers within the group died immediately on the spot (mean age 29.7 years, range 19-53 years), 31 drivers survived the accident (mean age 32.4 years, range 24-69 years), and 117 drivers were stopped for traffic control (mean age 26.4 years, range 17-49 years). ELISA immuno-enzymatic blood tests detecting medicines and psychoactive substances were performed by the Neogen company. The presence of the tested substances was confirmed by gas chromatography and liquid chromatography with a mass detector (GC/MS and LC/MS). From the total number of 274 individuals, the presence of psychoactive substances was found in 132 cases, which accounted for 48.2% of all subjects. The drivers found to be under the influence of medicines and psychoactive substances were most often stopped for a roadside survey, among whom the percentage of positive results was 92.3% (108 cases out of 117 subjects). Among the total number of positive findings the psychoactive substances used, alone or in combination with other agents, were tetrahydrocannabinols (42.4%), amphetamines (26.5%), opiates (25.7%) and benzodiazepines (15.1%), and their concentration in the blood did not exceed toxic levels. In the group of psychoactive substances most often used, either alone or in combination with other agents, there were tetrahydrocannabinols, whose high percentage of positive results in drivers stopped for a roadside control may be explained by commissioning studies on early screening. Concentrations of the substances in most cases did not exceed toxic levels. Roadside examinations, on the basis of their alcohol-like effect, were performed primarily on male drivers.

A review of suspected cases of driving under the influence of drugs (DUID) involved in traffic accidents in Istanbul (Turkey)

Nowadays traffic accidents, which have high mortality and morbidity, are an important public health problem. The association between the use of alcohol and/or drugs by drivers and the increased risk of traffic accidents with a high risk of death and injury has been well described in the literature.This study aimed to review the incidence of cases of driving under the influence of drugs (DUID) among all cases of driving under the influence (DUI) of alcohol and/or other drugs involved in traffic accidents and to evaluate the type of the psychoactive drugs (with or without alcohol) detected in blood samples in Istanbul and its surrounding area. This study is the first investigation on the subject of DUID cases in Turkey.The reports of the Istanbul Toxicology Department of the Council of Forensic Medicine (Turkey) on suspected DUID cases involved in traffic accidents between 1 July 2010 and 30 June 2011 were retrospectively reviewed for alcohol and/or drug use.Alcohol analysis was requested in 4274 suspected DUI cases, whereas drug along with alcohol analysis was requested in only 91. The rate of suspected DUID cases (n = 91) among the suspected DUI cases (n = 4274) was only 2.1% and in this study, we evaluated only the DUID cases in detail. Alcohol was present in 44% of suspected DUID cases. Psychoactive drugs were present in 15.4% of cases. The incidence among 46 confirmed DUID cases was found to be 17.4% for cannabis, 8.7% for benzodiazepines, 4.3% for barbiturates, 4.3% for antidepressants, 2.2% for cocaine and 2.2% for amphetamines.Although there is a zero-tolerance approach for DUID in the Turkish regulations, it is not well recognised and not inspected by police and legal authorities who are responsible for taking measures in traffic accidents and for routine traffic controls in Turkey. It is concluded that psychoactive drugs should be checked as well as alcohol in all traffic accident cases and roadside controls.

Optimal routing for automated highway systems

We present a routing guidance approach that can be used in Automated Highway Systems (AHS). We consider automated highway systems in which intelligent vehicles organised in platoons drive to their destination, controlled by a hierarchical control framework. In this framework there are roadside controllers that provide speed and lane allocation instructions to the platoons. These roadside controllers typically manage single stretches of highways. A collection of highways is then supervised by so-called area controllers that mainly take care of the route guidance instructions for the platoons and that also coordinate the various roadside controllers in their area. In this paper we focus on the optimal route choice control problem for the area controllers. In general, this problem is a non-linear integer optimisation problem with high computational requirements, which makes the problem intractable in practice. Therefore, we first propose a simplified but fast simulation model to describe the flows of platoons in the network. Next, we show that the optimal route choice control problem can be approximated by a mixed-integer linear problem. Later, we describe a new METANET-like model to describe the flow of platoons in the AHS. With a simple case study we illustrate that both approaches result in a balanced trade-off between optimality and computational efficiency.

Driving Under the Influence of Cannabis

"Driving under the influence of drugs" (DUID) has a large impact on the worldwide mortality risk. Therefore, DUID legislations based on impairment or analytical limits are adopted. Drug detection in oral fluid is of interest due to the ease of sampling during roadside controls. The prevalence of Δ9-tetrahydrocannabinol (THC) in seriously injured drivers ranges from 0.5% to 7.6% in Europe. For these reasons, the quantification of THC in oral fluid collected with 3 alternative on-site collectors is presented and discussed in this publication. An ultra-performance liquid chromatography-mass spectrometric quantification method for THC in oral fluid samples collected with the StatSure (Diagnostic Systems), Quantisal (Immunalysis), and Certus (Concateno) devices was validated according to the international guidelines. Small sample volumes of 100-200 μL were extracted using hexane. Special attention was paid to factors such as matrix effects, THC adsorption onto the collector, and stability in the collection fluid. A relatively high-throughput analysis was developed and validated according to ISO 17025 requirements. Although the effects of the matrix on the quantification could be minimized using a deuterated internal standard, and stability was acceptable according the validation data, adsorption of THC onto the collectors was a problem. For the StatSure device, THC was totally recovered from the collector pad after storage for 24 hours at room temperature or 7 days at 4°C. A loss of 15%-25% was observed for the Quantisal collector, whereas the recovery from the Certus device was irreproducible (relative standard deviation, 44%-85%) and low (29%-80%). During the roadside setting, a practical problem arose: small volumes of oral fluid (eg, 300 μL) were collected. However, THC was easily detected and concentrations ranged from 8 to 922 ng/mL in neat oral fluid. A relatively high-throughput analysis (40 samples in 4 hours) adapted for routine DUID analysis was developed and validated for THC quantification in oral fluid samples collected from drivers under the influence of cannabis.

Prevalence of psychoactive substances, alcohol, illicit drugs, and medicines, in Spanish drivers: A roadside study

Following population, geographic, road type and time criteria, Spain has carried out random, roadside controls of 3302 representative sample of Spanish drivers, including saliva analysis for 24 psychoactive substances and alcohol breath tests. The 81.4% of the drivers were male, with an average age of 34.8±11.8 (mean±SD). The 17% of the drivers were found to be positive to any of the substances analysed. The 6.6% of the drivers found positive to alcohol (>0.05mg/l in breath), 11% were found positive to any illicit drug, and 2% were positive to one of the medicines analysed. Some drivers were positive in more than one substance. The most common illicit drugs among Spanish drivers were cannabis (7.7%), or cocaine (3.5%), either alone or combined with other substances. The most prevalent medicines were the benzodiazepines (1.6%). As a tendency, higher figures for positive cases were observed among males than in females (being statistically significant the differences for alcohol, cannabis and cocaine). Alcohol and cocaine positive cases were more frequently found among drivers of urban roads. Alcohol positive cases (alone, >0.05mg/l), were more likely found as age increase (OR=1.02), those driving in urban roads (OR=2.13), and driving at any period than weekdays, while alcohol+drugs cases were more likely found among males (OR=2.819), those driving on urban road (OR=2.17) and driving at night periods. Finding a medicines positive case was more likely as elder the driver was (OR=1.05). There have been differences in the prevalence of positive cases of alcohol, cannabis and cocaine, in relation to the period of the week: in three cases the highest prevalence seen in night time. This study shows the high prevalence of psychoactive substances and alcohol in Spanish drivers, mainly illicit drugs (cannabis). This question requires a response from the authorities and from society, with an integral and multi-disciplinary approach that can heighten the population's awareness of the risks of driving under the influence of certain substances.

Traffic Management for Automated Highway Systems Using Model-Based Predictive Control

We present an integrated traffic management and control approach for automated highway systems (AHS). The AHS consist of interacting roadside controllers and intelligent vehicles that are organized in platoons with short intraplatoon distances and larger distances between platoons. All vehicles are assumed to be fully automated, i.e., throttle, braking, and steering commands are determined by an automated onboard controller. The proposed control approach is based on a hierarchical traffic control architecture for AHS, and it also takes the connection and transition between the nonautomated part of the road network and the AHS into account. In particular, we combine dynamic speed limits and lane allocation for the platoons on the AHS highways with access control for the on-ramps using ramp metering, and we propose a model-based predictive control approach to determine optimal speed limits and lane allocations, as well as optimal release times for the platoons at the on-ramps. To illustrate the potential of the proposed traffic control method, we apply it to a simple simulation example.

Optimal Routing for Intelligent Vehicle Highway Systems Using Mixed Integer Linear Programming

We present a routing guidance approach that can be used in Intelligent Vehicle Highway Systems (IVHS). We consider IVHS consisting of automated highway systems on which intelligent vehicles organized in platoons drive to their destination, controlled by a hierarchical control framework. In this framework there are roadside controllers that provide speed and lane allocation instructions to the platoons. These roadside controllers typically manage single stretches of highways. A collection of highways is then supervised by so-called area controllers that mainly take care of the route guidance instructions for the platoons and that also coordinate the various roadside controllers in their area. In this paper we focus on the optimal route choice control problem for the area controllers. In general, this problemis a nonlinear integer optimization problemwith high computational requirements, whichmakes the problem intractable in practice. Therefore, we first propose a simplified but fast simulation model to describe the flows of platoons in the network. Next, we show that the optimal route choice control problem can be approximated by a linear or a mixed integer linear problem. With a simple case study we illustrate that this results in a balanced trade-off between optimality and computational efficiency.

Correlation of Δ 9-tetrahydrocannabinol concentrations determined by LC–MS–MS in oral fluid and plasma from impaired drivers and evaluation of the on-site Dräger DrugTest ®

Oral fluid (collected with the Intercept ® device) and plasma samples were obtained from 139 individuals suspected of driving under the influence of drugs and analyzed for Δ 9-tetrahydrocannabinol (THC), the major psychoactive constituent of cannabis, using a validated quantitative LC–MS–MS method. The first aim of the study was to investigate the correlation between the analytical data obtained in the plasma and oral fluid samples, to evaluate the use of oral fluid as a ‘predictor’ of actual cannabis influence. The results of the study indicated a good accuracy when comparing THC detection in oral fluid and plasma (84.9–95.7% depending on the cut-off used for plasma analysis). ROC curve analysis was subsequently used to determine the optimal cut-off value for THC in oral fluid with plasma as reference sample, in order to ‘predict’ a positive plasma result for THC. When using the LOQ of the method for plasma (0.5 ng/mL), the optimal cut-off was 1.2 ng/mL THC in oral fluid (sensitivity, 94.7%; specificity, 92.0%). When using the legal cut-off in Belgium for driving under the influence in plasma (2 ng/mL), an optimal cut-off value of 5.2 ng/mL THC in oral fluid (sensitivity, 91.6%; specificity, 88.6%) was observed. In the second part of the study, the performance of the on-site Dräger DrugTest ® for the screening of THC in oral fluid during roadside controls was assessed by comparison with the corresponding LC–MS–MS results in plasma and oral fluid. Since the accuracy was always less than 66%, we do not recommend this Dräger DrugTest ® system for the on-site screening of THC in oral fluid.

SPVD: A magnetic vehicle detection system using a low power magnetometer

The Self Powered Vehicle Detector (SPVD) is a motor vehicle detection system, presently under development, that detects a vehicle's presence by measuring its magnetic signature in the roadway. An optimized two axis Brown fluxgate magnetometer is used as the transducer with a digital nulling loop to perform sensor offset nulling and logic functions. An FM telemetry link containing three encoded tones conveys the roadway emplanted SPVD vehicle presence and device status information to a roadside control unit which may interface with other traffic control systems. A minimum one year operational lifetime is anticipated in a roadway with a 20,000 vehicles/day traffic flux.

A note on tape recording of stadia observations

Abstract A large part of the work of the surveyors of the Soil Conservation Service of New South Wales involves the production of large-scale topographical plans. Usually, the areas are too small and too scattered for the economical use of photogrammetrical methods and stadia survey is much used for the larger scale detail and contour surveys required for roadside erosion control projects and for vineyard design and layout. Stadia surveys take such a large part of the surveyors' time that continuing thought is given to possibilities of reducing the time and cost of the work while maintaining all the required accuracy. The latest development, which was originated and developed by Mr. B. C. Rolfe, is the use of a transistorised tape recorder for recording the field observations.