Monitor Lizards Research Articles

Advances in Clinical Toxicology depend on Ecotechnology

The oldest enriched habitat of the Banka-Siphon-Dam (BSD) of Banka River (BR) attached to Eden Canal (EC) of Damodar River (DR), Kanchannagar, Burdwan, West Bengal India, covering a 3-5 sq km area with different flora- and faunal diversity with agricultural fields and dense vegetation forty-five years ago. But it was decreasing gradually up to December 2019 due to massive visitors or tourists, picnic parties with large sound systems, irregular fishing, killing wild animals, cutting the trees, disturbing and catching different animals including migratory birds, unethical human behaviors, and urbanization nearby badly affected on ‘Advances in Clinical Toxicology’. On the other hand, the Covid-lockdowns also impacted the ecosystem health during the pandemic coronavirus-disease (COVID-19), it has also faced social and economic challenges among the communities, and health systems-“the invisible patients”, due to hampering truism and education, and suspicious killing or catch or death of grey-coloured water monitor lizards, fishing cats, civet cats, and barn owls, and even migratory birds also. And has lost the ecological balance of water, land and vegetation (micro bio-climate) with an increased viper snake, rodent population, etc. And adversely affect the environment (Water, Sanitation and Ecology) and societal problems. To overcome, it is therefore, augments and confirms that propagation of the artificial nests, awareness, plantation of different fruits plants, and cultivations would be beneficial to do away with the rodent menace primarily, and inhibit the damage and economic losses, without putting any severe implications on the sustainability of pisciculture-fishery agro-ecosystems of the “Banka-Siphon Eden-Canal of Damodar May be Develop as ‘Biodiversity-Biomedicines-Hub for Advances in Clinical Toxicology Depend on Eco-technology’ Improving World Policy”. And the perfect ecological balance of water, land and vegetation may develop any ‘Future-Socioeconomically-Ecological-Tourist-Hub with Advances in Clinical Toxicology Eco-Technology Hub’

Sightings of the Common Monitor Lizard, Varanus bengalensis in Sirohi District, Rajasthan, India

Sightings of the Common Monitor Lizard, Varanus bengalensis in Sirohi District, Rajasthan, India

Wild Life Hazard Management through Wild Animal Control System at Airport

This study aims to analyze systemm control of wild animals and the process of solving problems of controlling wild animals at Taufik Kiemas Airport, Pesisir Barat, Lampung Province based on public perception.This research was conducted at Taufik Kiemas Pesisir Barat Airport, Lampung Province in August 2022. In this study, the researcher used a descriptive type of research with a qualitative approach. This study uses one data source, namely primary data sources obtained through surveys. The sampling method is purposive sampling. In this study there were 19 people who became the research sample. The data analysis technique used descriptive qualitative analysis which attempted to describe the nature of the problems studied which were carried out in the field at the time of data collection. The results showed that the presence of wild animals such asbobcats, monkeys, wild boars, monitor lizards, snakes, various birds, monkeys and othersin Banfrom Taufik Kiemas Airport, West Coast of Lampung Province. Therefore it is necessary to create a special unit that handles the presence of wild animals at the airport and regulations are needed that are understood by all employees. In an emergency caused by wild animals, officers must understand how to mitigate the risk, so training and socialization are needed in understanding the presence of wild animals at airports.

The Water Monitor Lizard Survey in Prince of Songkla University, Pattani Campus, Pattani Province

The Water Monitor Lizard Survey in Prince of Songkla University, Pattani Campus, Pattani Province

PEMBERDAYAAN DAN PENINGKATAN KAPASITAS KELEMBAGAAN MASYARAKAT DESA MELALUI AGROWISATA BERBAHASA INGGRIS

Agribusiness utilizes inorganic waste that can be recycled to produce selling points such as basket bags from plastic waste and dolls from cloth waste. There is a superior product in this business unit, namely processed Jenitri seeds which are processed into handicrafts. Jenitri seeds are not only used as an ornamental tool. In certain beliefs, the work of Jenitri seeds is used as a worship tool and a medical device. Therefore, Jenitri seeds have a fairly high selling value compared to other handicrafts because of their various functions. Adiluhur Tourism Village is a village that is currently under development as a tourist spot with the name Kebumen English Tourism Village (KWIK) and is located in Adiluhur Village, Kec. Adimulyo, Kab. Kebumen. There are 3 business units that are superior and are still in the development stage, namely business units in the fields of tourism (agro-tourism), agriculture (agriculture), and handicrafts (agribusiness). Currently, the primary superior unit in Adiluhur Tourism Village is a business unit in the tourism sector. Agrotourism is managed by CV in collaboration with BUMDes (Village Owned Enterprise) Mulia Jaya. The tour featured in this unit is an introduction to several types of captive animals (various types of snakes, monitor lizards, sea urchins, iguanas, mongooses, Australian geckos, crocodiles, alligator fish, and many more) as well as a museum containing ancient agricultural tools (bronze spoon, harrows, sickles, hoes, nails, antique lamps, and many more). The potential that is being developed in this unit is outbound with the target visitor being Elementary Schools. Not only that, the agro-tourism manager plans to work with the BKSDA (Natural Resources Conservation Center) in caring for the animals in the unit.

Hunter-gatherers in labyrinth karst: An Early Holocene record from Gunung Sewu, Java

Gua Mandung is an inland prehistoric site in Gunung Sewu karst area of central Java, Indonesia. This area is rich in valleys and corridors which make up Gunung Sewu's distinct labyrinth-like landscape. For Java, Gunung Sewu is known to have a relatively harsh environment with limited access to permanent water sources and a short wet season. However, here we report evidence of occupation at the site of Gua Mandung since at least 11,073 cal BP. An abundance of terrestrial fauna remains alongside numerous bone tools with differing functionalities suggests that these early cave dwellers applied well-developed subsistence strategies to maximise the available resources. Gua Mandung records continuous exploitation of small to large terrestrial fauna including monkeys, porcupine, deer, pig, cattle, rat, snake, and monitor lizard. The site's proximity to nearby lakes and a ∼ 5 km walk to the coast also provided Gua Mandung's early inhabitants with secondary aquatic resources such as fish, freshwater shells, marine shells, barnacles, crab, and sea urchin. Based on our findings from the Gua Mandung excavation, and in comparison with surrounding archaeological sites, coastal resource exploitation appears to have been a common, albeit more minor, subsistence strategy employed by the early inland communities of the Gunung Sewu karst area.

Hard ticks in Burmese amber with Australasian affinities.

Three examples of metastriate hard ticks (Ixodida: Ixodidae) with apparent affinities to modern Australasian genera are described from the mid-Cretaceous (ca. 100 Ma) Burmese amber of Myanmar. Two nymphs of Bothriocroton muelleri sp. nov. represent the oldest (and only) fossil record of this genus, living members of which are restricted to Australia and predominantly feed on monitor lizards, snakes and echidnas. A female of Archaeocroton kaufmani sp. nov. shares its basis capitulum shape with the tuatara tick Archaeocroton sphenodonti (Dumbleton, 1943), the only extant member of this genus and an endemic species for New Zealand. The presence of 2 Australasian genera in Burmese amber is consistent with a previous record of an Ixodes Latreille, 1795 tick from this deposit which resembles Australian members of this genus. They further support an emerging hypothesis that fauna of the amber forest, which may have been on an island at the time of deposition, was at least partly Gondwanan in origin. A revised evolutionary tree for Ixodida is presented compiling data from several new Burmese amber ticks described in the last few years.

MATING BEHAVIOR AND BREEDING OF THE BLUE TREE MONITOR, VARANUS MACRAEI IN AN IN-COUNTRY FACILITY IN INDONESIA: A PRELIMINARY NOTE

The Blue tree monitor, Varanus macraei Böhme & Jacobs, 2001 is a tree monitor species favored by reptile keepers. Successful captive breeding was reported from hobbyists and zoos in Europe shortly after its scientific description. Meanwhile, commercial farming to supply international demands has been progressing in Indonesia. However, such successful ex-situ breeding efforts have not yet been documented or published in Indonesia thus far. Therefore, in this, study we describe for the first time the mating behavior and reproduction of a V. macraei couple in an in-country outdoor facility, which is a common husbandry practice for monitor lizard breeders in Indonesia. The male started to approach the female at the beginning of the dry season, in May, with the female showing defensive behavior towards the male, both before mating and after laying eggs, pointing to a seasonal reproductive behavior. Monitor lizards were observed being active during the daytime. Eggs were laid by mid-July 2020. Two of the six eggs laid were revealed to be fertile and hatched after about 23 weeks (5.6 months). The two hatchlings were reared in an indoor enclosure, but only one survived, which showed to be a male.

The influence of pups on aggressive interactions between smooth-coated otters and water monitor lizards in Singapore.

Smooth-coated otters (Lutrogale perspicillata) and Malayan water monitor lizards (Varanus salvator) occupy similar habitats and interact regularly in Singapore's waterways. These interactions have a range of potential outcomes and are sometimes lethal. Few formal behavioral studies exist for either species. We analyzed interactions between otters and monitor lizards by gleaning data from publicly available videos from citizen scientists to examine what factors influence aggressive and defensive behaviors and what influences vigilance in otters. Behavioral sequence analysis revealed no obvious monitor lizard behavior that predicted otter aggression toward monitors. We found that the presence and number of otter pups are positively associated with otter aggression. Otters also tended to be more vigilant in groups with more pups and more vigilant on land than water. Monitor lizards almost always displayed aggressive and defensive behaviors, regardless of whether otters were aggressive toward the lizards. These observations suggest that otters vary their aggression and vigilance levels depending on their group composition and the physical environment of their interactions with monitor lizards.

Anguimorpha as a model group for studying the comparative heart morphology among Lepidosauria: Evolutionary window on the ventricular septation.

The group Anguimorpha represents one of the most unified squamate clades in terms of body plan, ecomorphology, ecophysiology and evolution. On the other hand, the anguimorphs vary between different habitats and ecological niches. Therefore, we focused on the group Anguimorpha to test a possible correlation between heart morphology and ecological niche with respect to phylogenetic position in Squamata with Sphenodon, Salvator, and Pogona as the outgroups. The chosen lepidosaurian species were investigated by microCT. Generally, all lepidosaurs had two well-developed atria with complete interatrial septum and one ventricle divided by ventricular septa to three different areas. The ventricles of all lepidosaurians had a compact layer and abundant trabeculae. The compact layer and trabeculae were developed in accordance with particular ecological niche of the species, the trabeculae in nocturnal animals with low metabolism, such as Sphenodon, Heloderma or Lanthanotus were more massive. On the other hand athletic animals, such as varanids or Salvator, had ventricle compartmentalization divided by three incomplete septa. A difference between varanids and Salvator was found in compact layer thickness: thicker in monitor lizards and possibly linked to their mammalian-like high blood pressure, and the level of ventricular septation. In summary: heart morphology varied among clades in connection with the ecological niche of particular species and it reflects the phylogenetic position in model clade Anguimorpha. In the absence of fossil evidence, this is the closest approach how to understand heart evolution and septation in clade with different cardiac compartmentalization levels.

Front cover

The cover image is based on the Original Article Histological and histochemical characteristics of the oral, pharyngeal and accessory digestive organs in the water monitor lizard (Varanus salvator) from Thailand by Nattawut Srichairat et al., https://doi.org/10.1111/ahe.12846.

New records of Amblyomma gervaisi from Pakistan, with detection of a reptile-associated Borrelia sp.

Ticks are hematophagous ectoparasites of terrestrial and semi-aquatic vertebrates that may transmit microorganisms to their hosts. Spirochetes of the genus Borrelia are common in ticks and an incipient group has been identified in association with reptiles and their tick parasites. To overcome the knowledge deficit, this study aimed to morphologically and molecularly identify ticks infesting wild lizards and to molecularly assess Borrelia spp. associated with these ticks in Pakistan. For this purpose, free-ranging monitor lizards (Varanus bengalensis) from Khyber Pakhtunkhwa province, Pakistan, were examined for tick infestations. A total of 776 ticks were collected from 36/63 lizards, resulting in a prevalence of 57% (95% CI 44.7-69.3%), overall mean intensity of 21.5 (95% CI 18.9-24.1) ticks per infested lizard, and overall mean abundance of 12.3 (95% CI 9.25-15.4) ticks per examined lizard. All ticks were morphologically identified as Amblyomma gervaisi. The morphological identification of the ticks was molecularly confirmed through sequencing fragments of the mitochondrial 16S rRNA gene. In addition, a fragment of nuclear second internal transcribed spacer (ITS2) was generated for the first time for A. gervaisi. Phylogenetic analysis inferred from tick 16S rRNA gene partial sequences predicted a close evolutionary relationship of the collected A. gervaisi ticks with conspecific sequences from India, which shared 94.5% identity. Through two PCR assays targeting fragments of the borrelial genes, 16S rRNA and flaB, 19 (18%) out of 108 ticks yielded borrelial DNA. Phylogenetic analyses inferred from DNA sequences of the two borrelial genes revealed that the Borrelia sp. from A. gervaisi detected in this study belonged to the reptile-associated Borrelia group (REP). This is the first molecular report of ticks infesting monitor lizards and associated Borrelia sp. in Pakistan. The preliminary phylogenetic analyses of A. gervaisi may assist in understanding the molecular epidemiology of Amblyomma spp.

NESTING PATTERN AND NEST PREDATORS OF SOME RESIDENT BIRDS OF ECOPARK, AN URBAN PARK IN KOLKATA, WEST BENGAL, INDIA

This Study was conducted from May 2020 to April 2022 at an urban park name Ecopark, located in Kolkata. A total of 116 nests of 38 birds were observed in this study area. Out of these 116 bird nests, 82 bird nests were found to have well developed young, while the other 34 were discovered to be unsuccess due to various reasons. Common Mynas (11) nests were found most. 8 types of nesting structures were observed during this survey namely Deep cup nest, Shallow cup nest, Hole nest, Platform nest, Dome shaped nest, Flat shaped nest, Hanging nest and pear-shaped nest. Hole nest (11) was the most visible nest in this study. Birds were seen nesting lowest on the surface of the water 0 ft to highest over 40 ft height. Storms, heavy rains, human activities, birds of prey, monitor lizards, snakes, rats, ants were indicated as the nests, chicks and birds egg damager.

Wild Food: Plants, Fish and Small Animals on the Menu for Early Holocene Populations at al-Khiday, Central Sudan

AbstractAl-Khiday, located on the bank of the White Nile in Sudan, offers an exceptionally preserved stratigraphic sequence, providing a unique opportunity to use organic residue analysis to investigate diet and subsistence during the Khartoum Mesolithic and the Early Neolithic, a period of nearly 3500 years (7000–4500 cal BC). While the vast and diverse Mesolithic fish assemblage indicates a strong reliance on products from aquatic habitats, floodplains, vegetated marshes, and open water, results from the lipid residue analysis suggest that the fish were not cooked in ceramic pots, but consumed in other ways. Rather, pots were more specialized in processing plants, including wild grasses, leafy plants, and sedges. These results, confirmed by experimental analysis, provide, for the first time, direct chemical evidence for plant exploitation in the Khartoum Mesolithic. Non-ruminant fauna (e.g., warthog) and low lipid-yielding reptiles (e.g., Adanson’s mud turtle and Nile monitor lizard), found in significant numbers at al-Khiday, were likely also cooked in pots. There is little evidence for the processing of wild ruminants in the Mesolithic pots, suggesting either that ruminant species were not routinely hunted or that large wild fauna may have been cooked in different ways, possibly grilled over fires. These data suggest sophisticated economic strategies by sedentary people exploiting their ecological niche to the fullest. Pottery use changed considerably in the Early Neolithic, with ruminant products being more routinely processed in pots, and while the exploitation of domesticates cannot be confirmed by a small faunal assemblage, some dairying took place. The results provide valuable information on Early and Middle Holocene lifeways in central Sudan.

The efficacy of computed tomography scanning versus surface scanning in 3D finite element analysis.

Finite element analysis (FEA) is a commonly used application in biomechanical studies of both extant and fossil taxa to assess stress and strain in solid structures such as bone. FEA can be performed on 3D structures that are generated using various methods, including computed tomography (CT) scans and surface scans. While previous palaeobiological studies have used both CT scanned models and surface scanned models, little research has evaluated to what degree FE results may vary when CT scans and surface scans of the same object are compared. Surface scans do not preserve the internal geometries of 3D structures, which are typically preserved in CT scans. Here, we created 3D models from CT scans and surface scans of the same specimens (crania and mandibles of a Nile crocodile, a green sea turtle, and a monitor lizard) and performed FEA under identical loading parameters. It was found that once surface scanned models are solidified, they output stress and strain distributions and model deformations comparable to their CT scanned counterparts, though differing by notable stress and strain magnitudes in some cases, depending on morphology of the specimen and the degree of reconstruction applied. Despite similarities in overall mechanical behaviour, surface scanned models can differ in exterior shape compared to CT scanned models due to inaccuracies that can occur during scanning and reconstruction, resulting in local differences in stress distribution. Solid-fill surface scanned models generally output lower stresses compared to CT scanned models due to their compact interiors, which must be accounted for in studies that use both types of scans.

Histological and histochemical characteristics of the oral, pharyngeal and accessory digestive organs in the water monitor lizard (Varanus salvator) from Thailand.

Srichairat, N., Taksintum, W., & Chumnanpuen, P. (2022). Histological and histochemical characteristics of the oral, pharyngeal and accessory digestive organs in the water monitor lizard (Varanus salvator) from Thailand. Anatomia Histologia Embryologia, 51, https://doi.org/10.1111/ahe.12846. The water monitor lizard (Varanussalvator) is largely distributed in Southeast Asia, especially Thailand, which the microanatomical structure studies on this particular species have been limited. Therefore, the purpose of this study is to examine and describe the oral, pharyngeal and accessory digestive organs' histological and histochemical characteristics. Histological and histochemical examinations were performed on the two specimens (male and female). The majority of V.salvator oral, pharyngeal and accessory digestive organs are similar to those of other vertebrates, according to the results of the histological investigation. However, several unique characteristics have been observed, such as the dentine lamella (plicidentine fold) at the tooth root structure was discovered to be attached to the jaw bone, the absence of lingual papillae and taste buds on the tongue, and the absence of inner surface folding structures in the gallbladder. Regarding mucin histochemical investigation, acid and neutral mucins were discovered in the pharyngeal glands of V.salvator, whereas only acid mucin was found in the mandibular salivary glands. This study reveals the histological and histochemical characteristics of V.salvator oral, pharyngeal and accessory digestive organs, which could be employed to improve digestive tract function, as well as the necessity of understanding animal digestive processes.

Novel Sources of Bioactive Molecules: Gut Microbiome of Species Routinely Exposed to Microorganisms.

Simple SummaryThe majority of antibiotics available in the market are produced by bacteria isolated from soil. However, the low-hanging fruit has been picked; hence, there is a need to mine bacteria from unusual sources. With this in mind, it is important to note that animals and pests, such as cockroaches, snake, crocodiles, water monitor lizards, etc., come across pathogenic bacteria regularly, yet flourish in contaminated environments. These species must have developed methods to defend themselves against pathogens. Besides the immunity they may confer, bacteria associated with animals/pests may offer a potential source of novel antibacterial agents. This paper discusses the current knowledge of bacteria isolated from land and marine animals with antibacterial properties and proposes untapped sources for the isolation of bacteria to mine potentially novel antibiotic molecules.The development of novel bioactive molecules is urgently needed, especially with increasing fatalities occurring due to infections by bacteria and escalating numbers of multiple-drug-resistant bacteria. Several lines of evidence show that the gut microbiome of cockroaches, snakes, crocodiles, water monitor lizards, and other species may possess molecules that are bioactive. As these animals are routinely exposed to a variety of microorganisms in their natural environments, it is likely that they have developed methods to counter these microbes, which may be a contributing factor in their persistence on the planet for millions of years. In addition to the immune system, the gut microbiota of a host may thwart colonization of the gastro-intestine by pathogenic and/or foreign microorganisms through two mechanisms: (i) production of molecules with antibacterial potential targeting foreign microorganisms, or (ii) production of molecules that trigger host immunity targeting foreign microorganisms that penetrate the host. Herein, we discuss and deliberate on the current literature examining antibacterial activities that stem from the gut bacteria of animals such as crocodiles, cockroaches, and water monitor lizards, amongst other interesting species, which likely encounter a plethora of microorganisms in their natural environments. The overall aim is to unveil a potential library of novel bioactive molecules for the benefit of human health and for utilization against infectious diseases.

Human-wildlife conflict along the edge of the Sundarbans mangrove forest in Satkhira, Bangladesh

This paper describes the scenario of human-wildlife conflict along the edge of the Sundarbans mangrove forest in Satkhira, Bangladesh. In and around the Sundarbans mangrove forest human-wildlife conflict occurs in the category of crop and material damage, depredation of domestic animal, human laceration and human death. The animals that were mostly involved in human-wildlife conflict are tiger, crocodile, snake and monitor lizard. Due to humanwildlife conflict, a total of 172 people and 10 tigers died during the period 1990-2018. Among the total claimed human death, 97.6% (n=168) of victims were killed by tiger, 1.7% (n=3) by crocodile and 0.6% (n=1) by snake. On the other hand, among the killed tigers, the higher proportion (80%, n=8) was male and the lower proportion (20%, n=2) was female. Most of the victims (90%) were assaulted by tigers during hours of sunlight, mainly from 10:00 am to 12:00 pm (40%) and 7:00 am to 9:00 am (25%). The generation approaching middle age (age 45-59) were most commonly assaulted (33%), but the attack was also high in 30-44 age class (26%). The attacks on different professional classes comprise honey gatherers (60%), woodcutters (22%) and fishermen (18%). Tiger attacks mostly took place in Gabura (59%, n=98), Koikhali (21%, n=35), Ramjannagar (10%, n=18), Munshiganj (7%, n=11) and others places (3%, n=6). Rested on the evidence of killed (97.6%, n=168) and wounded (78%, n=247) humans by tigers, 60% of the killed people were partially consumed while 30 % were not consumed when the bodies of victims were recovered. Departed bodies were found to have been dragged a distance of 300-800 m inside the deep forest from the initial spot of attack. Human wildlife conflict hampers the animal conservation initiatives in the natural ecosystems and poses the most serious challenges to the persistence and survival of wildlife. Therefore, there is an urgent necessity to develop a conducive environment for all concerned stakeholders to rectify the situation, and to revive their capacities in the most productive and successful way.
 Jahangirnagar University J. Biol. Sci. 10(1 & 2): 59-70, 2021 (June & December)

Sungai Larangan Sebagai Upaya Pelestarian Ikan Dan Lingkungan Berbasis Eduwisata Oleh KKN Tematik Universitas Mataram Di Desa Bilebante

Bilebante Village is one of the Green Tourism Villages located in Pringgarata Districs, Central Lombok Regency. Bilebante Village has various tourism potentials, one of which is the prohibition river. The prohibition river is a river area that has been mutually agreed upon as a place for conservation of fish and aquatic animals in the river area such as lizards, monitor lizards, snakes and so on as well as an educational-based tourist spot. Seeing this potential, the 2022 UNRAM Thematic KKN Students in Bilebante Village carried out a work program in building the prohibition river by making information boards containing awig-awig with the aim of being able to provide education regarding the importance of conservation fish and aquatic animals as well as those in the river area for visiting tourist to the prohibition river.

Use of road underpasses by mammals and a monitor lizard in eastern Australia and consideration of the prey-trap hypothesis.

Road networks continue to expand globally with predictable effects on ecological systems. Research into the effectiveness of road underpasses and overpasses for wildlife has been concentrated in North America and Europe. In Australia, most studies of underpasses have been of relatively short duration and without reference sites to give context to the measured rates of use. We studied 5–7 road underpasses at two locations in eastern Australia over 2–3 years, comparing camera trap detections of animals in underpasses with those at nearby forest sites. Three species of large macropod (wallabies and kangaroos) were frequently detected in the underpasses, with some underpasses traversed 1–4 times per week, and in many cases exceeded detections in the forest. The lace monitor (Varanus varius) was detected in all underpasses, often once per week during spring and summer, and infrequently in the forest. At each location, a different small macropod species, including one regionally threatened, showed a higher probability of detection in one underpass compared with several of the forest sites. The vulnerable koala (Phascolarctos cinereus) was detected infrequently in underpasses and in the adjoining forest. The short‐beaked echidna (Tachyglossus aculeatus) had a high probability of detection in a single underpass. The “prey‐trap hypothesis” postulates that predators will exhibit increased activity at underpasses as a consequence of prey being funneled. We found the red fox (Vulpes vulpes) had high activity in some underpasses. However, its activity coincided less than expected with the activity of the mammals most at risk to it. Our results provide no consistent support for the “prey‐trap hypothesis.” Instead, our study confirms the generic value of underpasses for a range of medium‐large mammals as well as one large reptile. Habitat adjoining underpasses exert a strong influence on their use and require greater consideration to maximize underpass use.