Arboricultural Assessment of Street Trees in Colombo City, Sri Lanka

Roadside trees are beneficial for providing ecological services, such as heat absorbance, natural air conditioning, and reducing GHG emissions in urban landscapes. This study examines the tree structure, species composition, species diversity, and some field observations (i.e. tree structural defects and disorders) on roadside trees in Colombo City. The vegetation parameters, such as diameter-at-breast height (DBH), tree height, and crown radius were measured in each tree. Purposive random sampling was adapted to invent street trees along High-level Road (Nugegoda to Tummulla junction), Bauddhaloka Mawatha (Tummulla junction to Borella Cemetery junction),Viharamahadevi Park circle and suburbs, Ananda Coomaraswamy Mawatha-Sri Jayawardanapura Mawatha (Kollupitia to Rajagiriya), Jawatta Road, Torinton Avenue and Keppitipola road. A total of 1458 street trees belonging to 92 species, 71 genera and 33 families were recorded along the roadways of Colombo City expanding ca. 20 km in length. Average 41±18 trees were located per kilometer. The survey shows that 64% of the species were exotic and 36% were indigenous species, reflecting the trend towards planting more exotic tree species in streets in recent past. The most dominant street trees were Albizia saman [% Relative Density (RD)=8; % Relative Basal Area (RBA)=34, % Relative Crown Cover (RCC)=30] and Peltophorum pterocarpum [% RD=11; % RBA=16; % RCC=19]. The highest number of trees was recorded from Public Library to Town Hall via Anagarika Dharmapala Mawatha (69 trees/km and 36 spp./km) and the most diverse tree species composition was found along Marcus Fernando Mawatha (66 trees/km and 52 spp./km) at Viharamahadevi Park circle. In conclusion, maintaining urban forest inventories, silvicultural managing of street trees from Ficus invasion, and introducing suitable native trees viz., Lagerstroemia speciose (Murutha), Pongamia pinnata (Magul-Karanda), Barringtonia asiatica (Mudilla) and Phyllanthus emblica (Nelli) for future tree planting areas will be recommended.Keywords: Street trees, Forest inventory, Silvicultural management, Colombo cit

Suitability of Government Bid Evaluation Procedure for Building Projects in Sri Lanka

In Sri Lanka, a Contractor is selected through a bid evaluation procedure in construction projects and this is be a crucial step in the implementation of the project. The most frequently used bid evaluation procedure in Sri Lanka is the Government Bid Evaluation Procedure (GBEP), the Government being the client in most of the projects. Although GBEP is referred to in government publications, it has so far not been analysed in detail. This study therefore was conducted to identify the suitability of GBEP to local building projects. Firstly, a literature synthesis and a desk study were carried out. The degree of use of GBEP identified from the literature synthesis was validated through semi structured interviews which also identified the advantages, disadvantages and limitations of GBEP. The analysis reveals that a well-defined procedure, proper documentation, possibility of selecting the lowest evaluated bid are the major advantages of GBEP while the absence of a minimum eligibility criteria for preliminary bid evaluation, adjustments done by the evaluator, low accuracy of the Engineer’s Estimate and non-consideration of the optimum bid are its major disadvantages and/or limitations. Suggestions are made to overcome the disadvantages and limitations. Flexibility on ICTAD registration, making allowance for discounts for variations, introduction of standard formats for reporting and prohibition of adjustments by the evaluator will enhance the transparency and accountability of GBEP.International Council for Research and Innovation in Building and Construction (CIB

Transaction ccosts of green office building construction in Sri Lanka

Although the concept of Green Building is popular in other countries, it is not yet so in Sri Lanka as no clear identification of the transaction cost of green buildings has so far been made. Given the expanding scope of construction of office buildings in Sri Lanka, it has become important to differentiate between the transactions costs of green buildings from those of conventional buildings. Hence this research is aimed at studying the transaction costs of green office buildings in Sri Lanka. A literature synthesis was carried out to learn about the green building concept and the benefits of green buildings. Identification of the transaction cost components was done through three preliminary interviews and two case studies conducted through semi structured interviews that were aimed at comparing the cost components of each building type with those of the other type. The findings revealed that the transaction costs of green buildings in Sri Lanka relates to costs incurred for preliminary studies, managing the designs, gaining knowledge on green certified material, technical advice, documentation and commissioning for LEED certificates and quality checking by obtaining the services of green consultants. Hence, the state agencies need to ensure that green material is available at discounted prices, take steps to present awards to professionals involved in green building and conduct seminars for the benefit of these professionals. It is also recommended that the Green Building Council should lower its commissioning fees to encourage the developers to obtain green certificates so that the concept of Green Building in Sri Lanka is promoted

FACTORS AFFECTING THE INDOOR ENVIRONMENTAL QUALITY IN SRI LANKA: GREEN VS. CONVENTIONAL HOTEL BUILDINGS

The hotel building sector is now using sustainable design and construction practices thereby helping to prevent environmental pollution. Green building practices are capable of promoting a healthy and comfortable indoor environment for hotel occupants (including guests and staff). Some criticism has been made by occupants of green buildings on the accuracy of the certification process and the performance of LEED certified buildings. Therefore, this study is aimed at identifying the key factors affecting the Indoor Environmental Quality (IEQ) of green buildings compared to that of conventional hotel buildings by evaluating building performance. Firstly, a literature survey was conducted to identify the importance of IEQ in green buildings and the methods of evaluating IEQ performance. Subsequently, key and sub factors relating to IEQ performance identified from the literature review were validated through expert interviews. A questionnaire survey and semi structured interviews were used as data collection techniques by making use of two green buildings and two conventional buildings. The data was analysed using Mann-Whitney U-test and “Nvivo 10” software. The analysis revealed that green hotels provide an overall IEQ performance that is higher than that of conventional hotels. However, factors such as lighting, acoustics and the degree of personal control that occupants have on the indoor environment were comparatively less satisfactory in green hotels. The paper also discussed the reasons for the low satisfaction of IEQ in respect of these factors. Finally this study confirms that the hotel industry needs to consider a climate responsive design to ensure a better IEQ and pay attention to post occupancy evaluation throughout the life cycle of a building

Simulation of mobile robot navigation with sensor fusion on an uneven path

This paper describes the navigation of a two-wheel drive mobile robot along a predefined path under uneven road conditions where it cannot solely rely on encoders, GPS or an accelerometer individually. There are conditions when low friction or slippery ground surfaces such as sandy paths and pits cause one or both encoders to halt or rotate less as the robot moving forward. Areas covered with clouds, trees or structures can block GPS signals. Sudden pickups and halts give false information from accelerometers. Therefore Kalman filter based sensor fusion algorithm is implemented in order to get the best position estimation for the mobile robot using above sensor outputs. The Special feature of this algorithm is that it includes a simple method to overcome the effects of encoder errors due to the slipping of wheels of the mobile robot, which does not require complex computations to additional measurement units to directly measure the slipping of the wheels of the robot. Finally the validity of the proposed algorithm is demonstrated via simulation

Fossils on Mars: A "Cambrian Explosion" and "Burgess Shale" in the Lake Beds of Gale Crater?

An array of formations resembling the fossilized remains of Ediacaran and Cambrian fauna and other marine organisms have been observed embedded atopsediments in the dried lake beds of Gale Crater, Mars. Specimens similar and diverse in morphology have been found together and upon adjacent and nearbyrocks and mudstone. These include forms morphologically similar to polychaete and segmented annelids, tube worms, "Kimberella,” crustaceans, lobopods,chelicerates, Haplophrentis carinatus, and the “ice-cream-cone-shaped” “Namacalathus” and “Lophophorates” and other biomineralized metazoans. Allspecimens may have dwelled in a large body of water and fossilized/mineralized following the rapid receding of these waters. Statistical quantitative micro- andmacro- morphological comparisons with analog organisms from Earth support the fossil-hypothesis. It is not likely so many similar and diverse specimens, side byside, oriented differently, some on top of each other, were fashioned via abiogenic forces such as wind, mineralization, crystallization, dried mud, or water-erosionscenarios as there are no terrestrial abiogenic analogs. Interplanetary transfer of life may explain the parallels with Earth. Collectively these putative fossils mayrepresent the equivalent of a “Cambrian Explosion” and the remnants of Martian organisms that long ago flourished in the lakes and inland seas of Gale Crater (PDF) Fossils on Mars: A "Cambrian Explosion" and "Burgess Shale" in the Lake Beds of Gale Crater?. Available from: https://www.researchgate.net/publication/365926923_Fossils_on_Mars_A_Cambrian_Explosion_and_Burgess_Shale_in_the_Lake_Beds_of_Gale_Crate