TERRAIN MODEL RESOLUTION EFFECT ON SIGHT DISTANCE ON ROADS

TERRAIN MODEL RESOLUTION EFFECT ON SIGHT DISTANCE ON ROADS.  Maria Castro, Alvaro Garcia-Espona, Luis Iglesias. Period. Polytech. Civil Eng., Vol. 59, No. 2 (2015), pp. 165-172.  DOI: 10.3311/PPci.7658

Abstract

Available sight distance is a key factor on road design. This research is focused on the effect of Digital Terrain Model (DTM) resolution on available sight distance. In addition, the effect of distance between calculation points along the vehicle path is also considered. The available sight distance is calculated using a Geographic Information System (GIS). Three high resolution DTMs, based on airborne LiDAR (Light Detection and Ranging), are used. Vehicle path is collected by a Global Navigation Satellite System (GNSS) mounted in a vehicle travelling along the road. Twelve combinations of DTM resolution and distance between calculation points along the vehicle path are studied. Results are statistically analysed and each case study is compared to a reference case which is considered close to reality. The analysis made shows that DTM resolution has a larger effect on the quality of the results than distance between calculation points. Practical issues are discussed.

Keywords

Available sight distance, Geographic Information System (GIS), Digital Terrain Model (DTM), Global Navigation Satellite System (GNSS), Light Detection and Ranging (LiDAR), traffic safety



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VEHICLE SPEED MEASUREMENT: COSINE ERROR CORRECTION

VEHICLE SPEED MEASUREMENT: COSINE ERROR CORRECTION. M. Castro, L. Iglesias, J. A. Sánchez. Measurement, 45 (8), 2128-2134. 2012.

Abstract

Although laser devices are commonly used to measure distances and vehicle speed in traffic safety-related studies, they suffer from a drawback known as the cosine effect. Furthermore, such traffic safety studies analyze both vehicle speed and a large amount of geographical data. As such, the development of efficient and cost-effective techniques for correcting the cosine error and managing the data involved in vehicle speed studies are needed. This paper presents an algorithm for correcting cosine error based on a Geographic Information System (GIS) that makes use of vehicle speed measurements and Global Positioning System (GPS) coordinates. An experiment using more than 350 vehicle speeds was conducted to test the algorithm, and the case study shows that controlling the quality of laser-measured speeds in order to suppress low quality data or correct measurement errors due to the cosine effect is very useful.

Highlights

► Laser devices are used to measure vehicle distance and speed in road studies.
► An algorithm, based on GIS, for correcting cosine error is presented.
► GIS use helps to manage data involved in vehicle speed studies.
► An experiment using more than 350 vehicles was conducted to test the algorithm.
► A discussion about laser location and measurement uncertainty is included.
 

Keywords

Laser; Speed models; Cosine error; Highway design; Consistency; Global Positioning System (GPS); Geographic Information System (GIS)


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OPERATING SPEED MODELS FOR TWO-LANE RURAL HIGHWAYS

OPERATING SPEED MODELS FOR TWO-LANE RURAL HIGHWAYS. Castro, M., Sanchez, J. F., Sanchez, J. A. Proceedings of the Institution of Civil Engineers-Transport,  165 (2), 107-118. 2012.

Abstract

Drivers adapt their driving to the conditions that they find. When the design corresponds to what a driver hopes to find, the route is consistent. This diminishes the likelihood of drivers making errors and carrying out uncertain manoeuvres. Most evaluations of highway geometric design consistency are based on the analysis of vehicles' speeds. This study reviewed the main models of operating speed prediction on two-lane rural highways. Models calibrated in several countries have been compared by means of their application to the study of nine highway sections located in different terrain types. Also, field measurements have been included in the comparison. The research results show the strengths and weaknesses of those models, their similarities, differences and the lack of suitability of some of them for mountainous highways. Based on them, specific recommendations about which models would be suitable for use are included. The speed profiles predicted by the Spanish model show, in general, higher values than most models calibrated in other countries.

Keywords:  mathematical modelling; roads & highways; traffic engineering


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SIGHT DISTANCE ANALYSIS OF HIGHWAYS USING GIS TOOLS

SIGHT DISTANCE ANALYSIS OF HIGHWAYS USING GIS TOOLS. Castro, M., Iglesias, L., Sánchez, J. A., Ambrosio, L. Transportation Research Part C: Emerging Technologies, 19 (6), 997-1005. 2011.

Abstract

Analyzing the distance visible to a driver on the highway is important for traffic safety, especially in maneuvers such as emergency stops, when passing another vehicle or when vehicles cross at intersections. This analysis is necessary not only in the design phase of highways, but also when they are in service. For its use in this last phase, a procedure supported by a Geographic Information System (GIS) has been implemented that determines the highway distances visible to the driver. The use of a GIS allows the sight distance analysis to be integrated with other analyses related to traffic safety, such as crash and design consistency analyses. In this way, more complete analyses could be made and costs shared. Additionally, with the procedure proposed it is possible to use data regarding the trajectory of a vehicle obtained on a highway with a Global Positioning System (GPS) device. This application is very useful when highway design data are not available. The procedure developed and its application in a case study are presented in this article.

Highlights

► A procedure for sight distance calculation when highway design data are unavailable.
► Integration of sight distance calculation with other road safety analyses.
► Sight distance calculations could use the most recent and detailed data available.

Keywords: Highway design; Sight distances; Geographic Information Systems; Terrain models; Global Positioning System

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ANALYSIS OF THE TEMPERATURE INFLUENCE ON FLEXIBLE PAVEMENT DEFLECTION

ANALYSIS OF THE TEMPERATURE INFLUENCE ON FLEXIBLE PAVEMENT DEFLECTION. Ramos, J.A., Castro, M. Construction and Building Materials 25 (8), 3530-3539. 2011.

Abstract

In this research, the effect produced by a temperature change on a flexible pavement deflection is analysed. Deflection tests were carried out on a road at different temperatures. The equipment used to measure pavement deflections was a curviameter. Based on the results of this experimental study, a methodology was established to define the experimental pavement temperature adjustment factors for deflection. In addition, the pavement structure studied was modelled, by means of a multilayer system, to calculate the deflections that would be produced below the load application point and, next, calculating the corresponding theoretical pavement temperature adjustment factors for deflection. Finally, the results obtained from the experimental study, theoretical analysis and main existing models are compared. The statistical analysis performed shows a good agreement between the experimental and theoretical obtained factors.

Highlights

► We study the influence of the asphalt mix temperatures on a flexible pavement.
► We obtain experimental adjustment factors by pavement temperature for deflection.
► We establish a methodology to calculate experimental factors, using curviameter.
► We define a new methodology to obtain theoretical adjustment factors.
► We perform a statistical analysis among obtained factors and main existing models.

Keywords: Deflection; Pavement temperature; Young modulus; Flexible pavement; Curviameter; Multilayer study

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OPERATING SPEED AND SPEED DIFFERENTIAL FOR HIGHWAY DESIGN CONSISTENCY

OPERATING SPEED AND SPEED DIFFERENTIAL FOR HIGHWAY DESIGN CONSISTENCY. Castro, M., Sánchez, J. F., Sánchez, J. A., Iglesias, L. Journal of Transportation Engineering, 137 (11), 837-840. 2011.

Abstract
A critical factor in highway design is maintaining a good consistency with a road geometry that fits the drivers’ expectations. Presently, highway geometric design consistency is usually evaluated on the basis of operating-speed profile analysis, which requires the use of operating-speed models. This paper presents research carried out in Colombia consisting of a study of vehicle speeds on tangents and curves of two-lane rural highways. Car speeds were measured on the approach tangent and at the beginning, middle, and end points of curves by using two radar meters. The operating-speed prediction models that were developed are described. The speed change experienced by drivers from tangent to curve was also studied, and a model is presented that predicts this change. Finally, the model developed for operating-speed prediction at the midpoint of curves was compared with equivalent models calibrated in other countries and applied to a Colombian highway. This comparative study highlights the importance of using speed-prediction models calibrated according to local conditions.

Keywords: Traffic speed; Highway and road design; Traffic safety; Models

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ALIGNMENT INDICES AS A TOOL TO EVALUATE SAFETY AND DESIGN CONSISTENCY IN TWO LANE RURAL ROADS

ALIGNMENT INDICES AS A TOOL TO EVALUATE SAFETY AND DESIGN CONSISTENCY IN TWO LANE RURAL ROADS. Castro, M., Sánchez, J. F., Pardillo-Mayora J. M. 3rd International Symposium on Highway Geometric Design. Chicago (U.S.A.). 2005.

Abstract

With the objective of assessing the relationship between alignment indices and accident records, and the applicability of these indices to roadway design consistency evaluation for two-lane rural highways, a research project has been conducted at Madrid Polytechnic University. Data from eight Spanish highways with diverse terrain conditions divided into sections of homogeneous characteristics, excluding intersections, were analyzed. Ten alignment indices were considered, and their relation with crash rates over a 5 year period was analyzed. Based on the results of the analysis, the most suitable indices to evaluate roadway design consistency were identified. Additionally, threshold values of the selected indices for consistency rating of roadway segments were established. This consistency rating method was applied to a sample set of Spanish highway segments. The results show good agreement with those obtained with the Interactive Highway Safety Design Model (IHSDM) Design Consistency Module.

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REVISING A GEODESY AND CARTOGRAPHY ENGINEERING CURRICULUM

REVISING A GEODESY AND CARTOGRAPHY ENGINEERING CURRICULUM. Castro, M., Iglesias, L., Rodríguez-Solano,  R., Sánchez J. A. International Journal of Engineering Education, 24 (6), 1180-1190. 2008.

Abstract
In the 1990s, a new degree, Geodesic and Cartographic Engineering, was created in Spain. It is a post-graduate degree, lasting two years. At present, Spanish university degrees are being redefined for their adaptation to the European Higher Education Area (EHEA). Thus, after more than ten years of experience and in view of the implementation of the EHEA, it is essential to analyse how well the degree curriculum is adapted to the professional requirements of our graduates in their working lives. A survey of former
students was taken to gather a profile of graduates, job positions and their opinions about the courses they studied. The relationship between the curriculum and the Master's theses written by the students was also examined.

Keywords: Engineering surveying; geodesy; cartography; photogrammetry; mapping; remote sensing; cadastre; curriculum

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STRUCTURAL DESIGN OF ASPHALT PAVEMENTS ON CONCRETE BRIDGES

STRUCTURAL DESIGN OF ASPHALT PAVEMENTS  ON CONCRETE BRIDGES. Castro, M. Canadian Journal of Civil Engineering, 31 (4), 695-702. 2004.

Abstract
Traditional methods for the structural design of pavement cannot be applied to the design of pavement on bridge decks. In this paper, a new method for the structural design of asphalt pavement on concrete bridge decks is presented. The method can be applied to pavement on girder, slab, and box-girder bridges and can be used whatever the considered degree of bonding between pavement and deck. The method consists of modelling the deck as a two-layer system and then calculating stresses and strains in the pavement–deck system by means of a multilayer system. The proposed methodology has been applied to study the behaviour of asphalt concretes, porous asphalts, and stone matrix asphalts on girder, slab, and box-girder bridges. There is a conclusion of this application that stands out for its practical character. The stone matrix asphalts have the best performance if fatigue is the main concern.
Key words: bridge decks, asphalt pavement, design.


Les méthodes traditionnelles de dimensionnement de revêtements ne peuvent être appliquées à la conception des revêtements bitumineux des tabliers de pont. Cet article présente une nouvelle méthode de dimensionnement de revêtements bitumineux des tabliers de pont en béton. Cette méthode peut s'appliquer aux revêtements des ponts à poutres, des ponts-dalles et des ponts à poutres en caisson. De plus, elle peut être utilisée peu importe le niveau d'adhérence considéré entre le revêtement et le tablier. La méthode consiste en une modélisation du tablier en tant que système bicouche, puis au calcul des tensions et des contraintes sur le système tablier-revêtement en utilisant un système multicouche. La méthodologie proposée a été appliquée à l'étude du comportement des bétons bitumineux, des enrobés drainants et des microbétons bitumineux sur les ponts à poutres, les ponts-dalles et les ponts à poutres en caisson. Une conclusion de cette étude se distingue par sa nature pratique : les revêtements microbétons bitumineux offrent le meilleur rendement si la fatigue constitue la préoccupation principale.
Mots clés : tabliers de pont, revêtements bitumineux, dimensionnement.


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FATIGUE AND HEALING OF ASPHALT MIXTURES: DISCRIMINATE ANALYSIS OF FATIGUE CURVES

FATIGUE AND HEALING OF ASPHALT MIXTURES: DISCRIMINATE ANALYSIS OF FATIGUE CURVES. Castro, M., Sánchez, J. A. Journal of Transportation Engineering, 132 (2), 168-174. 2006.

Abstract
Fatigue laws obtained by means of laboratory tests do not usually take into account the fact that asphalt mixtures in highways have rest periods (without loads). These rest periods tend to increase the fatigue life of mixtures due to the phenomenon known as healing. A new fatigue test which includes rest periods has been developed. In order to study healing, tests with and without rest have been carried out on asphalt concrete, and the corresponding fatigue curves have been obtained. The test results show an increase of five to ten times fatigue strength. This paper summarizes the main experiences. The testing method used in the research is described. The results are analyzed by means of a statistical technique called discriminate analysis.

Keywords
Asphalt pavements, Mixtures, Fatigue, Laboratory tests

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