Optimization of Orientation Vertical Signaling of the Portuguese Traffic
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Optimization of Orientation Vertical Signaling of the Portuguese Traffic Signaling Regulation Maria Rita Carneiro Pacheco Marques Guedes Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1, 1049-001 Lisboa Abstract: Road safety plays an extremely important role in the lives of both drivers and pedestrians that use the existing road network on a daily basis. By establishing road safety regulations and applying its resources, the practice of road safety, together with the conscious judgment of its users, allows the reduction and prevention of accidents. One of the available road safety resources is vertical signaling. Infraestruturas de Portugal (IP), which is responsible for 85% of the Portuguese road network, invests approximately 6 million euros per year in vertical signaling, 35% and 27% of which were allocated to orientation vertical signaling in 2011 and 2015, respectively. This study assessed if the cost of vertical signs (presented in €/m2) can be reduced through the optimization of their area, while maintaining their legibility and visibility. As such, it examined the total number of orientation vertical signs produced by IP in 2015 and, applying two calculation models, it forecasted the cost of their production and installation for a period of 15 years. Then, testing a different signaling font, and 4 different lettering applications from Spain, UK, USA and South Africa, the study verified that at least 3.75 million of euros could be saved in orientation vertical signs in Portugal if the lettering DIN 1451 Engschrift was applied. Key-Words: Road safety, vertical signaling, legibility, lettering, survival, optimization, cost signaling, which includes a variety of signs that 1 Introduction guide the drivers and the pedestrians along the According to Vehicle Portuguese Association road. In Portugal, the huge amount of (Associação Automóvel de Portugal, ACAP orientation vertical signs and their great size 2013), there are 5.83 millions of cars in explain the importance of attempting to reduce Portugal for 3.9 millions of families, which their size and, consequently, the cost of their corresponds to more than one car per family. production and installation (calculated in €/m2). Importantly, these vehicles are concentrated in This study tests the hypothesis that the the cities and their peripheries. Therefore, the application of a different lettering in Portuguese need of avoiding and reducing car accidents vertical signs can reduce their area and, through the application of road safety consequently, the cost associated with their measures such as road safety signs has production and installation, while maintaining significantly increased. their legibility and visibility, and as such safety There are different groups of road safety signs conditions. Firstly, the study reviews the with specific applications, but all of them aim to standards of different countries such as the send a clear message with useful meaning to United Kingdom, United States of America, its users. One of these groups is vertical South Africa and Spain. Their analysis and 1 comparison with the case of Portugal allows The choice of lettering size depends on several the evaluation of convergence and divergence factors, such as speed, number of messages points. Secondly, it calculates the total number on the sign, number of road lanes and of signs produced and installed in 2015 in positioning of signs (ground mounted or Portugal and forecasts this number for a period overhead signs). of 15 years. Thirdly, it calculates the costs The Portuguese standard complies with the UK associated with their production if different standard, which involves the application of letterings are applied, according to 5 different formulae to calculate the parameter “x-height”, standards used in other countries. proportionate to the height of the lower case of “x” (Table 1, source: RST). 2 Literature review Table 1 – Height of upper case letters (mm) (Source: 2.1 Portuguese Standard RST) According the Portuguese standard of signaling regulation (Regulamento de Speed (km/h) Ground Ground Ground mounted mounted Overhead Sinalização de Trânsito, RST) (RST 1998), Overhead 40-60 20 14 28,5 20 vertical signs should be positioned where 60-90 28,5 25 30 28,5 90-110 35 30 43 35 roads can lead to danger or doubts to its users 110-130 43 40 50 43 and where they can provide useful information 4 words 5 or more words This lettering size is very important in ensuring to drivers and pedestrians. that users are able to read the message Furthermore, their presentation is very provided by the sign, in order to make timely important for their recognition – color, shape decisions while driving. and size being three main aspects to be considered. Orientation signs are mostly 2.2 Spanish Standard rectangular (although direction signs are arrow As stated in the Spanish standard, known as shaped) and made of a material with “Norma 8.1-I.C”, vertical signaling has three retroreflective properties. Moreover, depending main goals: to increase safety, efficiency and on the road where they are positioned, they comfort. Thus, there are two types of vertical can be blue (freeways), green (at principal signaling presented in this standard - signs itineraries “itinerários principais) or white (at with fixed content and variable content – the conventional roads and complementary last ones being known as “carteles”, in itineraries “itinerários complementares”). Spanish, or orientation vertical signs (M. As reported by IMT (Instituto de Mobilidade e Fomento 2014). Transportes), the lettering used in Portugal is Most of these signs are rectangular (except for the Transport Alphabet (Transport Medium and the direction signs, which follow the rules Transport Heavy) and it is composed by letters stated in the Portuguese standard (Section and numbers. To form a word, in order to help 2.1) and their color depends on the road where the driver to read the message showed on the they are positioned. sign clearly, the first letter is capitalized This standard presents three different roads: (Roque, n.d.) “autopistas” (two carriageways with no access 2 to neighboring properties) and “autovías” (two The orientation vertical signaling presented in carriageways with limited access to this standard is composed by green neighboring properties), where the sign background and white messages, mostly in a background is blue and the legend is white and rectangular shape (MUTCD, FHWA 2009). “carreteras convencionales” (one carriageway MUTCD distinguishes three different kinds of with no limited access), where the background roads: freeway (two carriage way with tolls), sign is white and the legend is black. expressway (two carriage way where toll The lettering used in Spain is the CRIGE payments can be implied) and conventional Alphabet, which letters and numbers road (one carriage way). dimensions are currently under approval. Table The lettering used in the USA is the FHWA 2 shows the height of upper case letter (Hb) for Alphabet, also known as Highway Gothic, and each road presented before (height of lower is presented in six different ways (series B to case letter is equivalent to 3/4 of upper case F), series E modified being applied in letter). orientation vertical signaling. The minimum Table 2 - Height of upper case letters (Source: Norma height for upper case letters is shown in Table 8.1-I.C) 3 (the height of lower case letter is 3/4 of upper Sign Hb (mm) case letter): Cartel de dirección propia (Selection of 400 roadways) Table 3 - Minimum height for upper case letters (mm) Overhead Cartel de salida (Source: MUTCD) (Selection of 400 Minimum height for upper case roadways) Road letter (mm) Banderolas 400 Conventional Preavisos (Pre- 150 (200) 360 Road Signaling) Expressway 270 (340) Confirmaciones 270 Freeway 400 (Confirmation) Flecha dirección 360 (Direction) Localización 2.4 UK Standard (Identification of 200 Groundmounted localities) Preavisos – glorieta As stated in the UK standard, known as “Traffic 200 (Pre-Signaling) Flecha dirección - Signs Manual”, vertical signs must control and dimensión reducida 150 guide road traffic to promote road safety. (Direction) Preavisos - dimensión 150 Moreover, signs must deliver their message reducida (Direction) clearly and at the correct time, enabling drivers to correctly decide which way to go. 2.3 USA Standard In the UK standard, orientation vertical signs According to the USA standard, known as are presented as directional signs (rectangular “Manual on Traffic Uniform Control Devices for shape except for arrow signs) with blue Street and Highways” (MUTCD), the main goal background when used on motorways, green of vertical signaling is to provide regulations, background on primary routes and white warnings and guidance information for road background on other roads (Department for users. In order to convey the messages to the Transport, Traffic Signs Manual 1982). drivers, words, symbols and arrows are used. 3 The lettering used in the United Kingdom is the information by consistent positioning of this Transport Alphabet (Transport Medium and information, d) simplify a driver’s reading Transport Heavy) as in Portugal, and the main process by limiting legend display to the design characteristics are the same as minimum (SADC, Road Traffic Signs Manual presented before. The calculated “x-height” 2012). corresponds to what’s presented in Table 4 There are different types of orientation signs: (height of upper case letter is equivalent to 7/5 location, local