DESIGN OF SUSTAINABLE URBAN TRANSPORT …...and transportation sectors. SUMP moves the focus from...

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International Journal of Civil Engineering and Technology (IJCIET)

Volume 9, Issue 10, October 2018, pp. 2131–2147, Article ID: IJCIET_09_10_210

Available online at http://www.iaeme.com/ijciet/issues.asp?JType=IJCIET&VType=9&IType=10

ISSN Print: 0976-6308 and ISSN Online: 0976-6316

©IAEME Publication Scopus Indexed

DESIGN OF SUSTAINABLE URBAN

TRANSPORT INFRASTRUCTURES: A REAL

CASE APPLICATION IN ITALY

Armando Cartenì

Department of Engineering, University of Campania “Luigi Vanvitelli”,

via Roma 29, 81031 Aversa (Caserta), Italy

Maria Luisa De Guglielmo

Department of Civil Engineering, University of Salerno,

via Giovanni Paolo II, 84084 Fisciano (Salerno), Italy

Ilaria Henke*

Department of Civil, Architectural and Environmental Engineering,

University of Naples, Federico II, via Claudio 21, 80100, (Napoli), Italy

*Correspondence Author Email: [email protected]

ABSTRACT

The new look of urban transportation planning has the main aim to propose

sustainable solutions. This aim is particulate suitable for the high congested areas.

Within this goal, the East area of the city of Naples, in South of Italy, with over 11

inhabitants per km2 and daily road congestion problems was a useful case study to test

transport sustainable solutions.

Starting from the congested current condition, according to the actual circulating

solution (e.g. traffic-lighted intersections), the level of service was investigated. The

results showed the congestion level up to 90% in the peak hours. On this basis, it was

decided to design a complex design scenario to reduce traffic congestion in the area.

At large roundabout, new path, rational bus stops and all the necessary pedestrian

crossings infrastructures were designed according to rational criteria. A wide survey

campaign and traffic counts were also performed in order to better estimate both

current and future traffic flows through macroscopic simulation models.

The results of the simulation show that the solution identified will solve both the

current traffic congestions and will allow to ensure acceptable levels of service also in

a future scenario when the planned new activities in the area will be completed.

Key words: Sustainable mobility; transportation planning; transport infrastructures;

public transport; passenger satisfaction; demand estimation; traffic congestion;

transportation network.

Design of Sustainable Urban Transport Infrastructures: A Real Case Application in Italy


Cite this Article: Armando Cartenì, Maria Luisa De Guglielmo, Ilaria Henke, Design

of Sustainable Urban Transport Infrastructures: A Real Case Application in Italy,

International Journal of Civil Engineering and Technology (IJCIET) 9(10), 2018, pp.

2131–2147.

http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=9&IType=10

1. INTRODUCTION

Since 2014, a new look appears to be in the field of urban transport planning in European

countries. In fact, for a long time the urban areas showed the need to have more planning and

management tools to achieve a more sustainable, accessible, efficient and competitive urban

mobility. In 2014, the European Commission has published specific guidelines [1]with the

specific aim to involve citizens, stakeholders and decision makers in the coordination among

different urban policies (transport, land use, environment, economic, social and energy) in a

more comprehensive transportation planning. In contrast with the traditional transportation

planning procedures, characterized by some limitation related to the policy areas involved in

the plan (e.g. parking, roads, public transport services), the new Sustainable Urban Mobility

Plan (SUMP) proposed by European Commission represents a more comprehensive plan

integrating all the urban actors involved (e.g. citizens, decision-makers as local and national

authorities, stakeholders, professionals and transport users). So, a multidisciplinary approach

must be integrated in its development covering environmental, urbanized, economic social

and transportation sectors. SUMP moves the focus from traffic to people with significant

advancements in the direction of a sustainable mobility (e.g. explained [2]) jointly with the

quality of life, overcoming a too sectorial vision of transport without interactions between

interventions and sectors. Since very few years, different European cities are developing their

SUMPs (or part of them) and also in Italy even if only recently (October 2017) an Italian

specific guideline was approved [3]. In 2016, the city of Naples, in South of Italy, has already

formalized the first acts of its SUMP. For developing these acts, in compliance with the

European guidelines, the city of Naples has proposed an application of the urban scale of a

theoretical planning decision-making process, proposed in [4]. This innovative

methodological approach introduces a complex planning process based on “three legs”

corresponding to the three main actors involved (technical planners, decision-makers and

stakeholders) in three parallel and intertwined processes: i) the use of quantitative methods for

all the technical activities (e.g. impacts estimation; cost-benefit analysis to compare multiple

design scenarios; ii) a bounded rational decision-making process; iii) the stakeholder

engagement process. The bounded rational model assumes that the actors are still goal-

oriented, but they implicitly consider their cognitive limitations in attempting to achieve those

aims. Furthermore, since different decision-makers are involved in a transportation planning

process, it is very likely that their aims are diverse and possibly contrasting, not to mention

those of the variety of stakeholders involved in the process. This new planning process aims

to find a satisfactory compromise rather than the optimal solution. Following this

methodological approach (more details inside [5], the process followed in Naples SUMP was

rational, adaptive and participated and inherently dynamic with objectives that can be

reformulated until achieving a really sustainable mobility system. The SUMP’s vision for

such a complex city (taking always into account the dynamic evolution of its definition) has

as core a shared mobility system, including traditional urban public transport systems and

bike, car and taxi sharing services. Another specific characteristic of Naples SUMP is to

enlarge transport quality. While in public transport it has long been understood that this

should be designed and managed by increasing the perceived quality of the users

([6][7],[8][9]), the choices for private transport seem, up to now, to have been linked just to

specific objectives. In fact, private transport has always been a disincentive mode of transport.

Armando Cartenì, Maria Luisa De Guglielmo, Ilaria Henke


Because of the use of private vehicles can be discouraged but not be cancelled, because it

remains in the freedom of every citizen, the idea proposed in this study (and carried out in the

PUMS) is that quality objectives must be pursued for the entire transport system of a city to

increase the overall welfare of its citizens.

If, as mentioned, the aim of the new vision of urban transport planning is to propose

sustainable solutions in very congested areas, then the case study appears to be particularly

interesting. The east area of Naples has 1 million inhabitants, with a density of 11.27

inhabitants per km2 and daily road congestion problems. This area is ready for a deep

transformation: the great abandoned industrial area will be a residential area, with services,

green areas, etc. Urban studies (which are not in the aim of the present paper) have quantified

that once the project is completed, the mobility demand affecting this area will increase by

20-40%: this relevant percentage has found just road infrastructures already congested.

Starting from the previous synthetic considerations, rational and sustainable solutions have

been proposed to improve the current congestion problems, but also capable of absorbing the

expected traffic flows in the urban planning scenario. The results of this study were also

considered in the Naples PUMS ([10]).

The paper is organized as follows. In the next section, the main elements of the

methodological approach are summarized; afterwards the case study, the mobility surveys, the

demand analysis and the simulated scenarios are described and discussed. Then the results are

given and, finally, the main conclusions are reported.

2. THE DESIGN METHODOLOGY

The methodology applied in this study is largely consolidated in the scientific and

professional literature. It consists in the implementation of several estimation phases and in

the evaluation of different design solutions through the application of specific mathematical

models (see also Fig.1 for correlation among phases):

Analysis of the study area and context: planning documents and tools of Naples (Italy),

available data etc.;

Mobility surveys and traffic counts: preparatory information to estimate the critical issues of

the area;

Design scenarios identification: analysis and definition of alternatives;

Macroscopic simulation model: application to the study area;

Impacts estimation: demand level and level of service attributes (e.g. travel times and costs);

Choice of the final design solution: cost- benefit analysis (see for details [11][12]).

Figure 1 The proposed design methodology



The estimation of traffic flows, both in the base situation or reference scenario and in

design ones were performed through an ad hoc macroscopic simulation model implemented.

This model has allowed to estimate (and verify) the effects of the different infrastructural

design solutions (e.g. geometry, regulations, paths) in term of paths followed, travel times,

congestion level in different time periods. It has also allowed estimating all the synthetic

indicators useful to evaluate the proposed design scenario and eventually integrate and/or

modify them.

The basic idea to overcome the main transport problems of the study area was to develop

a satisfactory design solution following the paradigm of a "4 S infrastructure". This type of

proposed infrastructure has to be (as illustrated in Fig.2) a global expression of road and

transport engineering skills in the light of the new criteria of environmental sustainability and

technological modernity of infrastructures.

Figure 2 The idea of the "4 S” designed infrastructure

Sensitive infrastructure. An infrastructure sensitive to the context is pleasant to the eye and

well-integrated with the development necessary for revitalizing the east area of the city. Great

effort is given to achieve a new and specific identity to an urban area that appears, in the last

decades, too abandoned.

Sustainable infrastructure. An infrastructure can become sustainable if attention to the

environment, liability and accessibility are given in the development of design solutions. The

proposed project, in fact, is based on i) the recovery of existing materials (e.g. the stone

material of volcanic origin: cobblestones and paving stones, the so called “sampietrini” and

“basoli”); ii) the use of pavements aimed at reducing polluting substances (e.g. photo-catalytic

materials); iii) the road network to minimize the possible phenomena of congestion and points

of conflict. In addition, a specific cycling route has been included in the future scenario,

aimed at connecting the directional centre of Naples with the future green areas envisaged in

the project area.

Safe infrastructure. A safe infrastructure is safe for all types of road users: private cars and

public vehicles, pedestrians and cyclists. For achieving this complex purpose, the designers

have paid attention to the proposed design solutions through the creation of "protected" cycle

and pedestrian routes, comfortable road geometries for vehicles (i.e., designing the shape of

road edge for accompanying the maneuvres and avoiding conflicts).

4 S Infrastructures

Sensitive

Sustainable

Safe

Smart



Smart infrastructure. A smart infrastructure is technologically advanced through the use of

appropriate technologies aimed at reducing energy consumption (e.g. led lamps for street

lighting, also in underpasses) and safety (e.g. surveillance systems, especially in the numerous

existing underpasses).

3. THE APPLICATION CASE STUDY: EAST AREA OF NAPLES

METROPOLITAN AREA (ITALY)

3.1. The current level of congestion of the transport network

The starting point for the choice of the design solution to be proposed was the analysis of the

current transport critical issues of the investigated area.

Poor legibility of the road network. The road network serving the east area of the city is

strongly conditioned by the presence of the connections with the urban motorway, the Rome-

Naples motorway, the Naples - Pompeii – Salerno motorway and with a rural road, the S.S.

162, connecting Naples with the surrounding cities of the Vesuvius area. Furthermore, the

wider part of these connections between urban roads of east area and the above-mentioned

motorways are developed in viaduct with a strong environmental impact on the liveability of

the area. Another impact feature is the presence of the terminal sections of the Rome - Naples

railway line and the Circumvesuviana railway lines. These last mainly develop by causeways

and constitute strong elements of interruption of continuity of the urban road network.

Moreover, the road network of this area is characterized by the absence of easily recognizable

territorial reference points: in other words, this area could appear anonymous and poor

attractive for a new driver.

High frequency of traffic accidents. The studied area is heavily affected by the phenomenon

of road accidents and operating speed that overcome the imposed limit (see next sections for

more details).

Low safety of people. From inspections made by technicians has emerged that the studied

roads (in particular, parts of those roads that have underpasses: two on via Galileo Ferrari and

one via Gianturco) do not have satisfactory characteristics of intrinsic safety.

Absence of technological systems for infrastructures. The roads subject to intervention are

located near the directional centre, and therefore, in an area with a high concentration of

services and offices of regional and national relevance (Court of Naples, Campania Region,

Parthenope University, etc.). It has to be said that, in recent years, this area has already had

first important transformations: e.g. in a road, called via Brin, several advanced tertiary

companies have opened their offices. Furthermore, in the coming years, will be important

developments for the expansion of the directional centre and the realization of the

implementation, urban plans in the areas of two abandoned great industrial plants. Despite

this, it also has to be said that there is still a total absence of technologies (e.g., widespread Wi

- Fi connections, advanced public lighting systems, monitoring systems, etc.).

3.2. The main investments expected in the studied area for 2020

The reference period was assumed for the year 2020 because of, for that year, is possible that

all the main investments for the requalification of the East area of Naples will be realized. In

addition, demographic and socio-economic trends were also explicitly considered in the study.

In the following, the main planned interventions are summarized, according to the current

urban planning plans, that will have a significant impact on the local mobility (e.g. traffic

congestion):



New laboratories, libraries, University Departments, public park and a conference center are

planned in the ex Cirio industry in San Giovanni a Teduccio area, for an overall of about

200,000 m3 of buildings and for 28,000 m

2 of parking.

A new tramway within the coastal redevelopment program.

An area of 11,385 m2, located in the district of S. Giovanni will involve the construction of a

residential settlement with parking and a public green area.

A new hospital (500 beds, 80,000 m2) in the district of Ponticelli will be realized with an aim

to bring together three old hospitals, currently located in the historical centre of the city.

Near the Madonnelle station of the Metro Line 3 a proposal provides for the construction of a

residential complex with a public park.

The proposal concerns an area (10,494 m2) located in the district of Ponticelli and includes the

construction of buildings (12,710 m3), public district equipment (green area and sports), and a

public road.

The area subject to intervention (226,242 m2) is located on abandoned refinery and includes

the disused industrial settlement of the Icmi industry. Construction of an urban park with

sports facilities and services are designed. Furthermore, the construction of another 3 roads

and the extension and upgrading of an existing one are provided.

Recovery of an old industrial building (more than 50,000 m3) to be used for the production of

goods and services.

The current urbanistic plan provides the removal of the old industrial buildings and, in their

place, the realization of an integrated productive pole with several types of activities (also

commercial for the large distribution), primary public urbanizations (roads and parking) and

secondary public urbanizations (a district park area).

The project area (84,000 m2), located in the district of Ponticelli, involves the construction of

facilities for music.

The proposal provides for the redevelopment of a disused production area, ex Feltrinelli

industry, through the construction of public, commercial and residential equipment.

The project involves the redevelopment of an old industrial establishment, the Manifattura

Tabacchi. For this, wide area a new mixed-use, productive and residential is planned.

Urbanization works are the most important issue of this very large project that provides for

roads and public spaces, green area, buildings, parking.

Completion of the Naples executive centre.

The proposal provides for the demolition of industrial buildings (inactive and in a condition of

serious degradation) present in Via Vesuvio.

In via Argine, the construction of a residential settlement with a public parking is planned.

Redevelopment of an area located in via Argine, through the construction of residential

buildings, public facilities, and commercial activities.

Urban restructuring, by the demolition of existing buildings and by the following construction

of a residential building, a hotel and a commercial structure, in addition to the related primary

and secondary urbanization work consisting of new public roads, a public parking and public

green areas.

The project concerns an area of about 5,236 m2, in via Censi dell'Arco, and provides for the

construction of a residential building and parking.



In via Matteotti, a reconversion and requalification of private roads to public roads is planned

with the construction of green facilities, parking, new residential buildings and commercial

activities.

A public area is planned with green facilities along via delle Puglie, primary urbanization

work.

The project involves the construction of the new marina, shipbuilding, shops related to

boating, restaurants, fitness center, and service accommodation in the locality of Vigliena in

San Giovanni a Teduccio.

3.3. The expected socio-economic trends for 2020

The estimate of the population of the Campania Region was obtained with the standard

forecasting method of linear regression, using the data series recorded from 1991 to 2010, on

a municipal basis. The relationship between population trends and time was assumed to be

linear, i.e. the growth curve is represented by a straight line (see Fig.3). The estimated

population P at time t was determined using the simple interest formula, where the arithmetic

rate of increase is considered constant. Called P0 the population at the initial time t0 and i the

arithmetic rate of increase in the unit of time, the population estimated after t unit of time will

simply be given by: P=P0(1+ti). The calculation of the angular coefficient of the linear

interpolation line was carried out with the "least squares method", i.e. through the

minimization of the sum of squares of the vertical deviations between the observed and

calculated values. The results obtained were verified with the provincial demographic

forecasts for the year 2020 on a provincial basis obtained with the use of the model for

components (Cohort Component Model). Regarding the demographic evolution in 2020, it is

estimated that the total population of the Campania region is equal to 5,884,132, with an

overall increase of + 1.02%. An increase of + 4.3% is estimated in the province of Caserta and

+ 1.63% in the province of Salerno. The province of Naples remains stable with an increase of

+ 0.19%, while in the provinces of Benevento and Avellino the population decreases

respectively by -0.76% and -0.28%. In summary, we estimate a slowdown in the overall

growth trend recorded in the decade 2001-2010 and a trend reversal for the provinces of

Avellino and Benevento.

Figure 3 Projection of the total population in the Provinces of Napoli to year 2020



4. SIMULATION MODEL ESTIMATION

Over 285 traffic areas were identified: 266 within the city of Naples and 19 homogeneous

traffic areas outside. For the city of Naples, it was decided to carry out such a thick zoning

(illustrated in the following figure 4) in order to obtain a more precise modelling given that

the high concentration of both the resident population and employees as well as the plurality

of transport services offered (private and public).

Figure 4 City of Naples. (a) Road network [25]; (b) Corresponding zoning designed for the present study.

The macroscopic simulation model applied was composed by a within-day static models

with variable demand (for details see also [13][14][15]) which explicitly takes into account

accessibility variables ([16][17]) and consists of a supply model with urban cost functions (for

details see [18]) where the link impedance generalized cost was equal to: i) the sum of the

travel time (in a congested network for the car mode) plus the fuel monetary cost for the car

mode; ii) the sum of a travel time plus the ticket price for the public transport mode.

Furthermore, a standard multimodal Logit demand model with both level of services and

socio-economic attributes (for details see [19][20][21][22][23]) and an elastic Stochastic User

Equilibrium (SUE) assignment model for congested network (for details see [24]) were

applied.

Figure 5 The sub-activity of the macroscopic simulation model

5. MOBILITY SURVEYS AND TRAFFIC COUNTS

The East area of the city of Naples, widely described in this paper both at the current situation

and also in terms of planned interventions, presents a particularly complex point at the

intersection between two roads: via Emanuele Gianturco and via Galileo Ferraris. The main

characteristics of these roads are the following:



Via Emanuele Gianturco has, for the main part of its length two lane (3.50 m and 3.00 m in

width) for direction; shoulders of 0.50m; parallel parking; stops for public transport; sidewalks

of variable width (but often greater than 1.5 m).

Via Galileo Ferraris has sections with 1 and also with 2 lanes per direction. Generally, the lane

width is 3.00 m or 3.50 m; shoulders of 0.50m; parallel parking; stops for public transport;

sidewalks of variable width (but often greater than 1.5 m).

The intersection between the indicated roads is regulated by traffic lights.

Since the relevance of the indicated two long roads in the whole East area, in this section

the results of an important campaign of traffic and safety analyses are presented with the aim

to deeply understand the current situation and to propose a new sustainable configuration.

5.1. Traffic Counts

During the design of the final project, a wide survey campaign was carried in order to: i)

understand the main characteristics of the current road system in the project area and ii)

correctly apply demand models for estimating the traffic flows in the reference scenario. The

daily and hourly traffic flows and the current degree of congestion were estimated.

The analyst infrastructures, on the average working day (see Fig.6), resulted to be

travelled by about 28,000 passenger car equivalent (PCE)/ day. In terms of peak hour, the

analysis showed a uniform value of demand along the day, except for the early afternoon. A

maximum load is possible to attribute from 8.30 a.m. to 9.00 a.m. with over 4000 PCE/ hour.

The current level of service showed that, in the morning peak hour of a working day (see

Fig.7), the average degree of congestion (ratio between vehicle flow and capacity of the

infrastructure) results over 50% (78% as maxim peak) for several existing roads (in particular

for those roads confluent in the intersection between via G. Ferrari and via E. Gianturco).

The Average Daily Traffic (AADT) is about 17,000 vehicles/ day for the two directions of

via Ferraris, while it is over 15,500 vehicles/ day on both directions of via Gianturco.

Furthermore, on these roads, a percentage of about 78% -80% result to be cars, about 19% -

20% motorcycles and the remaining, about 2%, heavy vehicles.

Figure 6 Traffic counts in an average working day (current scenario)



Figure 7 Traffic counts in morning peak hour of an average working day (current scenario)

5.2. Speed Surveys

In order to quantify the current level of safety of the studied roads, a speed measurement

campaign on via Galileo Ferraris and via Emanuele Gianturco was carried out. In particular,

the speed measurements concerned via Galileo Ferraris, both in East and in West side, and via

Emanuele Gianturco, both in North and in South side. The measurements were made with

non-invasive tools: cameras with data processing software.

The surveys for the detection of average speeds were carried out in October 2013, during

non-peak hours of several average working days and during. In addition, more than 100

random measurements for each of the 4 monitored road were made.

In the following Figures 8 and 9, charts of observed frequencies of the measured speed

with a summary statistic are reported.

Figure 8 Observed frequencies of speed with summary statistic for both sides of via Emanuele Gianturco

The figure 8 shows that for the South side of via Emanuele Gianturco, the 40% of the

speed values are about 60 km/h and the 90% of observations are above 50 km/h. The North

side of this road is characterized by speed values over the imposed speed limit (30 km/h) and

just a percentage of 5% of the observations are within the limit. The 75% of recorded values

is over 50 km/ h. Furthermore, the average value (see fig.8) of all observations are 58.2 km/h

in the North direction and 51.3km/h in the opposite one.

0%

5%

10%

15%

20%

25%

30%

35%

40%

45%

30 35 40 45 50 55 60 65 70 75

freq

uenc

y

Observed speed [km/h]

via Emanuele Gianturco, South side via Emanuele Gianturco, North side

via Emanuele Gianturco Average speed Standard deviation Mimum Maximum

South side 58.2 km/h 7.3 km/h 35.2 km/h 75.8 km/h

North side 51.3 km/h 11.5 km/h 29.7 km/h 75.4 km/h



Figure 9 Observed frequencies of speed with summary statistic for both sides of via Galileo Ferraris

The two directions of via Galileo Ferraris, as the figure 9 shows, are characterized by

lower values of speed those of via Emanuele Gianturco. This circumstance is probably due to

the bad surface condition of road pavement. The East side of the road 45 km/h is the speed of

about 25% of vehicles, on the contrary 50 km/h is the speed of about 30%. As the figure 9

shows, the average values are 45.1 km/ h for the East side and 51.4 km/h for the West side of

via Galileo Ferraris.

5.3. Accident Data

The city of Naples recorded the accident data for Municipalities: the roads of reference area in

this study belong to the Municipality number 4. In 2011, 753 accidents with 3 fatalities and

451 injuries occurred. Furthermore, these values represented the 16% of total accidents in the

city, a little less of 10% of all fatalities and the 14% of all injuries. The city of Naples, in a

more recent statistic for the year 2016, reports 494 accidents with 2 fatalities and 303 injuries

occurred. Despite of an important decrease of accident by 35%, in 5 years, greater relevance

of these accident data is probably due to the presence of connections, of the studied roads,

with the motorway network: this characteristic might influence (as above described in speed

measurements) the operating speed of drivers and their poor attention to the urban

environment.

6. IMPACTS ESTIMATION

The wide study, above illustrated, about the current situation of the reference area has allowed

to estimate the demand flows both in the current situation and in 2020.

Figure 10 Simulated flows in morning peak hour of an average working day (current scenario)

0%

5%

10%

15%

20%

25%

30%

35%

25 30 35 40 45 50 55 60 65

freq

uenc

y

Observed speed [km/h]

via Galileo Ferraris, Est side via Galileo Ferraris, West side

via Galileo Ferraris Average speed Standard deviation Mimum Maximum

Est side 45.1 km/h 9.2 km/h 25.2 km/h 61.2 km/h

West side 51.4 km/h 10.7 km/h 25.5 km/h 66.3 km/h



In the reference scenario (2020) it can be estimated that, in an average working day, a

number of 40,000 passenger car equivalent (PCE)/ day will travel along these roads, with an

increase of about 44%. In the morning peak hour (see Fig. 10), a number of 5000 PCE/day

(corresponding to about +25%) will increase the current flow. Comparing these different

percentages of increases, it can be noted that great relevance has the type of planned activities,

that will be realized in the East area. In fact, the commercial activities are more attractive to

customers in the late afternoon.

A control of the levels of service for the roads was then made. In the morning peak hour

of a working day, the degree of average congestion (ratio between vehicle flow and

infrastructure capacity) results greater than 50% with peaks of 78% for many infrastructures

of the reference area, especially for those confluents at the studied intersection.

Starting from the existing circulation scheme, i.e. traffic-lighted intersection, by means of

a preliminary optimization of phases and time of green and red, the circulation conditions of

the project scenario were estimated (see Fig. 11). The level of service resulted unsatisfactory

with congestion indices of 90- 100% and more. In the light of this poor result was considered

to change the type of intersection: a roundabout (see Fig.12). With this design solution, a

more satisfactory level of service is expected thanks to a degree of average congestion

between fluid and satisfactory condition.

Figure 11 Simulated flows in a morning peak hour of an average working day. Reference scenario at

2020 with traffic light at via E. Gianturco –via G.Ferraris intersection.

Figure 12 Simulated flow in a morning peak hour of an average working day. Reference scenario in

2020 with roundabout at via E. Gianturco –via G.Ferrais intersection.

Finally, from the results of road accidents and speed measures, in order to ensure an

adequate level of safety for both vehicles and pedestrians, all the appropriate horizontal and



vertical signs have been provided for. Vehicle and pedestrian routes have been rationalized

and highlighted (e.g. maintaining the colour of the cycle lanes along its entire path); measures

have been taken against architectural barriers; high standards of brightness and visibility have

been especially guaranteed for pedestrian crossings; the vehicular flows at the intersection

were channelled through special divisional islands in order to avoid hazardous maneuvres.

7. DESIGN SCENARIOS IDENTIFICATION: THE NEW

ROUNDABOUT

The intersection between the two roads is configured as a large elongated triangular area of

about 3250 m2. The great extent of this area, now rather abandoned, has required a complex

planning in order to into account all necessities:

a clear route for vehicles, without the possibility of unregulated maneuvers: that means

obligatory directions, easy to maneuver of heavy vehicles and buses, absence of unregulated

parking; widespread and clearly legible signs;

a safe and comfortable path for many pedestrians who will be attracted by new commercial

settlements and the new green areas: that means wide sidewalks (larger than 1.5m), pedestrian

crossings, bus stops and also all types of necessary urban furniture;

a rational, comfortable a safe path for cyclists: that means taking into account the cycle lanes

along the roads, in correspondence of pedestrian crossings and bus stops with aim to avoid the

more common points of conflict and, finally, give to the cyclists the possibility to cross the

intersection even if there is a large roundabout.

For all the mentioned reasons, a complex design solution based on two counter-clockwise

circulation devices has been identified as the more appropriate in a wide range of solutions: an

ovoid central island, elongated in the longest verse of the triangular area, and a side triangular

area as the Figure 13 shows. It has been said that this last lateral triangular area has the

presence of a fuel distributor still in activities that will be moved as soon as possible.

Figure 13 The design roundabout at via E. Gianturco –via G.Ferrais intersection. A preliminary

geometric design of the whole area of intersection: roundabout, cycle path, bus stops and the

pedestrian crossings.

According to the Italian decree [26], there is now a standard for the existing intersection,

which have to adapt: the regulation is for new construction of an intersection. Taking into

account both the indicated decree (for the dimension of elements) and the necessity of the

wide area in adaptation, the design of this intersection is considered an ovoid island



characterized by maximum orthogonal dimensions of 36 m and 25 m with a surmountable

part from vehicles; a circular ring of 8 m; shoulders of 0.50 m from both sides; cross slope of

2% to facilitate the movement of water from the traveled lanes towards both shoulders. The

entrances and exits of the roads arriving in a roundabout are sized and located so as to

guarantee a correct deviation of vehicular trajectories. In fact, a roundabout in urban

environment also has the task of creating safe maneuvers and moderating speeds according to

the well-known criteria of traffic calming.

Details about geometric and functional choices for the cycle path, the bus stops, the

pedestrian crossings and the main street furniture details are not given to save space.

In order to estimate capacity and level of service of each road which enters in the

roundabout as a function of the waiting time, the SETRA methodology [27] was used. Taking

into account the relevant geometric parameters, the incoming and outgoing traffic volumes,

the traffic volumes circulating near the entrances and of the simple capacity, it was possible to

estimate the percentage of the capacity reserve with aim to have a judgment on the quality of

circulation. The operating conditions of this new roundabout resulted to be characterized by

values of reserve capacity in the range of 15-30%, that means a satisfactory level of service

and also greater than 30%, that means fluid circulation. The following tables 1 summarizes

the results, without more details for saving space.

Table 1 Level of service for the roads that arrive in the new roundabout.

via Galileo

Ferraris,

West Side

via Galileo

Ferraris,

Est Side

via Emanuele

Gianturco,

South side

via Emanuele

Gianturco,

North side

operating conditions at 2020 fluid fluid fluid fluid

operating conditions before

2020 satisfactory satisfactory fluid satisfactory

As the reader can see in table 1, the level of service was carried out in the operating

conditions of the indicated roundabout, both in the reference year (2020, with all the new

activities, settlements, infrastructures, public transports etc.) and also at a shorter time (just

after the constructions of the roundabout, without the all the new attractors).

The previous classical approach to evaluate the level of service, under the hypothesis of a

statistic equilibrium, takes into account stationary models of flows. Under this condition, the

risk for the designer is well known: an oversized of geometrical elements of the intersection

(unlike with models that consider the transient regimes, see for example [28]). In this respect,

a deeper analysis could be done in the next step of the design taking into account, however,

that in this wide area the availability of space is not a problem.

8. CONCLUSIONS

The new vision of urban transport planning has the specific aim to propose sustainable

solutions in a very congested area. The East area of the city of Naples, in South of Italy, has

11.27 inhabitants per km2 and daily road congestion problems. This area is characterized by

relevant abandoned industrial settlements and is going toward a deep transformation: new

infrastructures, new public transport, new residential areas, with all types of services, and

green areas are in planning.

In the present study, rational and sustainable solutions have been proposed to improve the

current congestion problems, but also capable of absorbing the expected traffic flows in the

urban planning scenario. The results of this study were also considered in the Naples PUMS

([10]).



The present study was addressed: i) to estimate mobility demand expected at 2020

(reference year for the renewal of the East area) and, on this estimate, ii) to propose

sustainable projects able to guarantee adequate levels of comfort and safety for private and

public vehicles, pedestrians and cyclists. In particular, in this paper a specific relevance is

given to a significant intersection.

After a deep analysis of the main investments, and their characteristics, a safety analysis

was carried out. A wide survey campaign and traffic counts were also made in order to

consider two scenarios: a current scenario and a reference scenario in 2020.

The flows, by using simulation models since 2020, resulted influenced by several factors:

a progressive migration of the population of the city of Naples towards the outermost areas;

the end of construction of the Metro Line 1 and other planned interventions for public

transport;

the renewal of the East area of Naples with the construction of a number of infrastructures and

constructions.

As it is easy to understand, a part of the previous factors will tend to decrease the use of

private vehicles while the other part will tend to generate a new demand for mobility from and

toward the renewal areas.

Overall, it is estimated that, on an average working day, the planned infrastructures will be

travelled by about 40,0000 passenger equivalent cars (PCE)/ day, about 44% more than those

passing today. On the other hand, at the morning peak hour, more than 5000 (PCE)/ day are

expected (that means 25% more than the current ones). These different percentages are due to

a new mobility demand closely connected to the types of activities that will be realized.

The level of service for the current situation shows how, in the morning peak hour of a

working day, the degree of average congestion (ratio between vehicle flow and capacity of the

infrastructure) results over 50% with peaks of 78% for several infrastructures of the reference

area, especially for those confluents in the intersection between via Galileo Ferrari and via

Emanuele Gianturco.

Starting from the congested current condition and maintaining the pre-existing circulation

solution for the indicated intersection (traffic-lighted intersection), the level of service was

investigated. The results showed congestion indices of 90% - 100% and more. On this basis, it

was decided to design a complex devise that offer a better level of service (flow between the

fluid and the satisfactory). In fact, the whole area of intersection was designed with a large

roundabout, a cycle path, bus stops and all the necessary pedestrian crossings.

In the light of the safety analysis (road accidents and speed measures), in order to ensure

an adequate level of safety for both vehicles and pedestrians, all the appropriate horizontal

and vertical signs have been provided; vehicle and pedestrian routes have been rationalized

and highlighted (e.g. maintaining the colour of the cycle path for crossings); measures have

been taken against architectural barriers; high standards of brightness and visibility have been

guaranteed for the road luminance and especially for pedestrian crossings and finally, the

vehicular flows at the intersection were channelled through specific divisional islands in order

to avoid hazardous maneuvers.

DATA AVAILABILITY

The traffic data used to support the findings of this study are included within the article.

CONFLICTS OF INTEREST

The authors declare that there is no conflict of interest regarding the publication of this paper.



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