INFRASTRUTTURE STRADALI E SMART ROADS

Knowledge and understanding

The course aims to provide students with the knowledge required for the design of road infrastructure, with particular reference to the geometry of road alignments and to the verification of safety and operational conditions. On completing the course, students will have acquired knowledge and understanding of the theoretical and regulatory principles governing road design, with reference both to national standards and to the most advanced performance-based verification procedures for road projects.

Applying knowledge and understanding

Students will be able to apply the knowledge acquired to the design of road infrastructure, independently developing geometric alignment solutions and carrying out the safety and operational verifications required by national standards and by performance-based verification procedures. Group design work will also enable students to develop cooperative working skills and to gain competence in the use of advanced design software tools.

Making judgements

Students will develop the ability to critically evaluate design choices, comparing alternative solutions in terms of the safety, functionality and sustainability of the infrastructure. They will be able to interpret the results of performance-based verifications and to form independent judgements on the adequacy of road projects with respect to regulatory requirements and real operating conditions.

Communication skills

Students will be able to present and justify their design choices with appropriate technical language, both in written form through the preparation of design documents and orally in presenting and discussing their work. Group work will further foster the ability to communicate and collaborate effectively within a design team.

Learning skills

Students will have acquired a method of study and work that will allow them to independently update their competences in line with the evolution of technical standards, software tools and design and verification methodologies for road infrastructure, so as to approach subsequent educational and professional pathways with autonomy.

The course is delivered through lectures, in-class tutorials and the preparation of technical reports and design deliverables.

Lectures, supported by teaching materials and presentations, introduce the theoretical foundations of the geometric and functional design of road infrastructure and of smart road technologies.

In-class tutorials, of an applied nature, guide students in applying design standards and calculation methods to practical cases.

A significant part of the activity is devoted to the development of a design project concerning the layout of a road alignment, carried out in small groups, which requires the integrated application of the acquired knowledge and concludes with the preparation of a technical report and the related drawings — presented and discussed — using specialised design software (i.e. Civil 3D).

INTRODUCTION TO THE COURSE

The roads in the history and evolution of design criteria. Functional aspects, road safety, and environmental issues. Design according to standards and performance-based design.

ROAD INFRASTRUCTURE

The new Highway Code and Decree of 05/11/2001. Functional classification of roads. Issues related to the classification of the existing road network. Roadway: Road section, platform, carriageway, road structure.

ROAD DESIGN BASED ON STANDARDS

Ministry of Infrastructure and Transport, Decree of 05/11/2001: Functional and Geometric Standards for Road Construction. Organization of the road: cross-section, additional lanes, marginal elements. Widening on curves for vehicle alignment and obstacle visibility. Road axis geometry: Design speed. Tire-pavement contact and coefficient of friction values. Clear visibility distances (stopping, overtaking, lane changing). Vehicle movement along circular curves. Minimum radius and criteria for determining platform slope, tangents, variable radius transitions, design, and insertion of clothoid transitions. Compositional criteria of the road axis and planimetric coordination of geometric elements. Criteria for the placement of speed bumps. Maximum uphill and downhill gradients. Critical length of speed bumps. Insertion of lanes for slow vehicles. Vertical transitions. Planimetric-altimetric coordination. Design speed diagram. Speed of slow vehicles. Route verification based on speed diagrams.

PERFORMANCE-BASED ROAD DESIGN

Safety performance: The European and national framework for road safety. The European directive on road infrastructure safety management and Decree of 15/03/2011. Direct measurement of road safety and performance indicators: Road safety performance functions. Poisson and Negative-Binomial distributions. Accident modification factors. Empirical Bayesian correction. Estimation of expected accident numbers and comparative analysis of different design solutions. Direct and indirect costs of road safety. Discounting of costs and benefits. Benefit/Cost ratio. Indirect measurement of road safety: Design speed, commercial speed, legal speed limit, and operational speed. Operational speed and geometric consistency of the route. Pre-project safety checks. International reference framework and National Guidelines.

Traffic performance (overview): Evaluation of service level for design practice. HCM model (single-lane or separated-lane roads). Free-flow speed. Measures of effectiveness (average travel speed, percentage of time in congestion, traffic density).

ROADWAY FURNISHINGS

Definition of the clear zone and protective zone. Safety performance related to road margins: clear zone width, slope of embankments, presence of fixed obstacles, types of safety barriers. Influence of vehicle characteristics and swerving modes on collision consequences. Types of safety barriers to be adopted, their location, related complementary works, regulatory framework, and EN standards.

SMART ROADS

The physical and digital infrastructure of Smart Roads. C-ITS solutions day 1.0 and beyond. Definition of Operational Design Domain and Service Level of Smart Roads. Levels of vehicle autonomy on the roads.

ROAD GEOTECHNICS (Overview)

Construction of the roadbed. Physical characteristics of soils. Particle size analysis. Soil composition: specific gravity, void ratio, porosity. Measurement of water susceptibility: Atterberg limits. Soil classification. Group index, CNR-UNI 10006 Classification. Volume of the roadbed solid. Area and volume diagrams. Compensation worksites.

ROAD PROJECT DEVELOPMENT

Design levels, basic cartography, alignment study. Executive design: typical sections, layout plan, project layout, layout of hydraulic presidio works, longitudinal profile, cross-sections, notebook of sections, and detailed volume calculation. Construction details of vertical transitions, construction details of art structures, general cartography, project report. Computer-aided design.

-Lamm, Cafiso et alt. “How to make two lane rural roads safer”,Witpress, 2007

- Highway Safety Manual. AASHTO, 2010

The assessment of learning is based on an optional in-course (mid-term) oral test, a final oral examination and the evaluation of the deliverables of an assigned road section design project. No written tests are envisaged: assessment is carried out through an oral interview with open-ended questions, aimed at evaluating knowledge of the contents, the ability to apply it and command of technical language.

Registration. Registration for the final examination is made through the University portal, in the sessions published in the examination calendar; registration for the in-course test is made by e-mail to the lecturer, within the deadlines indicated during the lectures.

In-course oral test (optional) — weight 35%. It is held during the teaching period and covers sections A, B and E.5 of the list of examination topics. It consists of an interview lasting approximately 20–30 minutes, with a number of open-ended questions. Passing the in-course test exempts the student from the corresponding topics in the final examination.

Final oral examination. It covers all the topics in the list of examination questions and has a weight of 70%; for students who have passed the in-course test, the final examination covers only sections C, D and E and has a weight of 35%. It consists of an interview lasting approximately 30–45 minutes, with open-ended questions and discussion of the design deliverables.

Design project — weight 30%. Submission of the deliverables relating to the assigned road section design project is mandatory and is a prerequisite for admission to the final examination. The deliverables must be submitted within the deadlines agreed with the lecturer and are presented and discussed during the oral examination.

Grading scale. Marks are expressed out of thirty. The examination is passed with a minimum mark of 18/30; the maximum mark is 30/30, with the possible award of honours (cum laude). The final mark is determined by the weighted average of the tests according to the weights indicated above (in-course test 35% + final examination 35% + project 30%, or final examination 70% + project 30% in the absence of the in-course test). Attendance and active participation in the teaching activities are positively taken into account.

Road infrastructure

1. Functional classification of roads — Functional classification of roads (Highway Code and Ministerial Decree 2001)
2. Organisation of the road cross section and design speed range
3. Organisation of the road cross section: type and dimensions of the platform elements
4. 2+1 layout (type)

B) Standard-based road design

1. Resistances to motion
2. Longitudinal and transverse skid resistance coefficients and factors
3. Driving task and Human Factors
4. Stopping sight distance
5. Overtaking (passing) sight distance
6. Sight distance on curves
7. Variation of speed and cross slope (superelevation) as a function of the curve radius (Rmin, R* and R2.5)
8. Minimum-radius formula and definition of the calculation parameters (skid resistance, cross slope, speed)
9. Determination of the design speed given the curve radius
10. Homogeneity of the geometric elements of the horizontal alignment
11. Behaviour of the edge lines (transition, inflection, continuity)
12. Dimin and Dimax
13. Driving dynamics along the clothoid
14. Geometry and setting-out parameters of the clothoid
15. Minimum and maximum parameter of the clothoid
16. Spiral curve length (AASHTO)
17. Inflection clothoid (reverse-curve spiral)
18. Continuity clothoid (compound-curve spiral)
19. Variation of cross slope in the absence of a clothoid (AASHTO)
20. Vertical alignment, water drainage and positioning of culverts
21. Longitudinal grade and critical grade length
22. Speed of slow vehicles and insertion of auxiliary (climbing) lanes
23. Vertical curves
24. Horizontal–vertical (plano-altimetric) coordination

C) Performance-based road design

1. Safety analysis (Safety Audit, Safety Inspection)
2. Safety indices (crash number, frequency, rate)
3. Safety Performance Functions: SPF and Empirical Bayes correction
4. HSM model: SPF under base conditions
5. HSM model: CMF
6. Definitions and applicative differences of the concept of speed
7. Design Consistency
8. Fundamental parameters for calculating the level of service of a road

D) Functional roadside equipment

1. Selection and positioning of safety barriers
   1. Performance indices of the safety barrier, including those relating to the safety of vehicle occupants
   2. Quantities relating to the deformation of safety barriers
   3. Installation length
   4. Clear Zone and protection of lateral obstacles