Evaluation of safety performance in urban networks: a case study of Fortaleza city/Brazil

Caio Assunção Torres
Flávio José Craveiro Cunto

Road safety performance is usually not objectively considered in traditional transportation planning process due to a myriad of problems regarding the methodologies to estimate the number of accidents on urban transportation networks. Conventionally, efforts regarding the assessment of road safety performance have been accomplished with the use of safety performance functions (SPF). This type of statistical modeling approach has been very useful when focused on isolated road entities such as intersections and road segments, mostly because it can reasonably deal with some of the stochastic problems related to the rare and random nature of crashes. Advances in data collection and spatial manipulation as well as modeling techniques have been fostering studies to support the use of SPF for safety assessment of urban networks. This paper investigates the use of SPF as a tool to evaluate different transportation planning scenarios for urban road networks. Initially, a geographic crash database, geometric and operational attributes of the network database were consolidated on a Geographic Information System (GIS) platform and then used for developed SPF for links (road segments) and nodes (intersections) of the urban road network of Fortaleza city, Brazil. Calibrated functions were implemented on a sample network modeled using macroscopic model TransCAD. A residual analysis was performed using observed and estimated crash frequency. Finally, tree hypothetical scenarios were applied to the network in order to explore the sensitivity of the safety performance obtained from this modeling exercise. The results shows that possible to plan for the implementation of additional measures to minimize the increase in crashes for the critically affected in road network, links and nodes within SPF. Some important pitfalls and limitations in the application of SPF on computerized transportation networks were highlighted in the research. The most important is the dependence of estimation of accidents with AADT of the estimation process Although additional work needs to be done regarding the integration of traffic safety models into the urban transportation planning process, the product of this research should help other researchers pursue interesting and useful areas of research that would help, at the planning stage, to reduce the number and the severity of collisions on urban roads.



Shipping and the environment – research meets reality

Centre for Transport Studies (CTS) in co-operation with Ports of Stockholm invite you to the seminar Shipping and the environment – research meets reality.



Simulation of cut-in by manually driven vehicles in platooning scenarios

A study in a VTI-driving simulator has showed that a platoon will be able to handle a cut in from a manually driven car. The results of this study have recently been presented at two conferences in Japan.



The five-year anniversary of European Road Profile Users' Group (ERPUG) Forum will take place at Ramboll head quarter, Copenhagen, Denmark October 19-20, 2017.


Self-driving buses in Sweden next year?

A self-driving, fossil-free bus. This idea might become reality through a forthcoming collaborative project involving the Swedish National Road and Transport Research Institute (VTI), Linköping University and several other participants. The project group aim...


New climate-proof solutions for hard surfaces in cities

High-density road infrastructure that emphasise maximum durability and minimum maintenance create inflexible systems, which put increased stress on urban trees and lead to increased risk for flooding. Over the past five years, the ‘Climate-proof solutions for...


VTI is preparing for automated vehicles

Automation of traffic systems will lead to major changes. The European Union’s (EU) CoEXist research project began in June 2017 with the aim of preparing cities and road operators for the introduction of self-driving vehicles. The Swedish National Road and...


Vehicle Driver Monitoring: sleepiness and cognitive load

To prevent road crashes it is important to understand driver related contributing factors, which have been suggested to be the critical reason in 94 per cent of crashes. The overall aim of the project Vehicle Driver Monitoring has been to advance the...