Rodrigo Troncoso

Límites de la tarificación vial

Para muchos academicos y profesionales de la ingenieria de transporte, el concepto de tarificacion por congestion se ha transformado en el paradigma de la eficiencia en el uso de la escasa infraestructura vial y del desincentivo al uso excesivo del automovil. Si bien la tarificacion vial puede ser, en varios casos, una buena herramienta de gestion de trafico, comporta tambien una serie de riesgos y sobreexpectativas que es importante tener en consideracion a la hora de disenar, implementar y administrar un eficiente esquema de tarificacion vial. En este trabajo presentamos una serie de antecedentes, basados muchos de ellos en la literatura especializada y en evidencia empirica, que permiten describir los riesgos potenciales y eventuales sobreexpectativas que enfrenta una politica de tarificacion por congestion, lo que puede ser de gran ayuda para impulsar una correcta implementacion de esta politica de gestion de trafico.

Estimates of price elasticity of demand for urban freeway use with high-frequency control variables: the case of Santiago, Chile

Estimates are presented of toll and fuel price elasticities of demand for urban freeway use in Santiago, Chile. High-frequency toll and vehicle data were collected from four urban freeways for different route segments and times of day. Estimation was performed using log-linear regression models whose explanatory variables were tolls, fuel prices, city traffic levels and sets of dichotomous variables to control for daily, weekly and monthly seasonality. City traffic is a high frequency control of the activity level of the city. The elasticities to changes in tolls and fuel were all low in absolute value. The toll elasticities were below 0.05 for two freeways and 0.16 for the third, while for the fourth, which had more alternative routes, it was 0.47. The fuel price elasticities were also heterogeneous, with values of approximately 0.45 for two freeways and 0.21 for the third whereas for the fourth, which had the fewest alternatives, it was 0.07.

Estimating the impact of incidents on urban controlled-access highways: an empirical analysis

ABSTRACT An empirical analysis is developed that quantifies the impact of different types of traffic incidents on the speed and maximum flow averages of vehicles on a controlled-access highway. The incident types considered include damage to highway infrastructure, vehicle rollover, crashes (into stationary objects), collisions (with moving vehicles), rain, fog, vehicle breakdowns, pedestrians on roadway, etc. Using real-world data from Chile’s most heavily used urban motorway/freeway, estimates of incident impacts on speed are generated using a multiple linear regression model incorporating instrumental variables to correct for endogeneity. Flow results are then generated using the fundamental traffic equation relating speed, flow and density. A ranking of the impacts on highway traffic of the different incident types based on incident frequency as well as impact size demonstrates that for the real case studied, the incidents with the greatest cumulative effect are (in order of magnitude) vehicle breakdown, collisions and rain.