Abstract
The main elements of urban transport infrastructure include: the street network with intersections, bridges, viaducts, flyovers, vehicular traffic tunnels. Unsignalized four-leg intersections and roundabouts is the largest “saturated transport flow” of the street network. Roundabouts which were designed as far back as 1970–1980 were well-functioning when the car ownership level was 180–200 veh/1000 inhabitants. Currently, when the level of car ownership comes to 520–560 veh/1000 inhabitants, unsignalized roundabouts operate in the “oversaturated flows” regime. The research results of the Vilnius Gediminas Technical University and other universities showed that when designing new or reconstructing existing intersections the indicators of territorial planning, transport planning, environmental protection, traffic safety should be considered. As a common indicator for assessing all other indicators a monetization (estimation in monetary terms) should be used. When preparing projects for intersection reconstruction it is recommended to apply a new method of intersection analysis and evaluation based on the principles of sustainable development of urban transport infrastructure.
Highlights
A system of road transport should operate safely, it should not contaminate environment, use small amounts of fuel and have an ability to quickly and reliably carry passengers and cargo
The paper suggests methodology for calculating capacity and efficiency of roundabouts as of important component of transport infrastructure based on modern principles of sustainable urban development and taking into consideration the impact of pedestrian flows, time spent by vehicle in the intersection, number of accidents and conflict points depending on roundabout diameter and “weaving” of flows when moving in a circle
When preparing new projects of urban transport infrastructure objects – street segments, intersections, traffic control, traffic-light control and management it is necessary by applying the sustainable urban development principles to assess the intersection capacity and the territorial planning, ecological and traffic safety indicators
Summary
A system of road transport should operate safely, it should not contaminate environment, use small amounts of fuel and have an ability to quickly and reliably carry passengers and cargo. In order to increase the urban roundabout capacity and to improve traffic safety new roundabouts are installed or four-leg intersections, the effectiveness of which is not sufficient, are reconstructed. The specific objective of this paper (Zirkel et al 2013) is to quantify the relationship between crash rates, sight distance parameters, and operating speeds to present an approach to establishing performance-based standards that highway practitioners could adopt in roundabout design. Capacity models based on the gap acceptance theory are widely used in unsignalized intersections and roundabout capacity analysis. The present analysis is based on either gap acceptance models or empirical models These models do not properly account for the impact of origin-destination flows on roundabout operations. Compared to typical trafficlight controlled intersections, in roundabouts the work of traffic and pedestrian flows increases, as well as the time of vehicle movement in the roundabout, large land areas are required (4000–7200 m2) for the construction of roundabouts and this under high prices of land in the central part of the city (the price of 1 are of land is ~ 60 000 EUR) increases the total cost of roundabout construction
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