We live in an environment where transport strategies set objectives that traffic engineers have to achieve in practice. Often, despite the best efforts of engineers these goals are not being met. In bus priority, for example, traffic engineers are often required to obtain journey time savings set by policy makers of 10-20%. Modelling using TRANSYT, micro-simulation, etc can resolve this problem however this can involve substantial data collection, and time in validating and running the model. There is therefore a need to develop a simple method of assessing possible journey time savings on a length of road; a simple method, which can be used at the feasibility stage and can feed through to those preparing the overall objectives.Using a spreadsheet based system, a method has been developed to identify problems on the traffic network and to suggest achievable journey time savings. To achieve this the route is broken down by delay features creating a series of links and nodes. Delay characteristics are assigned to each feature. Using these attributes and the distances between features, the journey times can be calculated based on acceleration/deceleration profiles of different vehicle types. The model compares theoretical 'optimum' journey times with actual journey times to identify areas where route performance can be improved. The model also allows feature specific and/or whole route improvement schemes to be assessed, to help in determining which initiatives are likely to provide the most economic solution to improving journey times. The paper will explore the policy background that has necessitated the development of the model, and its theoretical basis. The paper will also outline the how the model has been validated against observed route performance data and its initial application as a system to develop bus priority schemes and to compare the possible saving of LRT versus bus. For the covering abstract please see ITRD E135207.
Abstract