Use of IT tools in Road Management and Engineering.

Use of IT tools in Road Management and Engineering

Raymond Au

Abstract

The report presents the use of IT tools in the road management and engineering area. IT tools used in the road management and engineering area is the main approach worldwide. It can save time, cost, labor force and also perform some works that human may not be able to accomplish. HDM-4 and ARCADY are typical examples of computer programmes. HDM-4 aims at assisting engineers in predicting the future economic, technical, social and environmental outcomes of possible investment decisions concerning road assets. It provide assessments of the economic and environmental impact of investment choices and consider new development works, maintenance works and improvement works as possible investment choices. ARCADY can assist engineers in predicting accident rates in existing roundabouts and designing new roundabouts at an ordinary intersection. It can save much precious time for engineers in geometric design in avoiding iterations by hands. Examples of testing these two computer programmes were performed. They justify the validity of both computer programmes in the road management and engineering area. However, nothing is perfect and the computer programmes also have drawbacks which will be discussed in this report.

Contents

1.0 Introduction

IT tools are widely used in many fields now. In the road management and engineering field, IT tools are especially vital and useful because road congestion and road accidents attribute billions of dollars in a country each year. For economical and environmental issues, uses of IT tools can efficiently reduce the social and economic loss due to the congestion and accidents, and mitigate the environmental impact from vehicles.

The Highway Development and Management Tools (HDM-4) is a software system for investigating choices in investing in road transport infrastructure. It was developed on the basis of HDM-3. These choices may include developing new roads, improving existing roads, maintaining existing roads, introducing new vehicle technology and introducing new ways for funding and managing road assets. It will enable managers of road network assets to investigate the possibilities for providing cost-effective development and upkeep of their road system, which brings benefits to the communities that they serve.

ARCADY is a popular computer programme for designing roundabouts in UK. It can design a new roundabout at an intersection; predict capacities, queue lengths, delays and accident risk at existing roundabouts. It is very important in road engineering for designing roundabouts quickly since time is very important in an engineering field.

2.0 HDM-4

HDM-4 is a decision support software system for assisting road managers to predict future economic, technical, social and environmental outcomes of possible investment decisions concerning road assets, and consider new development works, maintenance works and improvement works as possible investment choices and allow to consider investments on a single section of road, or a large network of road links (many sections), or any combination of road sections in a sub-network. For example, traffic volume and composition, deterioration of the road condition, the effect of works on road condition, the effect of the investment on vehicle emissions and the effect of condition and road works on road users, in terms of vehicle operating performance and costs, road user and cargo time delay and costs, accident rates and costs can be predicted.

2.1 System Architecture

The HDM-4 technology can be integrated with present and future road management systems. It has been developed at three levels which are the knowledge and algorithms embodied in the modelling of technical, and economic performance of road infrastructure, the program modules which deliver the models in explicit terms, and the HDM-4 software, including the modelling modules, which provides the investment analysis and works programming functions (PIARC, 2000).

The system architecture consists of a database, data managers, models and analysis tools. A database manages the input data and analysis results while data managers are ...

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2.1 System Architecture

The system architecture consists of a database, data managers, models and analysis tools. A database manages the input data and analysis results while data managers are software which provides the user interface and controls data. Models are software modules which reflect modeling algorithms, and analysis tools controls the system application (PIARC, 2000).

2.2 Road Management Functions

The HDM-4 provides a powerful system for the analysis of road management and investment alternatives. The system can be applied to road management, programming road works, estimating funding requirements, budget allocations, predicting road network performance, project appraisal, policy impact studies and a wide range of special applications.

2.2.1 Planning

HDM-4 can analyze the road system as a whole in medium to long term, or strategic, estimates of expenditure for road development and preservation under various budget and economic scenarios. Predictions can be made of road network conditions under different funding levels in terms of key indicators together with forecasts of required expenditure under defined budget. The results of the planning exercise are of most interest to senior policy makers in the roads sector in both political and professional means. The HDM-4 application in the planning level is always performed by strategy analysis.

2.2.2 Programming

Programming involves the preparation of multi-year roadwork and expenditure programmes in which sections of the network needs maintenance, improvement or new construction, are selected and analyzed. Ideally, cost-benefit analysis should be undertaken to determine the economic feasibility of each set of works. The programming activity produces estimates of expenditure in each year, under defined budget, for different types of roadwork and for each road section. The HDM-4 application in the programming level is programming analysis.

2.2.3 Preparation

This is the short-term planning stage where road schemes are packaged for implementation. At this stage, designs are refined and prepared in more details; bills of quantities and detailed costing are made, together with work instructions and contracts. Detailed specifications and costing are defined, and detailed cost-benefit analysis can be carried out to confirm the feasibility of the final scheme. The HDM-4 application in the preparation level is project analysis.

2.2.4 Operations

Decisions about the management of operations are generally made on a daily or weekly basis, including the scheduling of work to be carried out, monitoring of labours, equipments and materials, the recording of work completed, and use of this information for monitoring and control.

3.0 ARCADY 5

ARCADY (Assessment of Roundabout Capacity and Delay) has been developed over the last 20 years by TRL (Transport Research Laboratory) and is used for predicting capacities, queue lengths, delays and accident risk at roundabouts. ARCADY is a user friendly and helpful tool to aid the busy traffic engineer in designing new roundabouts as well as assessing the effects of modifying existing designs. It can design a roundabout and predict the accident rates automatically within a short time. It can also avoid the iteration process by hand to save much time. Thus, ARCADY is very convenient and important in road engineering.

ARCADY 5 is the most recent evolution of a program that has been successfully used to design and re-design thousands of roundabouts throughout the world. ARCADY 5's main platform is graphical under standard Windows* environment, which is common to many organizations including governments, multi-national organizations and universities. ARCADY is based on empirical relationships derived from the study of many UK roundabouts. The capacity relationships were established from a database covering 11,000 minutes of at capacity operation at 86 roundabout entries, and the accident prediction routine is based on 431 injury accidents at 84 roundabouts. Capacity and injury accident rates are linked directly to intersection geometry. The entire UK government, funded research programme, carried out at TRL, cost some and 7.5m or US$ 11.5m at today’s values, and gives ARCADY robustness (TRL Software Bureau, 2003).

4.0 Test of HDM-4 and ARCADY-5

4.1 HDM-4

In the Highway Development and Management Series, Kerali (2000) presented an example of the analysis of HDM-4. The national road authority has drawn up a list of candidate road sections for periodic maintenance and improvement over the next three years in Western Province. The list of candidate road sections follows a review of pavement condition surveys carried out by consultants. There is a policy that the candidate projects are prioritized and selected for the maintenance programme in the three-year budget period. The objective of the task is to prioritize the candidates according to the economic benefits basis.

The HDM-4 imports data from the Pavement Management System or use the HDM-4 Road Network manager to create the candidate road sections. It also defines the characteristics of the vehicles that use the road network and specify the traffic growth rates. The maintenance and improvement standards are assigned to the candidate road sections together with the unit costs. Afterwards, the road works can be determined. The unconstrained work programme results give the total funding required for the list of candidate road sections. Finally, HDM-4 can carry out the budget optimization to prioritize and select the short list of projects that can be carried out within the available budget.

4.1.1 Results

The analyses indicate that the selected road sections for periodic maintenance and road improvement would require approximately US$11.345 million over the three year budget period.

4.2 ARCADY 5

ARCADY calculations can be applied to single island roundabouts with up to seven arm. The user has a choice of methods of entering traffic flows and the program can estimate the shape of the peak according to the amount of data available. The safety of a design can be tested using ARCADY's accident predictions. Accident prediction is available for all conventional and mini-roundabouts layouts. The program can be applied to single-island roundabouts with 3 to 7 arms and now mini-roundabouts. Both at-grade and grade-separated roundabouts can be modelled. Pedestrian crossings (zebra crossing type) can be included, and the queue lengths can be viewed, animated and printed.

Roundabout capacity studies by Highways Agency’s Compendium of Research from 1993 to 1996 with the project value of ￡300,000 was carried out to check the continuing validity of the existing ARCADY relationships for conventional roundabouts and to derive capacity relationships for mini-roundabouts. The outputs were to be implemented in a new release of ARCADY incorporating both capacity and accident relationships for mini-roundabouts. It is 15 to 20 years since the capacity relationships used in the ARCADY computer program were established; corresponding capacity relationships for mini-roundabouts have never been separately determined.

4.2.1 Results

The checks on capacities at conventional roundabouts have been found to be still valid (Highways Agency’s Compendium of Research, 2003). Minor areas where further research work could give useful benefits have been identified. Related work on mini-roundabouts was brought to a successful conclusion.

5.0 Discussion

The main approach of HDM-4 is usually biased to the economic approach because it is mainly applied in the network and program level which focus on the economic area. Therefore, it may not be very practical in real situation. For example, when evaluating the maintenance of a pavement in a long term period, it may estimate that the pavement only needs one major rehabilitation in the period. However, it is impractical to have a large funding for the rehabilitation in a short period such as one year. It may not be allowed in such a large amount such as millions of pounds in a year. Therefore, in practice, a major rehabilitation should be modified to several smaller ones around that period. It may be easier for funding in several times for several rehabilitations over a longer period. That shows planners or engineers must ensure the results obtained from HDM-4 practical in real before implementation because computer programmes can only give us the results under ideal conditions which are always impossible in our real world. Also, another drawback for the application of the HDM Model is the availability of adequate data. It is important that the highway agencies realize how critical it is to collect and process the required data in order to produce sound results. A specific budget should be assigned for this task if consistent and serious results are wanted. Collection of data is an expensive activity and it may not be possible for every road assets.

ARCADY was justified to be still valid for different types of roundabouts. It can effectively assist highway engineers in assessing the existing roundabouts for safety or any possible improvement, and designing a new roundabout from an ordinary intersection in order to alleviate the heavy right turn movement. It also includes crash prediction model based on UK equation. The software is backed by TRL and thus the validity of it can be ensured by numbers of research. However, it required detailed knowledge of geometrics such as approach length, approach curvature and entry width and so on. It is also restricted to about 50% confidence limits and the calibration to U.S. capacity is still unknown at this time.

6.0 Conclusions

IT tools bring many advantages and convenience to our lives. It shortens the gap between people and time required from place to place. It makes the world run faster with better quality. . They always play major roles in many fields such as construction, banking and design, etc. There are many computer programmes used for road management and engineering. HDM-4 and ARCADY are typical examples in this field. HDM-4 mainly performs it’s functions in road management in making decision for the future improvement of road assets in network and project level. It can predict the different impacts. Making decision related to cost is very important since budget is always limited and so prioritization is always necessary. The prioritization can be determined by HDM-4, and the budget and resource can be effectively allocated. ARCADY can perform its functions in road engineering in geometric design and accident rate prediction. It has the advantages of time saving, accuracy and clear presentation over human capability in design by hands. Accuracy is very important in geometric design since it can directly affect the road users. Therefore, it can increase the degree of road safety which is always the most important issue in road traffic. ARCADY has been developed to ARCADY 5 and this latest version was tested to be still valid in performing its functions effectively. Practical uses of both computer programmes also show their validities in the areas in many projects but further analyses are still necessary for overcoming the drawbacks.

7.0 References

TRL Software Bureau (2003). ARCADY 5. retrieved from

Highways Agency’s Compendium of Research (2003). Projects: Roundabout capacity studies. Retrieved from

PIARC (2003). HDM-4 approaches to road investment analysis. Retrieved from

Kerali, G. R. (2000). Example of HDM-4 Programme Analysis Application. Highway Development and Management Series. Vol. 1. p.32-33