Abstract
In this study, the traffic parameters were collected from three work zones in Iran in order to evaluate the queue length in the work zones. The work zones were observed at peak and non-peak hours. The results showed that abrupt changes in Freeway Free Speed (FFS) and arrival flow rate caused shockwaves and created a bottleneck in that section of the freeway. In addition, acceleration reduction, abrupt change in the shockwave speed, abrupt change in the arrival flow rate and increase in the percentage of heavy vehicles have led to extreme queue lengths and delay. It has been found that using daily traffic data for scheduling the maintenance and rehabilitation projects could diminish the queue length and delay. Also, by determining the bypass for heavy vehicles, the delay can be significantly reduced; by more than three times. Finally, three models have been presented for estimating the queue length in freeway work zones. Moreover, the procedure shown for creating a queue length model can be used for similar freeways.
Highlights
Road maintenance and rehabilitation require the creation of work zones
According to our investigations, each work zone in a specific freeway has its own queue length model, but the procedure shown for creating a queue length model can be used for similar freeways
After evaluating the traffic parameters and modelling of queue length in Karaj-Tehran freeway work zones, the following conclusions have been drawn: –– The results have shown that factors such as acceleration reduction (a) and shockwave speed (Wu) which were more intense in Wsork zones 1 and 3, respectively, were effective in their queue moldels. –– The workzones that have taken place nearer the peak hour and with higher percentage of heavy vehicles, have featured significantly more delay. –– At the peak time and if the traffic demand exceeds the service capacity, it caused shockwaves and created a bottleneck in that section of the freeway
Summary
Road maintenance and rehabilitation require the creation of work zones. Work zones on freeways lead to traffic disturbances and delays which causes an increase of the time of travel, vehicle depreciation and fuel consumption [1]. On freeways and urban highways, the maintenance and rehabilitation projects result in creating long queues especially during rush hours. In the developed countries many studies have been conducted or are being carried out on the causes of creating queues [2, 3, 4] while in the developing countries, this has been less considered. By considering the increasing number of vehicles and maintenance and rehabilitation projects, the necessity to study the creation of queues is increasingly emphasized [5].
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