For a number of years, I have worked in the Traffic Management. When construction works start on a road, it is the traffic management department that is in charge of making sure that the construction phases of the work minimizes disruption to the flow of traffic and maximizes safety for both the traveling public and the safety of the work force.
Traffic Management - by its nature - is a very fast paced and every changing job. The work flow from one day to another is never the same. That’s why we rely heavily on computer applications that can help us make complex calculation in a matter of minutes.
There are a lot of factors that come into traffic management that have to be considered every time a new temporary traffic scheme is implemented. The weather, the condition of the existing road surface, current traffic flows, predicted traffic flows, driver visibility - to name a few.
Using AutoCad as a base program allows us to use add on software packages, ranging from temporary safety barrier design, traffic sign design and all the way through to traffic modeling. This is more than useful when you have to make quick fire decisions.
Using all of the software that is available to us we are able to visualizes the impact of any major road works before the scheme is implemented on the road. A typical day working in the traffic management industry would be as follows. (Based on a major road upgrade or repair project.)
The construction team and the traffic management engineers will have a meeting to discuss the planned construction phases of the work. Once a phasing plan has been agreed upon, the traffic management engi-neers will then sketch temporary road layouts that will allow the construction to take place. The temporary road layout will maximize safety for both the road users and the construction teams. Once the safety of everyone has been taken into consideration, this ideal temporary road layout has to be designed, tested, and audited for safety before it goes on the road. This process relies heavily on AutoCAD.
OS mapping will be loaded as an x-ref into a new drawing. Next, the design drawings for the new road will be overlaid onto the OS mapping. These x-ref’s can be up to 40mb+, so it is essential that all the traffic management technicians have work stations that are spec’d well above the minimum requirements of the software. Once all the information is loaded into the drawing, the temporary traffic management is then de-signed. It is important to try and utilize as much of the existing carriageway as possibly whilst giving as much room as possible to the works area. If this becomes unachievable then a temporary section of road may have to be constructed before the new permanent road can be constructed.
Once the temporary road layout has been designed using miles of polylines and a hand full of hatching, the technicians will then turn to the add on software packages to turn the design into a detailed design drawing.
Temporary road signs will be designed, tested, and given a safety factor rating. Once they have been ap-proved by the safety auditors they will be sent for manufacturing. They will then be used to safely guide traffic through the road works. Along with the road signs, temporary road markings will be designed at this stage to further aid the public.
The polylines that were created earlier will now be used as setting out points for safety barrier and traffic cones that will create a safe working zone. Using another add-on package, the technicians will specify which type of safety barrier that is to be used. This will depend on the speed limit that is imposed on the road. A road with a high speed limit will need a specific type of safety barrier that has a larger deflection zone. This must be taken into consideration when planning the works area as the deflection zone must be kept clear at all times. Traffic cones will be placed alongside the barrier as the reflective sleeves keep drivers alert to the presence of narrower lane width and the barrier.
Completed, the drawings will show;
- The construction working area made available.
- The new alignment of the traffic.
- A cross section of the layout.
- All equipment details (traffic cones, temporary road markings and temporary signs.
A software package that will analyze the road width and the radius of corners to ensure that larger vehicles can pass through the road works. When narrowing traffic lanes down to 3.0m it is essential that this software if used to check that large haulage vehicles can physically fit though the road works site. The last thing anyone wants is a large vehicle wedged between 2 sections of safety barrier. In addition, practical wide loads are normally re-routed to avoid the works site.
The drawings when complete will then be run through a traffic flow simulation package. This will allow the traffic management engineer to visualize the impact of reducing the road’s traffic capacity. When existing traffic flow information is entered and the software is run, it shows blocks of cars ‘driving’ along the pol-ylines that were created earlier. It will then highlight potential areas of queuing traffic, or worse - potential accident areas.
Once the traffic management engineers are happy with the results of the simulations, the traffic management scheme is implemented on the road.
This process can take anywhere from two days to two months to plan, design, and test.
This, of course, is the idea world scenario. In practice, as with most design/engineering industries, it needs to be done yesterday. Using AutoCAD and the add-on software packages, traffic management technicians have a seamless work flow that can be flexible and adapt in a fast paced environment.