Every year, accidents in the roadways around construction and work sites cause hundreds of fatalities. Temporary traffic control, also called TTC, is the effective use of a variety of devices and personnel to guide drivers safely through areas where road conditions have been changed – most frequently by a traffic incident or by work in progress.
Civil engineers should understand the basics of setting up a temporary traffic control zone around a work zone to facilitate the safety of project personnel and drivers. Effective work zone traffic control requires the development of a temporary traffic control plan that facilitates safe work while maintaining and protecting the flow of traffic.
Temporary traffic control is both a tactical and strategic concern. It requires deep knowledge of worksite conditions and the insight to utilize temporary traffic devices and personnel effectively. Most traffic control plans involve multiple interconnected approaches and may be divided into several phases depending on the nature of the project.
The Purpose of Work Zone Traffic Control
The main purpose of work zone traffic control is safety – that of the workers and of people who must use the affected roadways in their daily lives. This is a paramount concern that must come before all others. However, it is not the only consideration involved.
Work zone traffic control has a number of important secondary effects when done well:
- Cost Control: Greater safety reduces both direct and indirect project costs. It cuts down on the overall cost of insurance for similar projects and also helps ensure workers are not unnecessarily exposed to overtime or night working conditions that can be more hazardous.
- Constructability: An efficient approach to work zone traffic control minimizes delays and disruptions overall. This can have a significant impact on the timeline of any given project, which in turn enhances profitability and contributes to future projects.
- Traffic Delays: While planning for traffic control, professionals should remain cognizant of the impact on the community. Traffic delays can have a ripple effect that might impact businesses and families throughout the region, and should be minimized when possible.
- Legal Liability: Both the municipal authority and the project principals face liabilities for the duration of a project. Even the most minor injury incident is not acceptable. Best practices must not only be followed, but documented, in every step of the process.
Major Principles of Work Zone Traffic Controls
The three major goals of work zone traffic control – safety, mobility, and constructability – are, unfortunately, competing aims. Even under ideal conditions with effectively limitless resources, actions in one area will inevitably limit what can be achieved in the other areas.
Since it simply is not possible to achieve 100% safety, mobility, and constructability, a balance must be struck between these interests – preferably one in which all stakeholders work together to reach their mutual objectives and safety leadership is not seen as an obstacle to progress.
On a day-to-day operational level, traffic control should strive for all the following:
- Predictable, reasonably unhindered movement of pedestrians, cyclists, and vehicles.
- Accommodation of mass transit, including all applicable bus, train, and ferry lines.
- Complete access by all authorized personnel to necessary utilities and to property.
- Protection of all work personnel and minimization of potential work hazards.
- Facilitation, to the extent possible, of fast and efficient project completion.
Much of the work involved in worksite traffic control involves clear, accurate communication with stakeholders at all levels. That includes ensuring that legal authorization is in place and that the public and property owners understand restrictions and responsibilities.
An overall traffic control strategy should embody these principles and practices:
- Clarity: Clear and positive guidance should be provided to road users before and during the traffic changes. A plan for public messaging about the changes should be in place weeks in advance and should remain in force throughout the project.
- Safety: Routine inspections of the worksite should proceed, day and night, so all issues can be documented and corrected. Roadside safety should remain a top priority, with all workers receiving adequate training to identify and correct problems.
- Structure: Traffic control should minimize restrictions on road movement to the lowest amount possible. Restrictions should go into place before work starts and should end as soon as they are no longer needed to ensure safety.
Considering the principles and practices above, it can’t be stressed enough the role of communication in traffic control. Advanced signing, not 500 feet but 2000 feet in advance gives the public time to comprehend the obstructions ahead. It is also very important that signs are promptly removed from sight when they no longer apply. When the public sees signs that do not apply, they easily begin to ignore all signs. Lane closures and speed signs are prime offenders of this. If a lane closure sign is left up, lane changing by drivers is common, which increases the chances for accidents.
The Basic Elements of Managing Work Zone Traffic
There are many resources available to safety experts when developing traffic control plans. Planners must be aware of the high-level environment created by applicable laws as well as the approaches that will be most effective considering the available personnel and materials.
These four basic elements should be analyzed as part of any traffic control strategy:
- Laws and Ordinances: Laws and ordinances are often far beyond the control of safety experts on the ground, but they must take regulations into account to ensure compliance standards are followed. Laws provide a top-level, strategic structure for safety design that serves as the outline for daily operational efforts.
- Traffic Control Devices: Traffic control devices include temporary moveable objects like cones and barricades. Items used must conform to the standards laid out by the Federal Highway Administration Manual on Uniform Traffic Devices, which specifies standard highway signs and markings, color specifications, and so on.
- Signs and Signals: Signs and signals provide guidance to road users on changes in traffic flow, timing of work, presence of workers, current and future route shutdowns, and other advisories. It is crucial that these devices be adequately maintained and that they provide clear, highly visible instructions to individuals on the road.
- Surveillance & Detection Devices: Surveillance devices such as roadside cameras and speed monitors have become increasingly common in worksite areas. These can be used to provide a deterrent against irresponsible road behavior in a traffic control zone. Their effectiveness depends on drivers’ awareness of their presence.
To ensure safety for all affected parties while facilitating a project, a civil engineer must be able to develop a dynamic, comprehensive traffic control plan from a large number of inputs. Each project will present different hazards to both motorists and workers. A thorough, end-to-end approach to safety benefits everyone and minimizes risk to life and property.