Reduced Traffic Speed in Work Zones

White Paper
Reduced Traffic Speed in Work Zones
By Calvin Lee, ICA

Purpose
The purpose of this paper is to provide an overview of the worksite speed limit process, identify the methods by which INDOT establishes work zone and worksite speed limits and to summarize the procedure contractors can follow to request worksite speed limit reductions when the need was not identified during the design process.

Introduction
As our highway infrastructure ages, INDOT is focusing on rebuilding existing roadways instead of building new ones. Highway improvement projects are increasing on roadways that are open to traffic. At the same time, growing traffic volumes, and increased speeds through work zones have created additional concerns and challenges to protect highway workers. This combination of more work zones and heavier traffic, if not managed, can lead to a substantial increase of worker exposure thus resulting in a greater potential for worker injuries and fatalities.

Every year in our nation, thousands of persons are either injured or killed in work zones. In fact, at least three people die every day and every nine minutes someone is injured in work zone related crashes. In Indiana, seven (7) people were killed and 835 were injured in work zones in 2007. Speed is a major contributor to the mishaps that occur in work zones. It is a proven fact that speeding increases risk, therefore causing an increased number of injuries and fatalities in work zones. Although four out of every five work zone crashes involved only the motoring public, it is imperative that every effort be made to protect highway workers performing their duties on the roadway.

While speed limits are set by state law, INDOT and local agencies have the authority to adjust speed limits “on the basis of an engineering study and traffic investigation.” The law also gives INDOT and local agencies the authority to establish temporary speed limits in the vicinity of a worksite without such an engineering study and investigation.

Overview
Reduce driving speeds in work zones. This is a lot easier said than done. There are many factors that go into making this a reality.

Over the years there have been many strategies introduced to make work zones safer. Some seemed to be quite promising, some appeared to be too cumbersome and more of a challenge to use and others were simply ineffective. However, when it comes to reducing speeds in work zones, most agree that the use of law enforcement officers in work zones is the most effective and preferred method. Drivers have a tendency to respond in an appropriate manner when an officer is present in the work zone; especially in those situations when it is clear that citations are being issued. Most are also aware that, because of economic considerations and budgetary constraints, there are limited amounts of funding available for this program. Therefore, officers cannot be made available for every jobsite. Up to this point, the procedures used to determine where and when officers will be deployed to a particular jobsite have been somewhat indistinct. However, INDOT is currently working on a procedure to help determine the most appropriate locations for speed patrols in work zones. Outside of this program, contractors can work with local police agencies to help provide assistance in work zones but no funding is available for their services.

Speed limits in work zones have been a concern for quite some time along with workers being exposed to such traffic. In 1991, the INDOT Commissioner received the authority to reduce speed limits at the worksite without an official action (OA). What is important to know about this accomplishment is that an OA was very difficult to achieve and it took quite an amount of time to develop. The establishment of reduced worksite speed limits means that, where appropriate, speed limits through worksites would never exceed 45mph. The reason for this is the statute states that “the worksite speeds would be set at 10mph below the posted speed limit or 45mph, whichever is lower.” One of the common misconceptions or misunderstandings with this language is that it applies to work zone speed limits and that the term worksite is used interchangeably with work zone, when in fact they are very different. The difference is, the work zone comprises the entire length of the job. The worksite involves only the area where the work is in progress. Therefore, in those cases that warrant a reduction in speed at the worksite from the posted speed in the work zone, the “Temporary Worksite Speed Limit Assembly Signs” will be used to reduce the speed of traffic at the worksite. These reduced speeds will only be applicable when workers are present. The yellow flashing lights that are affixed to the sign are there to indicate such (see INDOT Operations Memorandum 06-01 dated August 15, 2006 for specifics on signs, including proper placement). INDOT also requires the use of “Worksite Speed Limit Assembly Signs” to be recorded on an approved form (see recurring special provision 801-T-166 that will be included in construction contracts beginning in July 2008).

Process
Work zone and worksite speed limits are in most cases predetermined during the construction design process. Many factors go into determining the most appropriate speed limits for the conditions, including the construction zone design speed, traffic volumes, type of work planned, geometrics and the length of the project (see Part 8 of the INDOT Design Manual for specific factors). Suggested changes and discrepancies should be dealt with in the same manner as other jobsite issues. An example of a reason to request changes could include an instance where worksite speed reductions are not built into the project in specific locations and once the work commences the contractor believes that the speeds should be reduced at the worksite; this could be because of hazards created by 1) construction vehicles needing to enter and exit the worksite from the roadway, which could result in an accident; 2) workers needing to work in closer proximity to traffic, than originally planned; or 3) the contour of the roadway is such that errant vehicles could easily enter the work area i.e. on a curve or incline.

The use of Temporary Worksite Speed Limit Assembly Signs (TWSL) shall be used in accordance with the INDOT departmental policy identified in the INDOT Operations Memorandum 06-01 dated August 15, 2006. This document was published as an attachment to Construction Memorandum 06-22 dated August 23, 2006. When using TWSLs it is important to place the signs adjacent to existing speed limit signs or cover the existing signs. Otherwise, the lower posted speeds are only applicable until the driver reaches signs with higher posted speeds.

Conclusion
The information in this paper has been compiled to allow the reader to gain the basic knowledge of the worksite speed limit process. It explains that work zone and worksite predetermined speed limits are data-driven decisions, and that the goal of making work zones safe for highway workers is a shared desire. Most safety professionals and others within the highway construction industry are very focused on identifying methods by which workers receive the maximum amount of protection in work zones. Work zone safety strategies must and do involve both safety and mobility considerations. The contrast of safety and mobility seems to parallel the safety versus production scenario. Both must be viewed and acted upon equally and with the same level of importance. The MUTCD cautions construction work zone designers against reducing speeds in work zones too drastically from the normal posted speed for a particular road. It also stresses that requiring motorists to frequently change speeds while traveling through a work zone can be detrimental.

Although police presence in work zones is the most desired method to reduce speeds in work zones, it is important to consider other alternatives. When reviewing past reports on work zone and worksite fatalities, it becomes apparent that some attention must be given to mishaps that occur within the barrier walls as well. Emphasis must continue to be placed on high-visibility apparel, positive separation of workers from traffic, the use of special devices i.e. rumble strips, changeable message signs, intrusion alarms etc., worker training, safety planning and activity area arrangement to ensure that routes within the work area are identified and clearly marked to allow workers and worksite vehicular traffic to safely occupy the work space, overhead and underground utilities are clearly marked, and much more. Efforts to make work zones safe for workers and the public must continue to be a work in progress.

References:
FHWA Website http://www.fhwa.dot.gov/index.html
INDOT Website http://www.in.gov/indot/7316.htm
INDOT Memorandum from Christine Letts Dated May 24, 1991
INDOT Construction Memorandum 06-22 Dated August 23, 2006
INDOT Operations Memorandum 06-01 Dated August 15, 2006
INDOT Design Manual
MUTCD 2003
IC 9-21-5-11
IC 9-13-2-200
Construction Contract Special provision 801-T-166


Article A – “801-T-166 Temporary Worksite Speed Limit Reporting”
Article B – “IC 9-21-5, Chapter 5. Speed Limits”
Article C – “Construction Memorandum dated August 23, 2006”