This research provided an opportunity to observe and analyze local small scale work zones. More specifically, 14 work zones were observed using surrogate measures of safety assessment as a means for identifying any safety-related hazards in the work zone. Existing conflict and event study procedures and worksheets as outlines in the background were adapted to allow for the spotting of issues in operating work zones (28).
To achieve the overall research task, the conflict and event studies were carried out in five steps which are presented in Figure 9.
FIGURE 9 Relationship between Task 4 and methodologic steps.
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3.4.1 Determination of Observations and Work Zones
The first of these steps was to determine what type of work zones would be observed and where and when they would occur as well as establish observation periods.
Initially, the work zones to be observed had to be identified. This was done through a series of methods including talking to MassDOT District 2 about construction locations, using websites including www.masstraveler.com which provides construction alerts along roadways in Massachusetts, the MassDOT Highway Division project webpage which lists current and past roadway construction projects searchable based on city location, calling local police departments and their detail offices, local Departments of Public Works, driving through areas of known construction and finally through speaking with on-duty detail officers and construction workers for suggestions as to where there would be construction in the upcoming weeks. A total of 14 work zones were observed over a period of two months, August and September. The work zones were selected based upon the ability to provide the opportunity for evaluation of a sample of several different types of work zone setups and therefore capture typical driver behavior in each of the work zones. A researcher observed every work zone, often with the help of an additional engineering student.
3.4.2 Initial Work Zone Observation
An initial observation was completed and using that observation, a method was developed to observe the 14 work zones. The researcher observed the work zone for an hour, taking notes of characteristics and events. In addition the detail officer was spoken with to determine his input on what types of characteristics are important to note for work
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zone safety. The first work zone is not included in the analyses because it was used as a base model for observing the work zones and developing the observation methodology.
3.4.3 Creation of Conflict and Event Study
Using the observations, a conflict and event study was created that could easily be performed in chosen work zones by several different observers with similar results. The conflict and event studies were developed to allow other researchers, professionals, and roadside workers to use them in the future to gather their own data or determine specific problem areas quickly and easily.
A worksheet was created for the observers to fill out as seen in Appendix D. The observers were asked to fill out information regarding many different aspects and characteristics of the work zone. These included: date, observer, time of day, weather, and location. They were next asked to comment on the work zone setup, including signs leading up to the work zone, type of lane closure, number of police and workers, and equipment. Observations were an hour wherever possible. Due to the mobile nature of many work zones and the difficulty of finding work zones, sometimes the work zones were unable to be observed for the entire hour-long period. The observers were also required to take pictures of the work zone and approaches.
During the observation period, , the observers were asked to keep a volume count, track of the type of work going on, the types of equipment being used, the numbers of workers and police, as well as any changes in the layout of the work zone. In certain work zones, speeds were recorded using a Lydar gun for vehicles entering, exiting,
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within, and not associated with the work zone. Due to the nature of many of the work zones, all speeds at all locations were not able to be recorded.
Finally, the observers were asked, for the entire period of observation, to record any conflicts or events they witness. The observers watched for evasive maneuvers like breaking or weaving that indicate a conflict which could potentially cause a crash. In addition, the observers were asked to describe in detail unusual actions or situations that are not typical for a normally behaving vehicle, like horn honking to determine what type of events are occurring and to facilitate the analysis process later. Events were categorized using traffic violations as well.
3.4.4 Performance of Conflict and Event Study
The 14 observations were completed in two months. The observers filled out a worksheet for each work zone and recorded all observed conflicts and events for each period. Pictures were also taken at each site. The observers asked to remain in an area that did not disturb either the construction workers or drivers to prevent influencing them and biasing the results of the study. A verification method was used, in the form of two people watching the work zone at once and comparing notes on conflicts and events, to ensure uniformity between multiple observers.
3.4.5 Analysis of Results
Once the 14 work zones were observed, the data was combined and analyzed to determine the factors and causes most commonly found in the observations for the different types of work zones. A thumbnail and description table was created for the
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work zones which were each given a unique ID number and the characteristics and recorded speeds were reported in the matrix form. The conflicts and events were divided into eight categories: traffic infractions, speed related, merge related, setup related, equipment related, age related, other, and serious conflicts and events.