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Project Details
STATUS

Completed

START DATE

08/08/14

END DATE

08/08/14

RESEARCH CENTERS InTrans, SWZDI
SPONSORS

Missouri

Researchers
Principal Investigator
Carlos Sun
Co-Principal Investigator
Praveen Edara

University of Missouri-Columbia

Co-Principal Investigator
Henry Brown

University of Missouri - Columbia

Student Researcher(s)
Zhongyuan (Eric) Zhu
Roozbeh Rahmani

About the research

The Highway Safety Manual is the national safety manual that provides quantitative methods for analyzing highway safety. The HSM presents crash modification factors related to work zone characteristics such as work zone duration and length. These crash modification factors were based on high-impact work zones in California. Therefore there was a need to use work zone and safety data from the Midwest to calibrate these crash modification factors for use in the Midwest. Almost 11,000 Missouri freeway work zones were analyzed to derive a representative and stratified sample of 162 work zones. The 162 work zones was more than four times the number of work zones used in the HSM. This dataset was used for modeling and testing crash modification factors applicable to the Midwest. The dataset contained work zones ranging from 0.76 mile to 9.24 miles and with durations from 16 days to 590 days. A combined fatal/injury/non-injury model produced a R2 fit of 0.9079 and a prediction slope of 0.963. The resulting crash modification factors of 1.01 for duration and 0.58 for length were smaller than the values in the HSM. Two practical application examples illustrate the use of the crash modification factors for comparing alternate work zone setups.

Project Details
STATUS

Completed

START DATE

08/08/15

END DATE

08/08/15

RESEARCH CENTERS InTrans, SWZDI
SPONSORS

Missouri

Researchers
Principal Investigator
Henry Brown

University of Missouri - Columbia

Co-Principal Investigator
Carlos Sun
Co-Principal Investigator
Praveen Edara

University of Missouri-Columbia

Student Researcher(s)
Timothy Cope
AmirHossein Khezerzadeh

About the research

Currently there are no guidelines within the Manual on Uniform Traffic Control Devices (MUTCD) on construction phasing and maintenance of traffic (MOT) for retrofit construction and maintenance projects involving innovative geometric designs. The research presented in this report addressed this gap in existing knowledge by investigating the state of the practice of construction phasing and MOT for several types of innovative geometric designs including the roundabout, single point urban interchange (SPUI), diverging diamond interchange (DDI), restricted-crossing left turn (RCUT), median U-turn (MUT), and displaced left turn (DLT). This report provides guidelines for transportation practitioners in developing construction phasing and MOT plans for innovative geometric designs. This report includes MOT Phasing Diagrams to assist in the development of MOT strategies for innovative designs. The MOT Phasing Diagrams were developed through a review of literature, survey, interviews with practitioners, and review of plans from innovative geometric design projects. These diagrams are provided as a tool to assist in improving work zone safety and mobility through construction of projects with innovative geometric designs. The aforementioned synthesis of existing knowledge documented existing practices for these types of designs.

Project Details
STATUS

Completed

START DATE

08/08/11

END DATE

08/08/11

RESEARCH CENTERS InTrans, SWZDI
SPONSORS

Missouri

Researchers
Principal Investigator
Ghulam Bham

University of Missouri, Rolla

Student Researcher(s)
Mojtaba Ale Mohammadi

About the research

This study objectively and subjectively examined speed characteristics and driver compliance with the posted speed limit in Missouri work zones. The objective evaluation collected vehicle speeds from four work zones with different configurations on I-44. The effects of lane closure, lane width reduction, and construction activity on speeds of cars and trucks were evaluated. Construction activity was found to have a statistically significant effect in reducing vehicle speeds. During no construction, passenger cars and trucks speeds were 3.5 and 2.2 mph higher than their speeds during periods of construction activity, respectively. The vehicle speeds were found to be statistically higher than the posted speed limit in all cases studied except when the lane width was reduced using tubular markers, which reduced the speed of cars and trucks by 8.5 and 11.1 mph for cars and trucks during construction activity, respectively. This figure was respectively 4.0 and 8.1 mph during no construction. Also, compliance with speed limits was lower for posted speed limits of 50 mph versus 60 mph. Two subjective evaluations were conducted: first, work zone speed limit practiced at state departments of transportations were surveyed, and second, drivers’ perceptions of driving through the work zones were investigated. Specific questions that evaluated driver perception were related to compliance with the posted speed limit, safety, and the effects of various factors on their speed. Results of subjective evaluation were consistent with the objective evaluation and showed that drivers suggest a work zone speed limit consistent with the speed that they drove through the work zone. When a work zone was mostly congested, 92% of car drivers and all of the truck drivers suggested a reduction in speed limits. Conversely, 92% of car drivers and 73% of truck drivers suggested a higher posted speed limit when the work zone was not congested. More than 90% of drivers agreed that construction

Project Details
STATUS

Completed

START DATE

08/08/11

END DATE

08/08/11

RESEARCH CENTERS InTrans, SWZDI
SPONSORS

Missouri

Researchers
Principal Investigator
Ghulam Bham

University of Missouri, Rolla

Student Researcher(s)
S. Heidi Khazraee

About the research

Several days of traffic data were recorded at a long-term work zone near Pacific MO in both eastbound and westbound directions. A total of 11 breakdown events were identified using average speed profiles. The traffic flows prior to and after the onset of congestion were studied. For this work zone site, breakdown flow rates ranged between 1194 to 1404 vphpl, with an average of 1295 vphpl, while the mean queue discharge rate was equal to 1072 vphpl. The difference between mean breakdown and queue-discharge flow rates is due to the fact that flow usually drops once traffic breaks down and queues start to form. It is suggested that breakdown flow definition should be used in estimation of capacity if congestion is to be avoided, whereas mean queue discharge definition should be used if delays are to be estimated. Most of the breakdown flow rates found in this study exceeded the maximum capacity value used by Missouri DOT for prevention of congestion i.e., 1240 vphpl. The capacity value defined in terms of mean queue discharge as used by HCM 2000 was 1199 pcphpl, which is well below the HCM’s average capacity of 1600 pcphpl. This reduction in capacity is attributed mainly to reduced lane width. Additionally, it can be attributed to higher percentage of heavy vehicles, around 25% in the traffic stream.

Project Details
STATUS

Completed

START DATE

08/08/11

END DATE

08/08/11

RESEARCH CENTERS InTrans, SWZDI
SPONSORS

Missouri

Researchers
Principal Investigator
Ghulam Bham

University of Missouri, Rolla

Co-Principal Investigator
Ming Leu

Missouri University of Science and Technology

Co-Principal Investigator
Durga Raj Mathur

Missouri University of Science and Technology

Co-Principal Investigator
Manoj Vallati

Missouri University of Science and Technology

About the research

This project presents a study of driver perceptions using a driving simulator. The evaluation required one hundred and twenty participants from different age groups to drive through virtual highway work zones. During this experiment, driver reaction to VMA markings was determined based on their lane change distance. The drivers were also surveyed using a detailed subjective survey. Analysis of variance was performed to determine the significant variables affecting the lane change distance. For each time of day, a test was conducted to calculate the difference in lane change distance between the markings. A Kolmogorov-Smirnov test was carried out to evaluate the significance of differences between the lane change distance frequency distributions of the markings. For the subjective evaluation, the markings were ranked by participants indicating their preferences using four different criteria for each time of day. Additionally, the participants were surveyed on the features of the individual markings and for the most preferred marking. The results of the objective and subjective evaluations indicated that, overall, the red and white checkerboard pattern was most effective.

Project Details
STATUS

Completed

START DATE

08/08/14

END DATE

08/08/14

RESEARCH CENTERS InTrans, SWZDI
SPONSORS

Missouri

Researchers
Principal Investigator
Ghulam Bham

University of Missouri, Rolla

Co-Principal Investigator
Ming Leu

Missouri University of Science and Technology

Student Researcher(s)
Bharat K. Venkat
Mojtaba Ale Mohammadi

About the research

This report analyzed the effects of portable changeable message signs (PCMS) on driver behavior in terms of speed characteristics using a driving simulator. Fifty-two participants from different age groups evaluated four messaging signs with text and number by driving through a virtual work zone. Driver reactions to the message signs were analyzed by examining drivers’ speed before and after each PCMS. It was observed that speeds did not vary significantly for the first seven intervals (defined before and after each PCMS). Significant difference, however, was found on the eighth interval before the start of the lane closure. A 70 mph highway served as the control scenario on which the mean speed of drivers was observed to be 62.55 mph. For the first message sign (MS-1) (Caution Work Zone Ahead: Reduce Speed Ahead) the mean speed of drivers decreased by 9.35 mph compared to the control scenario. For MS-2 (Speed Ahead 30 mph; 2 min to end of WZ), the mean speed reduced by 36.06 mph compared to the control scenario. For MS-3 (Prepare to stop; 4 min to end of WZ) a decrease of 39.46 mph was observed. For MS-4 (Prepare to stop; Stopped traffic ahead) a decrease of 48.91 mph was observed compared to the control scenario. Therefore, MS-4 showed the highest speed reduction compared to other messages. A participant survey was conducted to examine the drivers’ rating of the message signs. From this subjective evaluation, MS-2 was rated as the most effective as it was specific in terms of the anticipated speed ahead indicated and hence easier for drivers to follow.

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