Details:

Creators:
Uddin, Waheed
Corporate Creators:
University of Mississippi. Dept. of Civil Engineering
Corporate Contributors:
Mississippi. Dept. of Transportation. Research Division
Subject/TRT Terms:
[+]
Crash Data Crash Rates Highway Capacity Highway Research--Mississippi Roundabouts Traffic Congestion Traffic Delays Traffic Engineering Traffic Flow Traffic Safety Traffic Surveys Traffic Surveys--Mississippi
Publication/ Report Number:
FHWA/MS-DOT-RD-11-213 ; MS-DOT-RD-11-213
FHWA/MS-DOT-RD-11-213 ; MS-DOT-RD-11-213 Less -
Resource Type:
Tech Report
Geographical Coverage:
Mississippi
Edition:
Final report; June 30, 2011.
Corporate Publisher:
Mississippi. Dept. of Transportation
Abstract:
Due to increased traffic volume, congestion, and capacity limitations, two roundabouts have been constructed on South Lamar

Boulevard ramp intersections with MS Highway 6 in Oxford, MS. Roundabouts replaced the existing signalized intersection

on the north and stop controlled intersections on the south side of the South Lamar Boulevard and MS Highway 6 Interchange.

The overall objective of this study was to assess the performance of the roundabouts in Oxford with respect to traffic flow,

capacity, and safety improvements, and to determine the public perception of roundabouts by means of an opinion survey.

Detailed post-roundabout traffic movement volume and crash data were collected and compared with the pre-roundabout data

to assess the in-service performance of the roundabouts. Traffic flow microsimulation and capacity analysis methods were

used to evaluate performance of the roundabouts. The results of the Oxford roundabout study showed significant improvement

in traffic flow, crash reduction, and reduction in vehicle emissions. It was found that the conversion of the intersections to

roundabouts improved traffic flow by reducing average delay by 24%, idling time by 77%, and fuel wastage by 56%. Overall

vehicle emissions from idling were reduced significantly including 56% in CO2, 80% in VOC, and 77% in CO, NOx, and PM10.

This conversion of stop-controlled intersections to roundabouts increased the average speed by 67% and improved level of

service of both roundabouts. The roundabout conversion increased the mean speed on the South Lamar interchange by 67%

and improved level of service for both intersections. The roundabout junctions improved safety performance through a 37.5%

reduction in crashes and a 60% reduction in the number of crashes resulting in injury. The reduction in overall crashes in the

study area reduced comprehensive cost by 54.4%. Total user cost saving from reductions in travel time, fuel wastage, and

crash cost combined is $806,018 annually. These benefits paid off the total cost of construction of the two roundabouts within

two years. The resulting B/C ratio is 6.2 over a period from 2009 to 2016. Additionally, significant societal benefits are

expected from reductions in vehicle emissions. Also, an anonymous public opinion survey overwhelmingly demonstrated

favorable results and provides support to consider more roundabout junctions in place of stop-controlled intersections. The

study results indicate that roundabouts are performing well as intended. Some constructive comments suggested by the public,

such as flashing lights on signs, can be implemented by the Mississippi DOT to enhance traffic flow and safety.


Format:
PDF
Collection(s):
US Transportation Collection
Main Document Checksum:
[+]
urn:sha256:3fde1ea6feca7b55b16ad5b1bdeb634c5860a2565f83122cc2f75fbe839337a4
Download URL:
https://rosap.ntl.bts.gov/view/dot/24083/dot_24083_DS1.pdf
File Type:

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