TRANSPORTATION RESEARCH

The Howard University Transportation Research Center (HUTRC) was established in the Civil Engineering Department to lead interdisciplinary urban transportation research in Washington, DC. The Center seeks to support the interest of the University and its sponsors. In addition to direct involvement in research projects, the key staff members of HUTRC are also engaged in the management of diverse studies and building alliances with other research entities.

Over the past 20 years, HUTRC has embarked upon research, training and outreach activities in areas such as transportation policy, management, planning, economics, engineering and policy.

The following are some of the peer reviewed papers and reports that have been published:

  1. Exploring Strategies to Improve Mobility and Safety on Roadway Segments in Urban Areas

  2. Development of Bus-Stop Time Models in Dense Urban Areas: A Case Study in Washington DC

  3. Optimization of Transit Total Bus Stop Time Models

  4. Predicting Pavement Condition Index Using International Roughness Index in a Dense Urban Area

  5. Optimal Mix Design for Pervious Concrete for an Urban Area

  6. Acceptable International Roughness Index Thresholds based on Present Serviceability Rating

  7. Evaluation of Bus Transit Reliability in the District of Columbia

  8. Establishing International Roughness Indices (IRI) for a dense urban area

Optimization of Transit Total Bus Stop Time Models

 

The reliability on bus transit systems depends on several factors including the route of travel, traffic conditions, time of day and dwell time (DT). Dwell time (DT) is defined as the time that a transit vehicle stops for the purpose of serving passengers. It includes the total passenger service time between the opening and closing of doors. The DT at bus stops represents a significant portion of route operating time, and its variability is linked to the reliability of the service being provided. A new variable, Total Bus Stop Time (TBST), was defined to help with the improvement of transit bus schedule compliance. It is defined as the sum of the DT and the time it takes a bus to safely maneuver into a bus stop and then re-entering to the main traffic stream. The motivation of these papers is to minimize both TBST and DT in order to improve overall reliability of transit buses.

 

In these papers, the inclusion of secondary factors played an important role in developing the prediction and optimization models. Papers #4 and #7 presented statistically significant DT and TBST models which were optimization by time of the day and by bus stop location. The local transit agency, Washington Metropolitan Transit Authority (WMATA), is considering adopting the models and using them for schedule planning and updating purposes. Minimizing TBST at bus stops will improve published route schedules and increase the accuracy of travel time variation along bus routes.

PROJECT DETAILS

 

Project Dates: 

2014 - 2015

Principal Investigators: 

Dr.Stephen Arhin

Dr. Errol C. Noel

Institution: 

Howard University

Publications: 

Journal of Traffic and Transportation Engineering

Volume 3, Issue 2, April 2016

Pages 146–153

Project Status: 

Complete

           

Predicting Pavement Condition Index (PCI) Using International Roughness Index (IRI) in a Dense Urban Area

 

The literature suggests that distresses in pavement surface, Pavement Condition Index, (PCI) influence the smoothness (IRI) of a pavement. IRI is a computer-generated measure of the smoothness of roadway segments while PCI is a subjective evaluation of the distress on a pavement section. As a result, in order to eliminate the subjectivity in determining PCI, some jurisdictions have modeled relationships between IRI and PCI with the aim of predicting PCI from the IRI. The data driven approach to quantifying IRI threshold can significantly affect roadway improvement investments. The motivation to reduce cost and labor hours while eliminating the subjectivity of determining the PCI is the motivation for this research. This resulted in the development of a model that predicts PCI from IRI for all roadway classifications at a 95% confidence level. The models were subsequently validated using 5-year IRI-PCI datasets. The study helped to reduce the time for collecting, reviewing, and processing distress photographs and subjectively rating the pavement conditions to obtain PCI. This has gained national value since other jurisdictions have followed suit in developing models involving pavement indices.

 

 

PROJECT DETAILS

 

Project Dates: 

2013 - 2014

Principal Investigators: 

Dr. Stephen A. Arhin

Melissa F. Anderson

Asteway Ribbiso

Lakeasha N. Williams

Institution: 

HUTRC

Sponsor(s): 

DDOT

Publications: 

         Journal of Civil Engineering Research

         Volume 5, Issue 1 2015

         Pages 10-17

Project Status: 

Complete

 

 
 

Optimal Mix Design for Pervious Concrete in an Urban Area

 

Pervious concrete (also called porous concrete, permeable concrete and porous pavement) is a special type of concrete with a high porosity used for concrete flatwork applications that allows water from precipitation and other sources to pass directly through, thereby reducing the runoff from a site and allowing groundwater recharge. Pervious concrete is made using large aggregates with little to no fine aggregates. The concrete paste then coats the aggregates and allows water to pass through the concrete slab. Pervious concrete is traditionally used in parking areas, areas with light traffic, residential streets, pedestrian walkways, and greenhouses. It is an important application for sustainable construction and is one of many low impact development techniques used by builders to protect water quality. Due to geographical location, application and jurisdictional preferences, mix designs for pervious concrete may vary. There is no unified standard in place on the optimal mix design of pervious concrete pavements. This research was aimed at developing the optimal mix design of pervious concrete for the District of Columbia which was motivated as part of the District Green Ally project. This project involved the conversion of impervious alley pavements to pervious concrete to curb storm-water runoff.

 

 

 

PROJECT DETAILS

 

Project Dates: 

2013

Principal Investigators: 

Dr. Stephen Arhin

Dr. Rezene Madhi

Mr. Wasi Khan

Institution: 

HUTRC - DDOT

Sponsor(s): 

DDOT

Publications: 

International Journal of Engineering Research & Technology

Volume 3, Issue 12  2014

Project Status: 

Complete

 

Acceptable International Roughness Index Thresholds based on Present Serviceability Rating

 

The International Roughness Index (IRI) is one of the required performance measures that need to be reported to the Federal Highway Administration (FHWA) as part of the Highway Performance Monitoring System (HPMS) by all state agencies in the United States. The reported IRIs for road segments are compared to the national standards set by the FHWA.  Variations from the national standards are used to identify road segments that need to be included in repair or maintenance programs. According to the FHWA, road segments with IRI of 170 in/mi or less are deemed as “acceptable” while those with IRI of 95 in/mi or less are categorized as “good”. The sole use of the IRI for identifying repair and rehabilitation sections of highways has been under review in several states.  There is concern that the FHWA threshold values of the IRI are often in conflict with the ride perceived by the average citizen. This research paper presents the study which compiled the perception or rating of road smoothness by DC residents on the basis of which models were developed to determine the IRI thresholds applicable to the City. FHWA has since adopted the IRI thresholds for the District of Columbia based on this research. This has also changed the process by which the District of Columbia allocates funds for pavement rehabilitation. Most states have since established IRI thresholds based on the ride quality perceptions of their residents.

 

 

PROJECT DETAILS

 

Project Dates: 

2013

Principal Investigators: 

Dr. Stephen A. Arhin

Dr. Errol C. Noel

Mr. Asteway Ribbiso

Institution: 

HUTRC

Sponsor(s): 

DDOT

Publications: 

         Journal of Civil Engineering Research

         Volume 5, Issue 4  2015

         Pages 90-96

Project Status: 

Complete

 

Evaluation of Bus Transit Reliability in the District of Columbia

 

Several performance metrics can be used to assess the reliability of a transit system. These include on-time arrivals, travel-time adherence, run-time adherence, and customer satisfaction, among others. On-time arrival at bus stops is one of the performance metrics of the Washington Metropolitan Transit Authority (WMATA). A bus is considered to be on time by WMATA if it arrives at most two minutes earlier or seven minutes later than the scheduled arrival times, with a performance goal of 78%. Most regional transit agencies consider arrivals that fall within one minute earlier or five minutes later than the scheduled arrival times as being on time. The goal of this project was to determine the on-time performance and their statistical significance based on WMATA’s advertised threshold and the industry standard for on-time arrivals. Fifteen bus routes in Washington DC with several stops were studied in this research. WMATA’s published bus schedules provided expected arrival times. An on-board manual survey was conducted from June 2012 through June 2013 for peak morning and afternoon travel on those routes during which the actual arrival times at the bus stops were noted and compared with the scheduled arrival times. For WMATA’s two-minutes-early and seven-minutes-late arrival threshold, the buses were found to be on time approximately 82% of the time, on average, during the morning. In the evening, for the same threshold, only 68% of the buses on average were considered to be on time. This results in an overall on-time performance of 75%, which is a modest improvement over the 2010 on-time performance of 74%. Based on the one-minute early and five-minutes-late arrival threshold used by several regional transit agencies, the buses were found to be on time approximately 67% of the time during the morning and 55% in the evening, resulting in an overall performance of 61%.

 

 

PROJECT DETAILS

 

Project Dates: 

2012 - 2013

Principal Investigators: 

Dr. Stephen Arhin

Dr. Errol Noel

Institution: 

HUTRC - Mineta National Transit Research Consortium

Sponsor(s): 

DDOT

Publications: 

MNTRC Report 12-14

Project Status: 

Complete

 

Establishing International Roughness Indices (IRI) for a dense urban area

 

Pavement roughness is a characteristic which may be measured by various automatic multifunctional pavement measuring instruments or devices, and which may be expressed using the International Roughness Index (IRI), an international parameter used to measure pavement roughness conditions. Since 1990, the Federal Highway Administration (FHWA) has required states to report road roughness on the IRI scale for inclusion in the Highway Performance Monitoring System (HPMS).  This mandatory report has caused most states to take a second look at the FHWA adopted national IRI standards, which may or may not truly reflect actual perception of roughness or smoothness in the local jurisdiction.

 

This research established, as a minimum, benchmarks for relating motorists’ perception of ride quality in the District to IRI values obtained from automation. A relationship (regression models) between subjective (motorists’ perspective) and objective ride quality data (IRI) was established which enabled DDOT to assess the smoothness perception level of motorists based on IRI values (and vice versa). The regression models were established on a basis of 5% level of significance.

 

 

PROJECT DETAILS

 

Project Dates: 

2010

Principal Investigators: 

Dr. Stephen A. Arhin

Dr. Errol C. Noel

M. Lakew

Institution: 

HUTRC-DDOT

Sponsor(s): 

DDOT

Publications: 

WIT Transactions on Ecology and the Environment

Volume 129, 2010

Pages 275 - 286

Project Status: 

Complete

 

Evaluation of Sports Team Logo on Guide Signs in DC

 

Logos are generally not allowed to be placed on guide signs on freeways. However, in some instances, exceptions are granted based on experiments to provide the basis for its use, especially in dense urban areas, when signage may be confusing. This research was an effort aimed at conducting an experiment in accordance with the MUTCD.

 

In compliance with Section 1A.10 of the Manual on Uniform Traffic Control Devices, the sports team (Washington Nationals Baseball) logo on guide signs on freeways were tested and evaluated through the conduct of a survey for the purpose of its application or manner of use. The results showed that a significant percentage of the patrons (baseball fans) found the existing signage to be effective in guiding them to the stadium and preferred signage which included a logo and word on guide signs. Similarly, the non-patrons also recommended signage which included a logo and word message. Statistical inferences were conducted at 5% level of significance. The Federal Highway Administration is in the process of granting the District of Columbia an exception for the use of the sports logo on guide signs.

 

 

 

PROJECT DETAILS

 

Project Dates: 

2008

Principal Investigators: 

Dr. Stephen Arhin

Dr. Errol C. Noel

Institution: 

HUTRC - DDOT

Sponsor(s): 

DDOT

Publications: 

DDOT Report

Project Status: 

Complete

 

Partial List of Projects

  • Effectiveness and Acceptance of Adaptive Intelligent Speed Adaptation Systems2011 - 2008

  • Development and Evaluation of an Advanced Intelligent Speed Adaptation (ISA) System -2008

  • Evaluation of Countdown Pedestrian Signals in the District of Columbia- 2011

  • Preferred Countdown Pedestrian Signal Displays for Safety – 2011

  • Evaluation of Saw-Cut Sealants for the Prevention of Reflective Cracking in Hot Mix Asphalt - 2012

  • Long-Term Trends in Patron Satisfaction of the DC Circulator - 2013

  • Exploratory Compliance Rate for HAWK Signals in Dense Urban Areas: Case Study in Washington DC -2013

  • Bus On-Time Arrival Performance and Criteria in a Dense Urban Area - 2014

  • Optimal Mix Design for Pervious Concrete for an Urban Area - 2014

  • Acceptable International Roughness Index Thresholds based on Present Serviceability Rating - 2015

  • Prioritization of TCO Deployment in DC-2015

  • Predicting Driver Braking and Stopping Behavior using an Intelligent Speed Adaptation System - 2015

 

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