Work Zone Mobility and Safety Program
Photo collage: temporary lane closure, road marking installation, cone with mounted warning light, and drum separated work zones.
Office of Operations 21st Century Operations Using 21st Century Technologies

Missouri DOT I-64 Rehabilitation Case Study

In March 2007, the Missouri Department of Transportation (MoDOT) began a two-and-a-half year project to rebuild the Interstate 64 corridor through St. Louis, Missouri. The project involved repairing or rebuilding 10 miles of roadway and 30 bridges along the corridor. To plan for this large-scale project, MoDOT performed a work zone impacts analysis to determine the best method for performing the work with minimal disruption and inconvenience to the surrounding community. The results of the impacts analysis led MoDOT to decide to fully close the road (with the western half of the project closed for one year, followed by a one year closure of the eastern half) and to bid the project as design-build. MoDOT challenged the contractor to use regional modeling to develop the transportation management plan (TMP) and project design, and gave the contractor joint responsibility for handling the public outreach for the project.

The closure was expected to bring the largest traffic disruption that St. Louis experienced in decades, and many, including the press, were doubtful that everything would go smoothly. However, MoDOT found that commutes during the closure went fairly smoothly, due to drivers adjusting their work hours and avoiding routes that were known to be problem spots, and due to MoDOT's ability to respond quickly to problem spots and incidents. An editorial in the St. Louis Post-Dispatch even apologized for assuming that the closure would lead to a disaster, admitting that, "…we were wrong about the Missouri Department of Transportation and Highway 40. The alternative routes devised by MoDOT and its experts have worked spectacularly well. Public works departments in St. Louis County and affected municipalities synchronized traffic lights brilliantly." (From the editorial, "Bigly Goatish", February 12, 2008, St. Louis Post-Dispatch). The project, originally anticipated to cost $535 million, finished $11 million under budget and several weeks ahead of schedule, with all lanes of I-64 reopening on December 7, 2009.

MoDOT considered the project to be a success, which can be attributed to the extensive planning and preparation for the project and the closure. The sequence of steps that MoDOT went through to prepare for the closure of I-64 exemplifies the goals of the Work Zone Safety and Mobility Rule. These steps are described below.

Impacts Assessment

In the early 1990s, MoDOT presented a preliminary design for the widening of I-64, but negative public response put the project on hold for a few years. In the mid-1990s, the East-West Gateway Council of Governments (EWGCOG) did a planning study on the I-64 corridor to look at roadway and transit needs. MoDOT was part of the study team. The study resulted in the recommendation to widen I-64 and this time the project was approved. To minimize impacts to the community and surrounding local businesses, MoDOT focused extensively on identifying and analyzing potential impacts, both before bidding the project to determine the best way to handle construction, and after bidding the project to determine how to plan accordingly once construction began. This extensive impacts assessment led to the decision to use a full closure with design-build contracting, and allowed this approach to be implemented successfully.

Impacts Assessment Prior to Bidding the Project

As part of the pre-work before bidding this project, MoDOT used regional modeling to predict how the traffic would act under different road closure scenarios. MoDOT used TransEval, EWCOG's regional travel demand management model, to analyze traffic for current conditions and for maintenance of traffic (MOT) options during construction. The modeling led MoDOT to make improvements to nearby arterial corridors before the project officially began to alleviate bottlenecks that already existed in the surrounding area. Improvements included coordinating signal timing and adding lanes to those alternate routes. MoDOT also did several value engineering studies on constructability in the corridor in an effort to use the existing right-of-way rather than purchasing more land from the surrounding community.

In planning for the project, MoDOT initially thought it would keep two lanes open in each direction, rebuilding one interchange per year. MoDOT estimated this to take 6-15 years and determined that this would not be acceptable to the community. Furthermore, the MoDOT Director had challenged his staff to complete the construction in four years. As a result, MoDOT began looking at the regional road network and realized that if they looked regionally, they had many more options for MOT that would enable completing the project in less time.

After assessing the impacts of different construction alternatives on the surrounding community, and factoring the need to finish the work within three years, MoDOT decided to do a full closure with a design-build contracting approach. The modeling done in the pre-planning stages indicated that the corridor would be able to handle a full closure.

The extensive impacts analysis that MoDOT performed prior to bidding the project allowed MoDOT to quickly evaluate the proposals that were received. MoDOT checked the contractors' plans and models against the various scenarios that had been modeled and analyzed during its own impacts analysis to ensure the selected contractor understood the traffic in the region and had presented a reasonable approach.

Impacts Assessment After Contract Award

The contractor selected for the work used TransEval software to predict traffic impacts from the full closure. They looked at four traffic data sets - trip generation, trip distribution, modal distribution, and trip assignment). The information gathered enabled MoDOT to predict when travel shifts were likely to occur and where traffic hot spots would exist throughout the construction phases.

Predicting the regional traffic impacts was also done qualitatively by looking at the results from St. Louis County's "I-64 TMP Task Force Committee Final Report," done in 2006, field reviews, and the downtown St. Louis Partnership's "St. Louis I-64 Reconstruction Project Findings" report, also from 2006.

Using all of this data, tables were developed to show:

  • Impacts during each year of construction on each of the major roads and bridge crossings at the Mississippi and Missouri Rivers
  • Excess capacity for each road so that detours could be planned
  • Impacts that the I-64 closure would have on transit.

Mitigation strategies to handle the impacts were developed for the region and documented in the TMP.

Transportation Management Plan Development

The I-64 TMP was developed with a multi-disciplinary team that included emergency service providers, local community members, MoDOT, the contractor team, and hospital personnel. By bringing these parties together from the start, MoDOT and the contractor were able to plan for contingencies and alleviate potential stumbling points before they became a problem.

The TMP included:

  • A plan for when and how the roads affected were going to close and be reopened throughout the project to ensure adequate access and mobility for road users, including emergency services. A three phase plan was developed for the construction. By splitting the project into phases, the contractor was able to maintain traffic flow while still completing the project at a faster rate than rolling road closures would have permitted.
  • Information on which bridges would close for repairs along I-64, when they would close, and what alternate routes would be available during the construction. The alternate routes were detailed in tables in the TMP to show the original route, the detour route, and if mitigation strategies would be used to inform the public about the changes (signage, ads, etc). Maps were developed for each route with the detours plotted to inform the public.
  • Use of a Transportation Management Center (TMC). An existing regional TMC was an integral part of the TMP. Transportation officials from St. Louis County, St. Louis, regional transit and the Missouri Highway Patrol formed a command center within the TMC to monitor real-time traffic conditions in the project area and along alternate routes to respond quickly to problems. By having all of the stakeholders in the same building, problems could be alleviated before major delays occurred.
  • An incident response plan that included emergency access maps for each stage of the project. The incident response plan was developed to help meet four incident management goals for the project: minimize clearance times, alert motorists to incidents ahead, provide clear access to emergency vehicles responding to the incident, and support response to incidents in the corridor. The regional TMC was an integral part of the incident response plan. The TMC had an incident support coordinator available 24/7 to manage incident response and clearance quickly (within 45 minutes of occurrence) and to do so with an awareness of the current construction conditions along the corridor. The TMC also enabled MoDOT to bring all of the officials necessary to make decisions during an incident into one room and decide on the best course of action together rather than independently.
  • An extensive public information plan that detailed the specific strategies to be used, key points of contact, target audiences for each strategy, the timeframe for completing each strategy, and how the effectiveness of each strategy would be measured, if applicable.

Public Information and Outreach Strategies

MoDOT recognized that in order to gain acceptance and support for the project, they would need to involve the public both before and during the project. Prior to beginning the project, MoDOT worked with the public and other partners through a five year environmental evaluation process to understand the needs of the public and to come to agreement on how to best meet the needs of the community and MoDOT. Working and sharing information with the surrounding community continued once the project began, including meeting with approximately 10,000 people in the surrounding community prior to the closure to help them prepare and cope.

Both MoDOT and the contractor handled the public outreach for the project. MoDOT was responsible for addressing big-picture items such as the overall progress towards meeting the project's goals, overall messages for the public, and outreach concerning regional traffic patterns. The contractor was responsible for the day-to-day communications with the public concerning short-term progress, construction schedules, and street closures. By sharing the responsibility for public outreach with the contractor, MoDOT was able to encourage the contractor to accept ownership of the project and understand first-hand the impacts that the project had on the surrounding community and the importance of managing those impacts.

In addition to sharing information with the public about the project through a project hotline, community events, and press releases, other public outreach strategies used during the project included:

  • Project web site - The project web site ( was used to share current information about the project, alternate routes, traffic conditions, project photos, and live web-cams showing construction as it occurred. Throughout the project, MoDOT and the contractor hosted a weekly online chat forum through the web site.
  • News conferences - At the beginning of the project, MoDOT held daily press conferences to update the public on the day's progress and tell them about alternate routes and build he community's trust with MoDOT.
  • Surveys - Surveys were heavily used on the project to gauge the public's reaction to the closure. An online survey was designed specifically for this project and was available through the project web site. The online survey received an average of 40-50 responses a month. The other means of gathering information was through two questions added to the motorist assist surveys distributed by MoDOT operators after providing traffic assistance to motorists in need. After receiving assistance, motorists were asked a few questions about their experience with the program and their experience driving through the corridor. Surveys were also handed out at public events and sent to local businesses and hospitals along the corridor, although the return rate for these surveys was much lower than the online and motorist assist surveys. Responses indicated high overall satisfaction with the project and that the public wanted the traffic monitoring and incident coordination activities to continue after the construction along I-64 was completed. The responses also indicated that TV news, Internet, radio news, and roadway signs were the leading ways that the public obtained information about the project.

TMP Monitoring

MoDOT recognized that the TMP is a "living document" and assigned a group to monitor the TMP during the project and adjust it as necessary. However, after the first few weeks the group found that no significant adjustments were needed once the surrounding community became familiar with the construction and associated detours. In addition to monitoring the TMP, a task force was formed to monitor the project as a whole. This task force met twice a month to discuss the project, its progress, any concerns that had arisen during the time period before the meeting, and to coordinate public information releases and coordinate/communicate with emergency response personnel.

Collection and Analysis of Performance Data

MoDOT performed extensive data collection and analysis efforts to measure performance of the work zone and public satisfaction with the project. In addition to collecting data through numerous sources, MoDOT hired a consultant to collect and analyze data from this project regarding traffic flow, economic impacts and how the public handled the changes to traffic during construction. The consultant produced quarterly reports analyzing this data.

The types of data collected included:

  • Economic data - MoDOT worked with the Department of Economic development to collect and analyze this data to help quantify the impacts of the project on the surrounding community. Data included sales tax income and real estate prices before, during, and after the project to see how the project affected businesses and the sale of homes near the corridor. National trends were analyzed to determine if any changes were the result of the project or could be tied to national trends. MoDOT also partnered with local and regional economic development organizations to distribute surveys to businesses. The surveys focused on the effects of the project on commuting, transportation/shipping costs, and visitation.
  • Mobility data - MoDOT used traffic counts, travel-time runs along alternate routes, park-and-ride facility count data, transit ridership data, rideshare data, and field observations to analyze mobility in the project area during construction. MoDOT also partnered with to obtain archived traffic volume, travel speed, and incident data in 1-minute intervals for the corridor.
  • Crash data - MoDOT obtained crash data from local police departments to analyze the safety impacts of the project, comparing statistics from before the work started with after the closure was in place.
  • Public satisfaction data - MoDOT collected information on the public's satisfaction with the project through an online survey and surveys handed out at local events. As mentioned in the Public Outreach section, they also collected public satisfaction data by adding two questions about the project to motorist assist questionnaires distributed by MoDOT operators after providing traffic assistance to motorists in need.

Lessons Learned

MoDOT considered this project be a success and identified a number of success factors that can be applied to other projects, including:

  • Think regionally - Regional needs should be identified and incorporated early in the planning process of major construction projects to be able to implement and deploy strategies that can be either permanent (long-term value) or temporary (short-term value) to enhance mobility and reduce potential impacts, not only in the project corridor, but on surrounding regional routes. During construction, working with the local TMC is important to understanding and addressing issues with the traffic flow on arterials and freeways.
  • Develop and maintain partnerships - Stakeholders from the community, local agencies, and other interested parties should coordinate with the transportation department and contractor and be involved as much as possible.
  • Do a cost/benefit analysis - Just because you can close the road doesn't mean that you should do it. It is useful to do a cost/benefit analysis before deciding to use the full closure approach to ensure the approach will bring cost savings, safety improvements for workers and motorists, and a shorter project timeline.
  • Asses impacts prior to beginning the project - Thoroughly assessing and planning for impacts prior to beginning a project may help:
    • Address any improvements to potential alternate routes that are needed before construction
    • Identify the best construction strategy for the project
    • Increase understanding of MOT options that could potentially shorten project duration
    • Ensure that the TMP contains appropriate strategies for mitigating impacts during the project.
  • Develop a well-defined, flexible TMP - Share the TMP with stakeholders and the community before construction to ensure it meets their needs and adjust the TMP as needed during construction.
  • Implement effective public information and outreach - Inform the public about the project and ways to mitigate impacts every step of the way. In addition, provide as much traffic information as possible, both from the transportation department and private sources, to inform travelers pre-trip and en-route.