U.S. Department of Transportation
Federal Highway Administration
1200 New Jersey Avenue, SE
Washington, DC 20590
202-366-4000
This section presents qualitative evaluations of two RSIP projects:
Agency: Tennessee Department of Transportation (TDOT)
Focus of Evaluation: Development of Sign Inventory System
County governments in Tennessee expressed interest in meeting the retroreflectivity standards in the Manual on Uniform Traffic Control Devices (MUTCD; FHWA, 2009). Recognizing that better sign retroreflectivity increases safety, especially at night (motorists are more likely to notice and follow brighter, more visible signs), the counties were interested in decreasing crashes through the low-cost, system-wide implementation of more retroreflective signs. The counties sought to develop a project that included the creation of a sign inventory and retroreflectivity measurements for signs in the inventory. This would provide the necessary information for a data-driven sign replacement program. In addition, in 2007 FHWA published a final rule stating that public agencies with jurisdiction over roadways should have an assessment method for determining sign retroreflectivity and maintaining it above minimum standards. The 2009 MUTCD provides guidance for being compliant with this rule.
Through the RSIP project, Tennessee Department of Transportation (TDOT) implemented a pilot program for the development of a sign inventory system that focused on rural state routes in the 21 counties in the Delta region (TDOT's Region 4). TDOT partnered with a consulting firm and a manufacturer of sign sheeting to develop the sign inventory and process for conducting retroreflectivity and other sign quality measurements.
The goal of the project was to evaluate all the signing on state routes in the Delta region, develop an inventory system, record retroreflectivity measurements and general condition of the signs, assign a latitude and longitude (i.e., location) to all signs, and implement a program to identify, prioritize, and replace signs that do not meet MUTCD standards or other defined criteria. The inventory system was to include a web-based application accessible by anyone in the agency without the need for special software.
TDOT planned to expand the sign inventory system to other counties and local routes in the future if this project was found to be successful.
The project included five primary tasks:
Task 1–Project Initialization and Management. This task included coordinating administrative issues between TDOT, the consulting firm, and sign manufacturer, as well as obtaining and formatting the GIS centerline data and ortho-photography for the routes and counties involved in the project.
Task 2–Data Collection. This task included the initial collection of the global positioning system (GPS) position and digital image of signs. This information was collected by vehicles equipped with GPS units, digital cameras, and mobile computers.
Task 3–Data Post Processing. Data collected in Task 2 was processed to record sign attributes such as MUTCD code and description, sign placement location (right, left, overhead), sign face orientation to nearest cardinal direction, county, route, log mile, sign dimension, sign substrate material, and support type and material. This was all determined from the digital images. In addition, each sign was given a preliminary assessment rating from good to critical based on characteristics such as fading, deterioration, and alignment. This post-processing included a quality control element during which reviewers selected random records to determine the accuracy of the entered attribute data.
Task 4–Sign Assessment and Engineering. This task included both a nighttime retroreflectivity assessment of the sign sheeting and a daytime engineering assessment of each sign in the inventory developed in Task 3. For the nighttime assessment trained personnel evaluated each sign from a moving vehicle and recorded the assessment rating for retroreflectivity. The daytime assessment was used to evaluate sign application and recommend changes such as adding additional signs, replacing with larger signs, raising the sign or changing its location, or other recommended maintenance tasks to make the signs comply with MUTCD standards. The sign database was updated to reflect the nighttime and daytime assessments, observations, and recommendations.
Task 5–Deliverables and Documentation. The final deliverables for this project included:
The overall cost of the RSIP sign inventory project was $813,500.
The sign inventory program included all signs on state routes in the 21 rural counties in the Delta region of Tennessee. The program enables TDOT staff to systematically evaluate all the signs in their inventory for compliance with MUTCD standards including retroreflectivity, and to prioritize and schedule the replacement of signs that do not meet standards without unnecessarily replacing signs that still meet criteria. The program allows TDOT to focus resources on identified needs.
The following summary statistics describe the extent of the project:
Several benefits, challenges, and lessons learned from the project include the following:
The initial capture of sign assets in the field using digital cameras was a quick way to develop the initial sign inventory database, but there were some limitations. There were situations in which signs were blocked by obstructions or foliage, or the digital image was not clear due to sun glare or weather conditions.
The initial mobile image capturing effort took longer than anticipated due to the fact that TDOT maintains regulatory signs on non-state route approaches to intersections with state routes. This meant that to record stop signs at intersections with non-state routes, the data collection vehicle had to turn onto the minor route and make a U-turn to face the stop sign of the minor route, cross the state route and make another U-turn on the opposing leg to capture that sign, and then turn back onto the state route to continue.
Agencies must anticipate the storage space required to save digital images of thousands of signs. In addition, a plan must be developed to transfer images taken in the field to office computers for post-processing and inclusion in the inventory database. For this project, external hard drives were used to transfer images.
Post-processing in the office of the images was labor-intensive and time consuming. While image recognition technology can be used to some extent to recognize standard signs, custom and non-standard signs require a human interface. Additional sign attributes also require human evaluation. However, the initial level of effort to develop the inventory would not be required for subsequent updates, which would focus only on ongoing maintenance needs or changes made to the inventory.
Sign attributes such as sign dimensions and offset distance were approximated in the office using the digital images rather than measured in the field. This provided a substantial time savings and was found to provide measurements within tolerable thresholds.
Nighttime data collection must be completed during hours of complete darkness, so summer nights provide fewer working hours than winter nights. Condensation, fog, frost and other weather and temperature-related factors that can obstruct retroreflectivity measurements should be considered when scheduling the time of year to conduct the assessment.
The sign inventory system was specifically developed to allow field staff to update sign attributes after routine maintenance in an easy-to-use web-based tool. The web-based tool makes it convenient to update the inventory system and keep it current so that it can be used to manage sign assets.
At this time, the sign inventory system has not been expanded to other areas or regions of Tennessee; however, state officials have considered options, scenarios, and funding to expand the system to other areas of the state.
Agency: Missouri Department of Transportation (MoDOT)
Focus of Evaluation: Implementation of Dynamic Message Signs and Closed-Circuit Video
Project Background
In 2005, MoDOT began the Smooth Roads Initiative, which included many thousands of miles of improvements to the state's most heavily traveled roadways. To help manage the many construction projects, MoDOT used 40 portable changeable message signs along two major Interstates. Recognizing the benefits of these signs, MoDOT decided to seek a more permanent solution for providing real-time information to the traveling public. For this reason, they began a program of installing dynamic message signs (DMSs) and closed circuit television cameras (CCTVs) around the state. In case of an incident, the CCTVs can be used to verify the location and severity of the crash and help to reduce emergency response times. The DMSs can also be used to warn motorists and direct them to bypass routes when incidents block major routes.
MoDOT received funding through the RSIP to install six DMSs, upgrade fiber optic connectivity between the signs, and install 13 CCTVs to relay information to the traffic management center in St. Louis. The DMSs and CCTVs were installed along I-57, I-55, and US 60 in the Delta Region. The project was designed to complement DMS installations already programmed around the state. Total project costs were estimated at approximately $1,000,000, broken down as follows:
$500,000 to design and install six new DMSs in the Delta Region
$30,000 for a research project to evaluate and quantify benefits of DMSs and CCTVs
$370,000 for telecomm upgrades
$100,000 to design and install camera equipment. Construction and installation began 2009 and was completed in 2010.
The successful deployment of DMSs on I-70 and I-44, following the 2005 Smooth Roads Initiative, became a springboard for providing DMSs on other rural interstates, particularly in northwest and southeast Missouri. Prior to the RSIP project, MoDOT had already decided to install some DMSs along I-55 in southeast Missouri. When the RSIP was initiated, MoDOT identified six new locations in the Mississippi Delta Region eligible for RSIP funding at which to install additional equipment that would complement the already planned DMS installation. Those sites were along the I-55, I-57, and US 60 corridors. The signs were located prior to key decision points so that customers would have time to make a decision and change their travel plans based on the information, if necessary. For example, signs were installed on US 60/I-57 just before a motorist would get to I-55. Likewise, DMS further west on US 60 were installed just before US 67 and US 63.
Some of the devices installed as part of the RSIP project are connected by fiber. A telecommunication company owns the fiber that was utilized. MoDOT has an agreement in place to access the fiber under certain circumstances. Devices not connected by fiber rely on cellular communications. While MoDOT did not install the devices, they have taken care of general maintenance for the devices since the completion of the project.
MoDOT reported that they use the CCTVs and DMSs in a variety of ways. The DMSs are used to display a message 24/7. If appropriate, the DMSs may be used to provide information about an incident, a work zone, detours, AMBER alerts, weather conditions, or other emergency information. If no such messages are needed at a given DMS, then that DMS will display a public service announcement (PSA) message related to highway safety, such as PLEASE BUCKLE UP, ARRIVE ALIVE, or PLEASE DO NOT TEXT AND DRIVE. MoDOT utilizes a pre-approved rotation of these PSA safety messages, and operators utilize this list of messages to provide motorists with a variety of information so that the same message is not continuously displayed for days and days. The PSA safety messages never take priority over messages about incidents, work zones, weather or other operational and safety issues specific to the route at that time. Because travel time information is not currently available in the rural parts of the state, the DMSs installed as part of the RSIP project display a relatively high proportion of the PSA safety messages. In addition to the general PSA safety messages, the DMSs may also be used for special campaigns such as Click It or Ticket, Drive Sober or Get Pulled Over, and Work Zone Awareness Week. A number of campaigns have taken advantage of the DMS to spread the word, and MoDOT's transportation safety partners are appreciative of this avenue for spreading their messages during highway safety campaigns. An excerpt from the message log of one of the DMSs is shown in Figure 10.
Source: MoDOT Staff
Figure 10. RSIP Project 32: Excerpt of Message Log from One DMS
The CCTVs provide a continuous source of system surveillance utilized by MoDOT staff across the state. They provide staff with real-time field conditions related to traffic flow, incident management, and weather. On a day-to-day basis, the cameras are preset at positions to provide general surveillance of the transportation system. When other events take place, the cameras are used to monitor activities and status of specific events. Such events include crashes that adversely impact traffic flow or block a lane(s). Likewise, the cameras may be used to monitor the impact of a work zone on traffic flow. The other critical service the cameras provide is a visual assessment of field conditions during adverse weather. The cameras can be used to verify road conditions during storm events, thus providing confirmation to operators and customer service representatives that are providing customers with real-time traveler information. In addition, the camera feeds are made directly available to the general public through MoDOT's Traveler Information Map and mobile application. The camera feeds can also be shared with local media for inclusion on local traffic reports. The cameras are also used for incident response in the rural areas. Typically incidents are not first identified on the camera (so response time is not necessarily affected by the cameras), but the cameras allow for better monitoring of the situation and, ultimately, more efficient clearing of the incident. The cameras also provide the ability for customers to evaluate the route and check for incidents and work zones from a computer at home or work before choosing their travel route.
MoDOT hired researchers at the University of Missouri-Columbia to conduct a formal evaluation of some of the DMS used in the region of the RSIP project. The final report titled Evaluating the Benefits of Dynamic Message Signs on Missouri's Rural Corridors (Edara et al., 2012) is available on MoDOT's website. The evaluation consisted of three separate studies. The first was an in-person survey of motorists in the study corridor (conducted at a gas station and at an exit near the regional airport) asking about sign visibility, message clarity and accuracy, the perceived impact of the signs on safety, and whether the driver took action (such as slowing or changing route) based on the sign message. Responses were categorized by trip purpose (work or recreation), vehicle type (truck or private), residency (local or visitor), and gender of respondent for analysis. In all categories, the responses were overwhelmingly positive.
The second study was a measure of speed change between a location upstream and downstream of a DMS at two locations, each with a different message being displayed. In the first case, the DMS read "ROAD WORK AT MM 117 EXPECT DELAYS", and in the second it read, "TWO WAY TRAFFIC AHEAD USE CAUTION". For both cars and trucks, statistically significant speed reductions between the upstream locations and the downstream locations ranged from about 1 mph to about 4 mph.
The third study evaluated the impact of the DMSs on diverting traffic to a detour route during a full freeway closure. I-57 was closed for four days at the Missouri-Illinois border for repairs on the Mississippi River bridge. The researchers measured evening peak traffic flow at 15 points along the detour route both before and during the bridge closure for comparison and found a significant increase in traffic along the detour route. Traffic flow was modeled in simulation software to estimate the delay savings realized by taking the detour route suggested by the DMS compared to traveling along the intended route until seeing the static bridge closure signs and making a U-turn to travel back to the detour route turn-off. Several scenarios were modeled which each assumed a different percentage of drivers were aware of the freeway closure prior to beginning their trip. The research team estimated a delay savings between 35 and 400 hours for the three-day closure studied, depending on the assumption regarding the percent of drivers who would be aware of the detour route even without the DMS. This translates to a savings of between $5,000 and $55,000 per similar event. Researchers noted that in rural areas the treatments do not provide as much travel time savings as in urban areas simply because of lower traffic volumes. However, since fewer alternate routes tend to be available in rural areas, drivers have a greater need to be informed of an available detour.
As part of the third study, researchers also surveyed drivers at a truck stop near Cape Girardeau, a town along I-55, which was part of the 38-mile detour route. Respondents were asked whether they saw the DMS with the bridge closure information, if they were previously aware of the bridge closure, if they trusted the accuracy of the signs, and if the signs provided sufficient detour information. The surveys revealed that while several travelers reported knowing of the closure from radio and newspaper, about 40 percent listed the DMS as their only source of information regarding the closure. The researchers found that, overall, drivers were satisfied with the DMSs and trusted the detour route information provided. Commercial truck drivers gave slightly higher ratings than drivers of passenger cars.
MoDOT staff has found motorists to be very appreciative of information regarding incidents, work zones, detours, road conditions and other emergencies. The PSA messages that are also posted on DMSs have not been formally evaluated, though drivers sometimes contact MoDOT regarding those messages. Usually, driver feedback is in the form of suggestions for specific messages. Drivers also often request travel time information, similar to what is available on systems managed in a traffic management center in the more urban areas, but this feature is not available in the rural deployments at this time.
While a formal benefit/cost ratio has not been conducted on the CCTVs and DMSs, MoDOT believes them to be cost effective. To date, the maintenance costs have been minimal, and the range of benefits include continued system surveillance, provision of valuable information to travelers, monitoring of traffic incidents and work zones in real time, and verifying weather and pavement conditions.
MoDOT did not identify any major roadblocks to successful implementation of the CCTV cameras and DMSs, but one issue related to utilities was identified:
Coordination with electric co-ops in the area shouldn't be underestimated. This project impacted 6 different electric co-ops across the state. Each of these entities has their own policies and procedures, so working out power requests and response times can vary from one company to the next. Depending on the cooperation of these electric companies, design work can hit a snag at different points during the process.
MoDOT reported that some additional DMSs and CCTVs have been installed since the completion of the RSIP project. These installations have typically been to fill a gap in a region with existing traffic monitoring equipment, such as outside of St. Louis and in the Springfield area. While these deployments were not added as direct results of the RSIP project, the success of the RSIP project provided additional support and justification for the installations. MoDOT staff indicated that if the RSIP project had not produced the benefits seen in the rural regions, the effort to fill in gaps on the major roadway system might have been weaker. While MoDOT is filling in gaps on the major system, a large-scale rural deployment of CCTVs and DMS in the near future is neither planned, nor likely to take place.
| < Previous | Table of Content | Next > |
