Congestion Management System

Chapter 7: Summary and Future Considerations

To conclude the CMS plan a summary of results and recommendations for future steps that should be taken will be presented in this chapter.

7.1: Summary of Recommended Strategies
Table 7-1 summarizes the recommended congestion mitigation strategies for each corridor that has been identified as congested in the Knoxville TPO study area. The selection of strategies was performed by separate taskforces from Knox and Blount counties as described in Chapter 4 of this document. Appendix C includes summaries of detailed information for each corridor that was used to determine the appropriate mitigation strategies for each.

The most frequently recommended mitigation strategies are the ones under strategy class #1, which deal with Transportation Demand Management. It was believed that these strategies tend to be system-wide rather than corridor-specific, and that all corridors could benefit in the reduction of travel demand. The TPO is initiating a program known as “Smart Trips” which will attempt to achieve many of the goals of this strategy class through initiating employer programs to reduce commuting trips through programs such as transit passes, alternative work arrangements and carpooling incentives among others. One component of the Smart Trips program will be to assess its effectiveness, which can be used to justify its future expansion and role in the TPO’s transportation planning priorities.

The next most frequently recommended mitigation strategy was that of Traffic Signal Improvements (Strategy 2A). This strategy was chosen for several routes because of the key role that traffic signals play in the traffic operation along arterial roadways in the TPO area. There are in fact four corridors on the congested corridor list that are proposed to receive Congestion Mitigation/Air Quality (CMAQ) improvement funding to retime and synchronize the traffic signals:

• Chapman Highway/Henley Street–Woodlawn Pike to Clinch Avenue
• Middlebrook Pike–Cedar Bluff Road to College Street
• Western Avenue/Summit Hill Drive–Palmetto Road to E. Hill Avenue
• Clinton Highway–Tillery Road to McClain Drive

Again, the actual implementation of the selected strategies will depend on the process that was described in Chapter 6 whereby future updates of the LRTP and TIP will incorporate the CMS findings into the project selection process. In addition, local jurisdictions can use the information from the CMS to target less intensive improvements such as signal timing upgrades or other related maintenance activities that would not fall under a capital project type programming process.

7.2: Extent of Congestion
The amount of roadways that qualified as congested according to the methodology used in the CMS plan are summarized for each of the two major performance measures in order to provide an estimation of the total extent of congestion occurring at the present time. The extent of congestion will be monitored in future CMS reports in order to track the amount of change in congestion over time in the Knoxville Urban Area. The following tables present the percentages of miles in the study area that are operating at each level of congestion for performance measures #1 and #2 respectively.

 

TABLE 7-2 Percentage of Miles by Congestion Category under Performance Measure #1 Performance Measure # 1 - Volume to Capacity Ratio

CONGESTION CATEGORY	KNOX COUNTY % Miles Congested	BLOUNT COUNTY % Miles Congested
Serious	27.20%	8.79%
Moderate	21.70%	11.13%
Marginal	8.05%	7.10%
Not Congested	43.05%	72.98%

 

TABLE 7-3: Percentage of Miles by Congestion Category
under Performance Measure #2 Performance Measure # 2 - Travel Time

CONGESTION CATEGORY	KNOX COUNTY % Miles Congested		BLOUNT COUNTY % Miles Congested
	AM Peak	PM Peak	AM Peak	PM Peak
Serious	2.74%	6.18%	0.23%	2.24%
Moderate	6.70%	8.18%	10.43%	9.68%
Marginal	8.04%	5.84%	9.65%	1.86%
Not Congested	82.52%	79.80%	79.69%	86.22%

 

7.3: Future Considerations
The Congestion Management System is a continuous process that will need to be updated in the future, and as such there are several enhancements that should be investigated and incorporated into future updates, as they are deemed feasible. The CMS will need to evolve to be consistent with the goals and objectives of transportation planning, as they happen to change over time. The following specific enhancements could both facilitate the process of identifying congestion and provide more information to the CMS, and are suggested in order of priority:

(1) Include Additional Transportation Modes: Since the intent of the CMS regulations is that the multimodal transportation system is included in the analysis, the Knoxville TPO will need to investigate how additional modes can be incorporated into the CMS for congestion monitoring. The most important modes to include first will likely be that of transit and freight movement.

(2) Develop Comprehensive Travel Time Database: A comprehensive database that includes travel time data from the 1997 study and all subsequent studies will allow for important comparisons to be made that can determine the growth in congestion, and effectiveness in the congestion mitigation strategies.

(3) Use of Travel Demand Forecasting Model: As was mentioned previously in this report, the TPO is retaining consulting services to update its travel demand model in the TransCAD software platform. The model will likely replace the “EVE” analysis process used in this plan to determine current and future volume-to-capacity ratios. In addition, the travel model can be used to better assess the impacts of non-traditional strategies such as travel demand management than other methods currently available to the TPO.

(4) Updated Congestion Performance Measures Based on Travel Time: The TPO will investigate possible changes to the methodology used to define congestion based on travel time. The current methodology of comparing peak travel time to off-peak travel time has some faults, mainly in that the true “off-peak” travel time is not easily obtained since it would require driving at odd hours of the day, usually in the middle of the night. There are other methodologies for assessing travel time performance that are included in the latest edition of the Highway Capacity Manual (2000 edition), particularly the urban streets section that could be substituted for the current methodology.

(5) Investigate Reverse Commuting Patterns: When performing the travel time studies it was always assumed that the peak direction of flow was in the direction towards the central business district in the morning and the opposite in the afternoon. It was often observed though that traffic was equally heavy, if not more so, going in the reverse direction of this traditional pattern on certain key facilities such as the Interstate. Therefore, during the next set of travel time studies, the reverse commute should be included.

(6) Expand Data Collection Activities: Although data collection is a very time consuming and labor intensive activity, there is always room for improvement in the amounts and types of data that are collected. One addition in particular to the data collection program that would assist in the assessment of the effectiveness of travel demand management techniques is that of vehicle occupancy counts. The TPO will explore the possibility of adding vehicle occupancy counts to its data collection program.

Another enhancement to the data collection program would be the addition of permanent count stations located on various facility types to determine daily and seasonal fluctuations in traffic patterns. This data would be especially useful in determining whether travel time runs are actually being performed on a “typical” day.