8. Conclusions and Recommendations

8.1 Conclusions

The travel demand forecasting, INTEGRATION modelling, traffic operations analysis and safety assessment documented in this report support the following conclusions about the existing configuration of the Highway 417 corridor between Highway 416 and Anderson Road:

Travel Demand Forecasting and Traffic Volume Projections:

• Continuing population and employment growth in the City of Ottawa will result in significant growth in travel demands through the Study Area. Growth will be higher at the eastern and western ends of the Study Area than through the central section.
  
• With no improvements to Highway 417 through the Study Area, traffic volume growth on Highway 417 will be capacity constrained, resulting in lengthening of peak periods, increases in travel delays, and diversion of long distance trips to the local road network.
  
• If the capacity of Highway 417 through the Study Area is increased, traffic will be attracted from other facilities or from the shoulders of the peak periods until a new equilibrium is reached. No significant change would be expected to the level of service on Highway 417, but an overall improvement in network operations would be achieved.
  
• Major network improvements (inter-provincial bridges, Outer Transportation Corridor) do not significantly change the travel demands on Highway 417 through the Study Area, but they do enhance overall network performance.

INTEGRATION Modelling and Operations Analysis:

The results of the INTEGRATION modelling and mainline operations analysis for each horizon year are summarized on schematic maps in Appendix F.

• With a few minor exceptions, traffic operations on Highway 417 through the Study Area are projected to deteriorate over the next 20 years if no improvements are implemented.
  
• Existing areas of congestion are projected to expand over time. Substantial growth in congestion is expected:
  • Westbound from Walkley Road or Hunt Club Road through the Ottawa Road 174 interchange in the a.m. peak period;
  • Westbound from Ottawa Road 174 into the downtown area in the a.m. peak period;
  • Westbound from the downtown area towards Highway 416 in the p.m. peak period;
  • Eastbound from the Pinecrest Road/Greenbank Road interchange toward the downtown area in the a.m. peak period; and
  • Eastbound from the downtown area to Ottawa Road 174 in the p.m. peak period.
    
• Traffic operations analysis indicates that acceptable operations could be restored throughout most of the Study Area, and maintained through 2021, by undertaking basic lane widening, addition of continuous auxiliary lanes at specific locations, and widening of certain ramps. Details are provided in Table 6.3 and Table 6.4. This result does not reflect the traffic demand diversion predicted by the TRANS model, as noted above and does not consider the technical feasibility or environmental impacts of the widenings.
  
• Many of the ramp terminal intersections (26 in total) throughout the Study Area have existing traffic operations problems or are expected to develop problems in the future, most within 10 years (see Table 6.5).

Safety Review:

• Statistical analysis of the 1998 through 2001 collision history at 259 locations identified a total of 106 locations with higher than expected collision probabilities. Of these, 76 were found to have a higher collision probability than expected for the group of all similar locations (e.g. all mainline sections between interchanges) within the Study Area. These Primary locations have the greatest potential for safety improvement. The other 30 locations are considered Secondary, with a lower but still significant potential for safety improvement.
  
• The most common factor identified as contributing to the collision history in the locations with higher than expected collision probability was recurring congestion.
  
• Restrictive geometric design was also found to be a significant contributing factor, particularly when combined with heavy traffic volumes and recurring congestion. Examples include short acceleration, deceleration and weaving distances, tight interchange curve radii and restricted sight distances.
  
• Mainline sight distance deficiencies identified in the Existing Conditions Report -- Highway Geometrics were found to correlate with locations of higher than expected collision probability.
  
• The positive guidance review found no systemic deficiencies in the existing geometry of the Highway 417 mainline, but identified several locations with violations of motorists' expectations (e.g. left exit, must exit lane, exit on tangent to mainline curve, etc.). These locations were all found to be correlated with higher than expected collision probability.
  
• Signage and delineation were found to generally provide an adequate level of positive guidance. Some opportunities were identified for improved signage and/or delineation in areas of motorist expectation violations, restrictive geometric design and complex geometry.

8.2 Corridor Analysis Composite Plans

The INTEGRATION modelling, traffic operations analysis and safety review documented in this report identified a range of existing and projected future operations and safety issues within the primary Study Area. A review of the existing geometric design of Highway 417, completed in parallel with these analyses and documented in the Existing Conditions Report -- Highway Geometrics, identified several areas with geometric design features that do not meet current standards. To provide a comprehensive summary of the traffic operations, safety and geometric design reviews, the issues found by each have been identified by location on a set of plans. These Corridor Analysis Composite Plans, provided in Appendix I, illustrate the locations of identified operational, safety and design issues and the relationships among these issues.

The greatest potential for improvement to Highway 417 is in areas where some combination of the INTEGRATION modelling, traffic operations analysis, safety review and geometric review identified major issues. The implementation of changes in these areas would produce multiple benefits. Typical situations include capacity deficiencies that result in a high collision risk and geometric deficiencies that result in a high collision risk and/or congested operations.

A review of the plans in Appendix I reveals a number of areas with clusters of identified safety, operations and geometrics issues. These areas of high potential for improvement include an assortment of individual ramps, complete interchanges and highway mainline sections throughout the Study Area. The following table lists these areas by type, from west to east. Information on the location, severity and type of issues identified within each area is available by consulting the plans in Appendix I. Additional details on individual safety and operations issues are provided in the preceding sections and appendices of this report; geometric issues are documented in the Existing Conditions Report -- Highway Geometrics.

Table 8.1 - List of Areas with High Potential for Improvement

8.3 Recommendations

This study has established that there is a need for improvements to the Highway 417 corridor through the primary Study Area to address existing operations and safety issues and to accommodate the expected growth in travel demand anticipated by Ottawa's Transportation Master Plan. The travel demand forecasting completed as part of this study indicates that construction of (or improvements to) alternative facilities will not significantly reduce the expected increase in travel demand on Highway 417. Accordingly, the following improvements should be considered:

• Mainline Widening -- The travel demand forecasting indicates that providing additional mainline and auxiliary lanes, as indicated in Table 6.3 and Table 6.4, will not significantly reduce congestion on Highway 417 in the long term, but will provide relief to the City road network surrounding the Highway 417 corridor. Maximizing the available capacity on Highway 417 will encourage through traffic to remain on the highway, reducing traffic on local streets.
  
• Geometric Improvements -- In areas where the existing geometric design does not meet current standards, improvements such as removing sight distance restrictions, increasing ramp curve radii and increasing the available acceleration, deceleration and weaving distances can be expected to decrease the probability of collisions and facilitate smoother traffic flow. Removing violations of motorists' expectations should also be a priority, as these are correlated with higher than expected collision probabilities and can also disrupt smooth traffic flow.
  
• Intersection Improvements -- Improvements to increase the capacity of the critical movements identified in Table 6.5 should be considered at each intersection. Possible solutions could range from signal operations changes to additional auxiliary lanes to complete redesign of the intersection. Detailed analysis will be required to determine the effectiveness of potential improvements at each location. Operational improvements to reduce queue lengths should be considered where future operating conditions indicate a potential for queue spill-back onto the Highway 417 mainline.
  
• Positive Guidance Improvements -- Signing, pavement marking, delineation and the overall message conveyed to motorists by the roadway and surrounding environment should be considered as part of the improvements recommended above. Particular attention will be required to locations where geometric design deficiencies or expectation violations will remain, as positive guidance improvements can help to mitigate the negative effects of these features.
  
• Congestion Management -- Recurring congestion will remain in the Highway 417 corridor, even with the implementation of significant improvements. Measures to manage congestion should be considered as part of the design of improvements in order to minimize its effects on traffic operations and safety. Application of Intelligent Transportation Systems (ITS) for congestion management is being considered as part of the Preliminary Design Study.

These recommendations are based only on the outcomes of the travel demand forecasting, INTEGRATION modelling , traffic operations analysis and safety review documented in this report. They do not consider technical feasibility, environmental impacts, property impacts or costs.

In the next stage of the Preliminary Design Study, specific, technically feasible improvement alternatives will be developed to address these recommendations. The assessment of these alternatives will include evaluation of their traffic operations and safety implications, as well as a full range of other factors, including environmental impacts, property impacts, construction costs and potential benefits. The technically preferred improvement alternatives will be selected on the basis of a complete assessment of all relevant factors, as required by the Class EA process.

Contents | Summary | Introduction | Data Collection | Demand Forecasting | Traffic Volumes
INTEGRATION Modelling | Operations Analysis | Safety Review | Conclusions