How bad will the traffic be in 2020 when bridge closes for 6 months?

In 2016 a study was done on traffic patterns and estimates half the people travelling locally between Chatham and Douglastown will opt not to make the trip. Study also predicts hot spots and suggests mitigation.

How bad will the traffic be when the Centennial Bridge closes for 6 months in 2020?  Leading up to the reconstruction of the aging bridge, the Department of Transportation and Infrastructure conducted a traffic study to determine where the hotspots will be and some steps that could be taken to mitigate the traffic jams.  The entire study can be downloaded HERE. 

Below is a summary of the recommendations and some screenshots from the report that outline some key statistics and problem areas.

Existing traffic volumes collected in the fall of 2016 were used to predict traffic pattern changes expected during the full bridge closure. This included estimating the volume of traffic that would shift from the Centennial Bridge to the Miramichi Bridge as well as identifying the travel routes that would be affected.

Traffic analyses were carried out to evaluate AM and PM peak hour traffic conditions under the baseline conditions (2020 volumes with the Centennial Bridge open) and under the full closure conditions (2020 volumes with the Centennial Bridge closed), assuming no mitigation measures are implemented. The key findings are summarized below:

 

Closure Conditions

1. The closure conditions would include a full closure of the Centennial Bridge, which would force all traffic to detour to the Miramichi Bridge. It was assumed that 50% of the local trips between destinations in Douglastown and Chatham would not be made or would be made outside of peak periods. It was also assumed that north of the river, all traffic would detour along the King George Highway and south of the river, most traffic would use Route 8, while some traffic travelling to/from Chatham would use Water Street. It was estimated that approximately 75% of the traffic diverting from the Centennial Bridge would cross the Miramichi Bridge. The remaining trips would not be made, or would be made outside of the peak periods.

2. Level of Service (LOS) results indicated that during the AM peak period, very high delays are expected at the University Ave. @ Route 8 NB Ramps intersection and moderate-to-high delays are expected at the Route 8 @ Water Street intersection and the King George Highway @ Route 8 Ramps intersection.

3. The LOS results indicated that during the PM peak period, very high delays are expected at multiple intersections throughout the Study Area. The heaviest congestion is expected to occur along Route 8 and the King George Highway near the Miramichi Bridge. The following intersections are expected to operate with moderate or very high delays:  University Avenue @ Route 8 NB Ramps (very high); Route 8 @ Water Street (very high); Hennessy Street @ Pleasant Street (very high); King George Highway @ Newcastle Boulevard (very high); King George Highway @ Route 8 Ramps/Kingsway Avenue (moderate); King George Highway @ Hennessy Street (moderate); King George Highway @ Jane Street (moderate).

4. It was estimated that the detour route for trips between Chatham and Douglastown would add approximately 19 km of travel distance and would require, on average, approximately 22-25 minutes of additional travel time per one-way trip during peak periods, compared to having the bridge open.

5. The closure of the Centennial Bridge would have a significant impact on the movement of goods throughout the Miramichi area. It was estimated that the bridge closure would result in approximately 145,500 one-way truck trips through the detour route, totaling approximately 54,000 hours of additional travel time.

6. The City expressed concerns with congestion  along the King George Highway between Cove Road and Williston Drive. It was estimated that traffic volumes along this section of the highway would double from an AADT volume of 11,200 vehicles under baseline conditions to approximately 22,500 vehicles during the Centennial Bridge closure. A highway capacity analysis indicated that during the closure period this stretch of highway would operate at a LOS E and would remain below capacity during peak periods; however, long platoons of vehicles can be expected and turning movements from private driveways and side streets would be difficult to make. Installation of temporary traffic signals could be considered at either Cove Road, French Fort Road, or Williston Drive to create more gaps in the traffic stream and thus reduce delays for turning movements from private driveways along the highway.

7. The benefits of re-opening the Morrissy Bridge to pedestrians and/or vehicles were explored. It was determined that the bridge would have to function as one-way northbound during the AM period and one-way southbound during the PM period. Opening the Morrissy Bridge to northbound traffic during the AM period would reduce the average travel time for vehicles travelling northbound on either bridge by approximately 15 seconds/vehicle. Opening the Morrissy Bridge to southbound traffic during the PM period would reduce the average travel time for vehicles detouring southbound across the Miramichi Bridge by just over 2 minutes/vehicle, while vehicles detouring southbound across the Morrissy Bridge would experience a travel time savings of approximately 3 minutes/vehicle. If opened to pedestrians only, a parking lot could be established on the south side of the bridge so people could park their vehicle and walk to the downtown (Newcastle).

8. It is anticipated that some traffic travelling to/from Route 8 north of Newcastle will avoid the King George Highway by detouring over to Newcastle Boulevard. It was estimated that as many as 120 vehicles (70 from Route 8, 50 to Route 8) may detour during the AM peak period and up to 150 vehicles (90 from Route 8, 60 to Route 8) may detour during the PM peak period. This would improve traffic operations along the King George Highway between Route 8 and Newcastle Boulevard; however, if Newcastle Boulevard were to be promoted as a detour route, it should only be for passenger vehicles and through truck traffic should not be permitted due to the classification of the street and challenging geometry at the Newcastle Boulevard/King George Highway intersection.

9. For comparison purposes, a single lane closure of the Centennial Bridge was modelled to estimate the delays that would be expected under this situation. This scenario would allow two-way traffic to be maintained on the Centennial Bridge, but alternating one direction of flow at a time controlled by traffic signals. It was estimated that with a 400 m single-lane closure on the Centennial Bridge, delays of up to 5 minutes per vehicle would be expected during the AM peak period and delays of 10-15 minutes per vehicle would be expected during the PM peak period (for vehicles crossing the Centennial Bridge). In summary, a full closure of the Centennial Bridge would cause a significant increase in traffic along the King George Highway and Route 8 near the Miramichi Bridge. This would result in significant congestion at both ends of the Miramichi Bridge and along the King George Highway. If no improvements are made, long delays and queuing would be expected near the Miramichi Bridge and along the King George Highway.

Several improvement options, as discussed below, would help to mitigate delays at the most congested locations, but many drivers would still be faced with significant travel time increases due to the length of the detour route required to cross the Miramichi Bridge.

Recommended Improvement Options

The Study Team identified several improvement options and mitigation measures that would help improve traffic flow and would help address some of the issues that are anticipated during a full closure of the Centennial Bridge. The recommended improvement options included the following locations:

- King George Highway @ Douglastown Blvd. 
- King George Highway @ Newcastle Blvd. 
- King George Highway @ Jane St. 
- King George Highway @ Hennessy St. 
- King George Highway @ Route 8 Ramps / Kingsway Ave. 
- Route 8 @ Water St / Nelson St. (not necessary if converted to a roundabout) 

University Avenue @ Route 8 Northbound Ramps – Temporary Traffic Signals

With the Centennial Bridge closed, most northbound traffic on Route 11 south would divert to Route 8 via the exit ramp onto University Avenue. This would cause a significant increase in left-turn traffic at the westbound approach of the University Avenue @ Route 8 Northbound Ramps intersection. It is recommended that temporary traffic signals be installed at this intersection while the Centennial Bridge is closed.

 
Hennessy Street – Temporary Traffic Signals and Upgrades 

Traffic volumes on Hennessy Street would be expected to increase significantly during a Centennial Bridge closure, as this is the only northbound connection between the Miramichi Bridge and the King George Highway. In order to handle this additional traffic, it is recommended that the following upgrades be made at the Pleasant Street @ Hennessy Street intersection (refer to Figure A1 of Appendix A):

 
- Install temporary traffic signals, complete with pedestrian signals for the existing crosswalk; 
- Remove the eastbound left-turn lane on Hennessy Street and re-paint the eastbound approach to accommodate a single shared left/through lane; 
- Re-paint the westbound approach on Hennessy Street to provide a through lane and shared through-right lane; 
- Program the traffic signals to provide an advanced southbound phase to accommodate eastbound left turns (traffic signal timings are included in Appendix D). 

The above signal improvements are temporary and would only be in place while the Centennial Bridge is closed. The improvements below are permanent and would provide a benefit both during and after the Centennial Bridge closure. 

King George Highway @ Route 8 Ramps/Kingsway Avenue – Intersection Upgrades

 The westbound left turn volume would increase significantly at this intersection during a Centennial Bridge closure, as all southbound traffic diverting to the Miramichi Bridge would have to turn left at this intersection. In order to accommodate the increased volume of left turn traffic, the following permanent upgrades are recommended (refer to Figure A2 of Appendix A):

- Add a pedestrian island at the southwest corner of the intersection and paint crosswalks at all four approaches;
- Add a separate channelized right turn lane at the King George Highway eastbound approach;
- Widen the northbound (ramp) approach to accommodate a longer channelized right-turn lane (this would require widening of the asphalt surface onto the existing gravel shoulder).

Route 8 @ Water Street – Roundabout

 It is recommended that NBDTI convert this intersection to a roundabout to provide operational and safety benefits, both during a bridge closure and permanently. A single lane roundabout would be sufficient under baseline conditions, but would be expected to operate at an overall LOS E with the Centennial Bridge closure in place. A multi-lane roundabout could be considered and would increase capacity during the closure period. Refer to Figure A5 of Appendix A for a preliminary concept illustrating a potential configuration with multiple entry lanes on the Route 8 approaches. 

King George Highway @ Jane Street – Intersection Upgrades 

A permanent improvement option has been identified for this intersection; however, this improvement focuses mostly on pedestrian safety and would not offer much improvement to traffic flow at this intersection. This improvement includes the following upgrades (refer to Figure A3 of Appendix A): 
- Add pedestrian islands at the southwest and southeast corners of the intersection; 
- Install pedestrian signal heads and marked crosswalks at the south and east legs. 

King George Highway @ Newcastle Boulevard – Intersection Upgrades 

A permanent improvement option was also identified at this intersection. This improvement option focuses mainly on pedestrian safety, but it would also help improve traffic operations at the northbound approach and it would provide additional space for truck turning movements. This improvement includes the following (refer to Figure A4 of Appendix A): 
- Install a pedestrian island at the southeast corner of the intersection; 
- Widen the Newcastle Boulevard northbound approach to accommodate a 15 m long channelized right turn lane; 
- Re-paint the left-turn stop bar at the east leg roughly 2.5 m further from the intersection.

King George Highway – Cove Road to Williston Drive

 It is recommended that temporary traffic signals be considered at one or more locations along the King George Highway between Cove Road and Williston Drive. These signals would force traffic on the King George Highway to stop periodically and would provide additional opportunity for traffic to enter the highway from private driveways and side streets along the highway. Traffic signals could be considered at one of the following locations: 
- Cove Road 
- French Fort Road
- Williston Drive