The LEAMaple LeafDRS Program

Results-Based Traffic Safety for Community Teams

RED DEER MARKET
INTERSECTION ISSUE OF THE WEEK

It became evident in 2007 that Program personnel would have to obtain their own results in order to demonstrate the features of a results-based traffic safety program. As we observed intersection traffic movements and collected data about seat belt compliance, signalling prior to changes in lane or direction, and cell phone use by drivers, we became aware of many hidden hazards.

At our Saturday morning booth at the Red Deer  Public (Farmers' ) Market we share information about these hazards and related issues with Red Deer road users.

 

Weekly Presentation Materials

 Intersection Conflicts                                May 22, 2010

This presentation helps drivers to recognize some of the challenges in navigating a complex intersection successfully. It does this by identifying traffic conflict points for vehicles leaving the west Service Road and east Service Road in order to proceed south or north on Gaetz Avenue in Red Deer. A traffic conflict occurs when the paths of road users cross.

Example I:   West Service Road through 22 Street eastbound
                    to Gaetz Avenue southbound

The intersection of Gaetz Avenue (also known as 50 Avenue, Provincial Highway 2A) with 22 Street from the west and Boyce Street from the east is located in the south end of Red Deer. Gaetz Avenue is a two-way north-south arterial roadway. 22 Street and Boyce Street are two-way east-west roadways: 22 Street is on the west side of Gaetz Avenue; Boyce Street is on the east side. Two service roads parallel Gaetz Avenue with the west Service Road connecting at 22 Street and the east Service Road connecting at Boyce Street.

Figure 1 shows the path for a vehicle traveling south on the west Service Road, passing through 22 Street and then continuing south on Gaetz Avenue. North is at the top of the figure.

Figure 1: Path of Southbound Vehicle from west Service Road
              to Gaetz Avenue South

Figure 2 shows the traffic conflicts for the southbound vehicle. Pedestrian conflict points are shown in green, vehicle conflict points are shown in black.

Figure 2: Traffic Conflict Points for Vehicle from West Service Road
              to Gaetz Ave South

There are two, two-way pedestrian conflict points: one is at the junction of the west Service Road with 22 Street; the other is in the southbound right-turn channel.

There are four conflict points for vehicles approaching from the driver's left (east). One is south traveling traffic on Gaetz Avenue that turns right (west) to 22 Street. Two conflict points are created by through traffic from Boyce Street that continues westward. The fourth is traffic traveling north on Gaetz Avenue that turns left (west) to 22 Street.

There are two conflict points for vehicles approaching from the driver's right (west). Traffic in the centre lane may be intending to turn left (north) to the West Service Road, turn left to Gaetz Avenue north, or continue straight through the intersection to Boyce Street eastward. Traffic in the curb lane should be intending to travel straight across Gaetz Avenue to Boyce Street eastward.

There are two conflict points with merging traffic: one is with 22 Street eastward to Gaetz Avenue southward traffic at the right turn channel; the other is with Gaetz Avenue southbound traffic at the exit of the right turn channel.

The driver of a vehicle traveling south on the west Service Road, passing through 22 Street and then continuing south on Gaetz Avenue has a demanding challenge in safely negotiating the path through the various conflict points. Adding to his or her task difficulty is the likelihood that some of the vehicle drivers of the conflicting streams may be unfamiliar with the complex intersection; consequently, their observed behaviour may not be a reliable basis for predicting their next movements. Further, all the other road users appear to have the right-of-way: none of them should be expected to yield.

Example II:   East Service Road through Boyce Street westbound
                     to Gaetz Avenue northbound

Figure 3 shows the path for a vehicle traveling north on the east Service Road, passing through Boyce Street and then continuing north on Gaetz Avenue.

Figure 3: Path of Northbound Vehicle from East Service Road
              to Gaetz Avenue North

Figure 4 shows the traffic conflicts for the northbound vehicle. Pedestrian conflict points are shown in green, vehicle conflict points are shown in black.

Figure 4: Traffic Conflict Points for Vehicle from East Service road
              to Gaetz Avenue North

There are three, two-way pedestrian conflict points: one is at the junction of the east Service Road with Boyce Street; two are at the northeast corner of the intersection of Boyce Street with Gaetz Avenue.

There is one conflict point for vehicles approaching from the driver's left (west). Because  traffic may be coming from the north, west or south, the driver must check that all three sources are clear of encroaching vehicles.

There are two conflict points for vehicles approaching from the driver's right (east). Traffic in the centre lane may be intending to turn left (south) to the east Service Road, turn left to Gaetz Avenue South or continue straight through the intersection to 22 Street westward. Traffic in the curb lane should be intending to travel straight across Gaetz Avenue to 22 Street westward to turn right to Gaetz Avenue northward.

There is one conflict point with merging traffic; namely, with Gaetz Avenue northbound traffic in the curb lane.

Similar to but not quite as complicated as Example 1, the driver of a vehicle traveling north on the east Service Road, passing through Boyce Street and then continuing north on Gaetz Avenue has a demanding challenge in safely negotiating the path through the various conflict points. Adding to his or her task difficulty is the likelihood that some of the vehicle drivers of the conflicting streams may be unfamiliar with the complex intersection; consequently, their observed behaviour may not be a reliable basis for predicting their next movements. Further, all the other road users appear to have the right-of-way: none of them should be expected to yield.

Comments:

1. According to the City of Red Deer, the intersection of Gaetz Avenue with 22 Street/Boyce Street and the two service roads, ranked 4th place in terms of severity index, 6th place in terms of collision frequency, and 11th place in terms of collision rate.

2. The intersection of Gaetz Avenue with 22 Street/Boyce Street and the two service roads is one of several different configurations of signalized intersections in Red Deer. The process used to identify traffic conflict points in this article can be used at the other locations to reduce the likelihood of collision involvement.

The Alberta Basic Driver Handbook and its companion Geared to Go coaching workbook do not introduce learner drivers to such complex intersections.

3. There is a donut shop at the southwest corner of the intersection. Sitting at one of their tables facing the intersection would provide an opportunity for young drives and their coaches to observe the complex movements of vehicles through the intersection without distracting the drivers. Friday and Saturday afternoons, especially prior to Christmas, can be excellent learning periods.

Index of
Weekly Materials

May 22, 2010
    Intersection Conflicts


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