Grand Coulee Access Road and Highway 1 Intersection

The Highway 1 and Grand Coulee Access Road intersection serves a mix of commuter, provincial and national traffic and is a critical link serving people and businesses in the RM of Sherwood (RM) and Town of Grand Coulee (Town). It is the first major intersection west of the Highway 1 and Regina Bypass interchange.

In 2018, a proposal for a commercial development near the highway was received from a developer wanting to build a gas bar with convenience store, two fast-food restaurants and a truck fuelling station. The study looked at modifications to improve safety and traffic flow at the intersection including turning lanes and acceleration lanes.

In 2020, the Ministry of Highways decided to study additional safety and traffic flow improvements at this intersection in order to improve traffic operations and delay the need for a potential overpass.

Traffic signals were not viable option. A major investment has been made on the Highway 1 Bypass and there is a need to maintain a 110 km/h speed on Highway 1. Traffic signals would reduce free flow conditions for traffic on Highway 1 and may surprise drivers, potentially leading to safety issues.

Intersection design options were developed based on current development plans by the RM and Town.

The study looked at several design options. A survey was then conducted to get the perspective of a wide variety of stakeholders.

Rural Municipality of Sherwood Official Community Plan 2016

The Rural Municipality of Sherwood Official Community Plan includes:

1. Rural residential development along the Grand Coulee Access Road;
2. Highway commercial and industrial development along Centre Road; and
3. Soil protection for agricultural use.

Grand Coulee Official Community Plan 2012

The Town of Grand Coulee Official Community Plan identifies development to the north and east of the existing town, including residential, commercial, business park and railway industrial land uses.

Some of the items considered when examining upgrades at intersections:

• What is the cost to build and maintain it?
• Does it allow development to the south?
• Can it accommodate an increase in traffic volume?
• What is the impact to agricultural land surrounding the intersection?
• How does it benefit area residents?
• How does it accommodate trucks?
• How does it improve safety?
• Is there potential for wrong-way movements?
• How much additional land is needed?
• Does Highway 1 remain free-flow?
• How does it impact the Regina Bypass?
• Is speed reduction required?
• Will it meet driver expectations?
• Does it meet industry standards and best practices?
• Does it provide space for a future overpass/interchange?
• Can it be used elsewhere within Saskatchewan?
• How quickly and easily can it be implemented?

The timing of improvements will depend on surrounding residential and highway commercial development. There could be an opportunity to build in stages.

The study options examined within the project included:

• Base Case - Standard Auxiliary Lanes
• Option #1 - Directional Island
• Option #2- Wider Median
• Option #3- Restricted Crossing U-turn
• Option #4 - Offset Limit (preferred option)

For each option, you will find an illustration, description, advantages and disadvantages and a video description. There is also animation of the preferred option.

Base Case

The base case option includes a right-turn lane for traffic travelling west on Highway 1. There is a left-turn lane for traffic heading east. There is also an eastbound acceleration lane for vehicles entering the highway from Grand Coulee Access Road.

Option 1 - Directional Island

Option 1 improves safety and traffic flow at the intersection by introducing two key features:

1. A directional island along eastbound Highway 1; and
2. Right-turn ramps to and from Grand Coulee Access Road.

The directional island creates a T-intersection, which reduces the number of turns occurring, simplifies traffic operations and potential for collisions. Access to the area south of the intersection is available using a right-in/right-out.

The right-turn ramps remove the right-turning traffic from the Highway 1 and Grand Coulee Access Road intersection. The ramps reduce the number of conflicts, reduce the severity of potential collisions, and improve visibility for the intersection.

Advantages

1. Reduces the number of conflict points.
2. Right-turn ramps reduce the amount of traffic entering the intersection and makes it easier for motorists to judge traffic manoeuvres and gaps.
3. Right-turn ramps offer space to build a potential future interchange.
4. Visibility is improved by separating the southbound right and left turns.
5. Accommodates development traffic growth to the north of Highway 1. 

Disadvantages:

1. Some movements to and from the south are restricted.
2. The speed limit on Highway 1 must be slightly reduced at this location.
3. Motorists may be unfamiliar with a median island on the highway.

Option 2 - Wider Median

Option 2 allows trucks to queue in a wider median while turning. This is accomplished by moving Highway 1 eastbound lanes further south.

The right-turn ramps remove the right-turning traffic from the Highway 1 and Grand Coulee Access Road intersection. This allows drivers entering Highway 1 to focus on one direction of traffic at a time. The ramps reduce the number of conflicts, reduce the severity of potential collisions and improve visibility.

Acceleration lanes allow vehicles from Grand Coulee Access Road to accelerate up to 110 km/h prior to merging with Highway 1 traffic.

Advantages:

1. Intersection accommodates traffic from all directions.
2. Existing speed limit of 110 km/h is maintained.
3. Increased median width allows trucks to wait in the median before turning.
4. Right-turn ramps offer space to build a potential future interchange.
5. Drivers are familiar with this type of intersection.
6. Sight lines are improved.

Disadvantages:

1. Requires Highway 1 lanes to be moved to achieve wider median.
2. Wider median requires a longer bridge should a future overpass be needed of Highway 1.
3. This option costs the most.
4. More conflict points.

Option 3 - Restricted Crossing U-turn (RCUT)

Option 3 eliminates left turns and through traffic from Grand Coulee Access Road. These drivers turn right onto Highway 1 and then make a U-turn at the median.

Left-turns from Highway 1 would be similar to a typical intersection.

This option replaces high-risk left turns at the intersection with less risky right turns. This results in fewer conflict points.

Advantages:

1. Fewer conflict points.
2. Fewer right-angle (T-bone) collisions.
3. Lowest cost of construction.

Disadvantages:

1. RCUT's are not typically used at high traffic intersections.
2. Potential increase in sideswipe collisions.
3. Potential weaving issues for slow-moving vehicles such as large trucks.
4. Increased travel time for highway commercial development and Grand Coulee residents.
5. Drivers using Grand Coulee Access Road must make unusual manoeuvres.
6. The speed limit on Highway 1 must be slightly reduced at this location.
7. Cannot be staged into an interchange.

Option 4 - Offset Lefts (Preferred Option)

Example of traffic flow at peak hour traffic volumes:

Option 4 creates two T-intersections on Highway 1. The west intersection allows left-turns onto Grand Coulee Access Road. The east intersection allows left-turns from Grand Coulee Access Road. The intersections are joined using a single-lane roundabout.

It also includes right-turn ramps and acceleration/deceleration lanes to allow traffic to transition to/from highway speeds.

This option improves traffic flow and safety by allowing drivers to focus on one direction of Highway 1 traffic at a time. The intersection greatly reduces the number of conflict points and the severity of potential collisions. The separation of all turning movements improves visibility while turning.

Access to the south of Highway 1 and Grand Coulee Access Road will be available using a right-in/right-out.

This option rated the highest and is the preferred option.

Advantages:

1. Fewest number of conflict points.
2. Reduces amount of traffic entering the intersection, which makes it easier for motorists to judge gaps.
3. Drivers focus on one direction at a time.
4. Right-turn ramps offer space to build a potential future interchange.
5. Visibility is improved by separating southbound right and left turns.
6. Existing Highway 1 speed limit of 110 km/h is maintained.
7. The roundabout accommodates large trucks, minimizes traffic delay and provides intuitive guidance.
8. Commercial and residential development can occur north of Highway 1.
9. A minor amount of development can occur south of Highway 1 with access provided via a right-in/right-out.

Disadvantages:

1. Some movements to and from the south are restricted.
2. Design may be unfamiliar to drivers.
3. Second highest construction cost.

This survey is now closed.

Thank you for your participation. Your input is valued.

When will the new intersection be built?

That depends on the timing of residential and highway commercial development using the intersection.

Will intersection improvements be constructed all at once?

We will consider building in stages, but this will depend entirely on development growth and resulting traffic demand. Our goal is to develop an intersection that will defer the need for a costly interchange.

For more information or to provide additional input, contact:

Nathan Gray
Manager, Transportation Planning
WSP Canada
Phone: 306-518-0231
Email: nathan.gray@wsp.com