Path and Roadway Intersections
Prepared by Mia L. Birk, former Bicycle Program Manager, City of Portland, and George Hudson, former senior designer for the Portland Parks Bureau. Both currently work for Alta Planning + Design.
The Springwater Corridor is a 16-mile paved shared-use path that extends from Portland's inner eastside to the adjacent suburbs of Gresham and Boring. A rail-to-trail conversion, it follows power lines and is part of a larger trail system in the Portland metropolitan area known as the 40-Mile Loop.
Over half a million people use the trail annually. There are 28 locations where the trail crosses a roadway, offering an interesting case study for managing trail-roadway crossings. Almost all crossings are at locations away from existing roadway intersections, thus few before and after safety or functionality comparisons can be made. However, qualitative observations are offered where appropriate.
Evaluation of trail-roadway crossings involves analysis of the traffic patterns of vehicles as well as trail users. This includes traffic speeds, street width, traffic volumes (average daily traffic and peak hour), line of sight for both roadway and path approaches, and trail user profile (age distribution, destinations).
The existing crossings fall into the following categories:
- Uncontrolled, marked crossings: unprotected crossings include midblock crossings of residential, collector, and sometimes major arterial streets.
- Routed to existing intersection: in certain locations, the trail emerged quite close (within a few hundred feet) to existing intersections and was routed to use the existing signal.
- New signalized crossings: in four locations, new signalized crossings were installed at major roadways due to the traffic volumes, speeds, and projected trail usage.
- Grade-separated crossings: three grade-separated crossings were in place at the time of acquisition of the corridor. Two additional grade-separated crossings were constructed after the trail was installed. The trail takes advantage of the presence of these grade-separated crossings.
Type 1: Uncontrolled/Marked Crossing
Uncontrolled, marked crossing of a local street.
Most of the minor public roadway crossings along the Springwater Corridor are serviced by unprotected crossings consisting of crosswalk markings and signs. Where trail crosses a public roadway, trail users are required to stop for roadway traffic. At private driveway crossings, motorists are required to stop for trail users, as indicated by stop signs and marked crosswalks. These crossings have a low volume of traffic and are not public street right-of-ways.
In each case, the crossing design took into consideration vehicular traffic, line of sight, trail traffic, use patterns, road type and width, and other safety issues such as nearby schools.
These crossings have the following characteristics:
- Maximum traffic volumes of approximately 5,000 Average Daily Traffic (ADT) (1,000-1,500 peak hour).
- Maximum 85th percentile speeds 35 to 45 mi/h.
- A maximum street width of 60 ft (no median).
- A minimum sight distance of 100 feet in 25 mi/h zone, 200 feet in 35 mi/h zone, and 300 feet in 45 mi/h zone.
- Warning signs provided for motorists, and stop signs and slowing techniques (bollards/geometry) used on the trail approach.
- Vegetation and other obstacles cleared from motorist and trail-user sight lines.
- Three of the unprotected intersections (Johnson Creek Boulevard, Southeast Flavel, and Southeast 92nd Avenue) have median islands that provide a pedestrian refuge area and were added in anticipation of increases in traffic volumes on these streets.
Evaluation and Results
No crashes between a trail user and a motorist have been reported. The private driveway crossings typically serve large industrial complexes, and their access across the trail is permitted by the trail managing agency (the City of Portland). There have been no issues at these private driveway crossings.
Two of the three median refuge islands have landscaping. The landscaping has been subject to damage from automobiles.
Type 2: Route Users to Existing Intersection
The trail leads users very close to a major intersection at Southeast Linnwood and Johnson Creek Boulevard. This intersection went through a major redesign shortly after the Springwater Trail was built. Trail designers recognized the potential for improving safety by diverting trail users to the newly signalized crossing.
Major intersection at Southeast Linnwood and Johnson Creek Boulevard.
In addition, the former rail line crossed an existing intersection at Southeast Bell and Johnson Creek Boulevard at a diagonal through this intersection. The intersection was signalized prior to the construction of the trail. Trail users now utilize the existing signal, crossing each street one at a time.
The crossings have the following characteristics:
- Traffic signals and pedestrian activated signal button.
- Traffic volumes greater than 15,000 ADT.
- 85th percentile speeds greater than 45 mi/h.
- Street widths greater than 60 feet.
- A minimum line of sight of 100 feet in 25 mi/h zone, 200 feet in 35 mi/h zone, 300 feet in 45 mi/h zone.
- Warning signs provided for motorists, STOP signs and slowing techniques (bollards/geometry) used on the trail approach, and bollards that serve to minimize motorized vehicle access onto the trail.
- Vegetation and other obstacles cleared from motorists and trail user sight lines.
- ADA compliant curb ramps.
- A distance of trail to signalized intersection of less than 350 feet.
Evaluation and Results
Trail routed to Johnson Creek/Linwood signalized intersection. Trail users cross using crosswalks.
Type 3: New Signalized Crossings
There are four locationsSoutheast 82nd Ave, Southeast Foster Road, Southeast 122nd Ave, and Eastman Parkwayalong the Springwater Corridor where the trail crosses a major roadway of above 15,000 ADT. In all four cases, the crossing width was greater than 60 feet, the nearest intersection more than 350 feet away, and all had anticipated trail user volumes of greater than 100 per hour. Trail designers felt that new signalized crossings would be necessary to facilitate safe travel, and thus developed a signal warrant analysis that projected use through trail user numbers from the Burke Gilman Trail in Seattle, Washington, and user counts on a one-mile built portion of the Springwater Corridor in Gresham, Oregon. Each location was also analyzed for sight lines, impacts on traffic progression, timing with adjacent signals, capacity, and safety.
Trail users activate the signal as follows:
- Pedestrians: push button.
- Bicyclists: loop detector in pavement.
- Equestrians: push button mounted on pole at 8 foot height.
At Southeast 82nd, Southeast Foster Road and Southeast 122nd Avenue, the crossing includes a median island to reduce the crossing distance; signal activation in the median for those unable to cross the entire roadway in one movement; and advance warning signs for motorists.
Evaluation and Results
The signalized crossings have been effective, safe, and functional. Since their installation in 1995, there have been no reported collisions, with an estimated 500,000 annual users. Trail users note that although they must activate the signal and wait for a green light, motorists have gotten used to the signal and frequently stop before they get the red light. Traffic engineers report minimal interference with nearby signals, given the relatively distant spacing from the nearest signalized intersections.
Flat grade with sight lines at the 82nd Avenue and 122nd Avenue crossing.
Type 4: Grade-separated Crossings
There are five grade-separated crossings on the Springwater Corridor. These crossings consist of both over and undercrossings of roadways. Interstate 205, Highland Road/181st, and Telford Road were existing grade-separated crossings developed in response to the presence of the railroad.
Hogan Road and the 7th Street Bridge, both in the City of Gresham, are roadway improvement projects built after the trail was constructed. At both these roadway crossings, the roadway goes over the trail, and Johnson Creek is immediately adjacent to the trail. The Hogan Road crossing was implemented first, while the 7th Street Bridge project followed a few years later. Both grade-separated crossings were built in anticipation of high projected vehicle volumes and speed.
Bicyclist loop detector signal activation at one of the trail crossings.
Key characteristics of these undercrossings include:
- A minimum vertical clearance of eight feet.
- Placement of the trail at an elevation higher than the one year flood plain elevation of the creek.
- Maximum trail grade approaching the undercrossing of five percent.
- Alternative trail route leading up and over the bridge in the event the creek is in flooding stages.
- Lighting under the bridge.
- Rip-rap reinforced edge to the creek.
- Limited vertical clearance warning signs for trail users.
Motorist view of the trail crossing at 82nd Avenue and 122nd Avenue.
Hogan Road, having been the first of the two undercrossings to be constructed, had several shortcomings. Placement of the trail at the two-year flood plain elevation resulted in regular flooding and closure of the trail. With each flooding event, sediment from the creek was deposited on the trail, requiring regular clean-up. The approach to the undercrossing did not facilitate complete visibility through the undercrossing area, resulting in unsafe feelings among users along the approach. Lighting installed in the underpass area was vandalized, requiring the lights to be retrofitted with metal cages. To meet ADA grades on the trail approach, a switch back ramp was incorporated on the eastern side of the undercrossing approach. Turning radii used on this approach tend to be a bit tight for bicyclists' comfort. Today, about half the trail users opt to use the alternative, at-grade crossing route in lieu of the Hogan Road undercrossing, regardless of creek conditions.
Bicyclist view of the trail crossing at 82nd Avenue and 122nd Avenue.
These lessons learned were incorporated when the 7th Street Bridge project was proposed. Key characteristics of this undercrossing include:
- Placement of the trail at the 25-year flood plain elevation.
- Alignment of the trail approach to facilitate complete visibility of the undercrossing area.
- Installation of hose bib water connections to facilitate trail clean up in the event of a flood.
- Eight feet, nine inches of vertical clearance, instead of the minimum of eight feet.
- Use of vandal-resistant light fixtures.
- Setback of the bridge foundation abutment from the trail, resulting in a greater sense of openness under the bridge.
These improvements resulted in an undercrossing that has been well-received and equally well-used by the public.
Conclusions and Recommendations
Trail crossing designs tailored to the site characteristics (type of cross-street, traffic volumes, street width, traffic speeds, proximity to existing intersections, etc.) have resulted in well-functioning trail-roadway intersections with no reported safety problems to date. Experience with some undercrossings highlighted the importance of good design, including open approaches with good visibility and consideration of site environmental conditions.
President, Alta Planning + Design
Portland, OR 97214
3604 SE Lincoln St