Proposed Solutions

1. Semi-diverters on 17^th and 18^th to encourage clockwise circulation pattern around the school. The effect would be predominant northbound traffic on 17^th and southbound traffic on 18^th in the two-block region between Mason and Failing Street. And modify parking restrictions on the west side of 18th between Mason and Failing.
2. Speed bumps on 17^th and 18^th, between Mason and Failing to deal with speeding, which was expected to increase with the clockwise circulation and corresponding reduction in opposing traffic.
3. Remove an older semi-diverter at 17^th and Shaver that obscured pedestrians crossing the street and add a marked school crosswalk.
4. Add pedestrian refuge islands at the school crosswalks on Prescott and Fremont at 18^th Avenue.

Public Involvement

 
Photo 1. NE 17^th at Mason test diverter, looking south.

Testing

Temporary semi-diverters were installed and tested on SE 17^th Avenue and SE 18^th Avenue. Testing is required to measure the impact of the devices on adjacent residential streets. There were concerns expressed during neighborhood meetings that the modification of the traffic would force drivers to shift to adjacent streets, increasing the traffic volume there to unacceptable levels. There was also concern that the devices would not be effective in modifying the behavior of parents and guardians to encourage them to shift to a clockwise driving pattern around the school. Not only would they not comply with the change in the traffic pattern, they were also expected to be speeding, the argument went.

 

The petition-to-test area included NE 17th and 18th, the project streets, and all properties on intersecting streets within approximately a block (or about 200 feet) of the project streets. A majority of households within the petition-to-test area are required to sign the petition for the test to proceed. Each household, including renters and businesses, are entitled to one signature. Non-resident property owners are not required to sign the petition-to-test. A breakdown of the result follows:

 

Category	Number	Percent
Number of signatures in Support	28	70.0%
Number of signatures Not in Support	3	7.5%
Number of Maybe	1	2.5%
No Preference/No Action	8	20.0%
Total	40	100.0%

 

Test diverters were installed for three months before follow-up data was collected. After the data was analyzed, significant speeding did not occur on 17^th or 18^th Avenue. As a result, speed bumps were eliminated from the final design. In February 1998, advisory ballots were mailed to residents and non-resident property owners on the affected streets. To ensure that a sufficient number of the affected residents expressed their opinion regarding the construction of permanent structures, committee members circulated a second ballot. Out of 41 affected (eligible) properties, 30 responses were obtained and 22 or 73%, favored permanent construction.

Construction

All temporary devices were left in place until permanent construction began. Nutter Underground Utilities Company completed permanent construction in September 1998.

Performance

NE 17^th Avenue – Failing to Mason

NE 17^th Avenue is designated a Local Service street in Portland’s traffic street classification system. The purpose of the street is to provide access from private property to higher classified streets. The street is 36 feet wide with curb and sidewalk on both sides. The street is straight and level at the south end of the school, but north of Shaver begins climbing a moderate hill.

 

Vehicle Speed and Volume

 

Table one shows the average 85th percentile vehicle speed before the project was 26 mph south of Shaver and 28 mph north of Shaver. Since construction the average 85th percentile speeds are 28 and 26 mph, respectively.

 

Table 1. Vehicle Speed on NE 17^th Avenue

 

	Before			Test				After
17th S/Shaver	NB	SB	Avg.	NB	SB	Avg.	%chng	NB	SB	Avg.	%chng
6/9/97	26	27	26.5
12/17/97				28	27	27.5	3.8%
3/8/99								27	28	27.5	3.8%
17th N/Shaver
6/4/97	28	28	28
12/9/97				27	27	27	-3.6%
3/8/99								25	27	26	-7.1%

 

Avg. = Average; NB = northbound; SB = southbound; and %chng = percent change from first count.

 

Traffic volumes measured before construction averaged 330 vehicles per day (vpd). After construction volumes averaged 360 vpd. The table 2 shows how the directional split has changed to predominantly northbound, especially between Failing and Mason, as desired.

 

Table 2 – Volume Changes NE 17^th Avenue, Fremont to Prescott

 

	Before	%		After	%
NE 17th N/Fremont Northbound	169	49%		274	65%
Southbound	179	51%		147	35%
Total	348			421
NE 17th N/Failing Northbound	178	51%		319	92%
Southbound	170	49%		28	8%
Total	348			347
NE 17th S/Mason Northbound	133	43%		336	92%
Southbound	175	57%		29	8%
Total	308			365
NE 17th S/Prescott Northbound	137	41%		171	64%
Southbound	198	59%		97	36%
Total	335			268

 

NE 18^th Avenue – Mason to Failing

 

NE 18^th Avenue is designated a Local Service street in Portland’s traffic street classification system. The purpose of the street is to provide access from private property to higher classified streets. The street is 28 feet wide with curb and sidewalk on both sides. The street is straight and level at the south end of the school, but at Shaver begins climbing uphill.

 

Vehicle Speed and Volume

 

Table three shows the average 85th percentile vehicle speed before the project was 28 mph south of Shaver and 25 mph north of Shaver. Since construction the average 85th percentile speeds are 23 and 26 mph, respectively.

 

Table 3. Vehicle Speeds on NE 18^th Avenue

 

	Before			Test				After
18th S/Shaver	NB	SB	Avg.	NB	SB	Avg.	%chng	NB	SB	Avg.	%chng
12/17/96	28	28	28
12/8/97				26	26	26	-7.1%
3/9/99								21	24	22.5	-19.6%
18th N/Shaver
5/29/97	27	24	25.5
12/9/97				27	25	26	2.0%
3/8/99								27	24	25.5	0.0%

 

Avg. = Average; NB = northbound; SB = southbound; and %chng = percent change from first count.

 

Traffic volumes measured before construction averaged 320 vehicles per day (vpd). After construction volumes averaged 360 vpd. The table 4 shows how the directional split has changed to predominantly southbound, especially between Failing and Mason, as desired.

 

Table 4 – Volume Changes NE 18^th Avenue, Fremont to Prescott

 

	Before	%		After	%
NE 18th N/Fremont Northbound	294	46%		129	26%
Southbound	342	54%		370	72%
Total	636			499
NE 18th N/Failing Northbound	325	46%		16	3%
Southbound	382	54%		576	97%
Total	707			592
NE 18th S/Mason Northbound	243	46%		22	4%
Southbound	287	54%		475	96%
Total	530			497
NE 18th S/Prescott Northbound	233	43%		69	18%
Southbound	309	57%		307	82%
Total	542			376

 

Crosswalk on Prescott at 18^th
Prescott Street is designated a Neighborhood Collector street in Portland’s traffic street classification system. The purpose of the street is to provide access from lower classified Local Service streets to higher classified streets. The street is 28 feet wide with curb and sidewalk on both sides. The street is straight and level with parking on one side only.

 

Graph 1

 

Vehicle Speeds

 

As the graph shows, have been reduced from about 36 mph into the range of 30 to 35 mphs. The average 85th percentile vehicle speed at the crosswalk before the project was 36 mph. Since construction the average 85th percentile speed is 33 mph in the 30-mph zone (except when children are present). Speed reduction, though desirable, is not a predictable goal when using pedestrian refuge islands.

 

Traffic Volume

 

The traffic volume measured before construction was 6200 vehicles per day (vpd). After construction volumes averaged 6000 vpd. The 200-vpd difference is within the range of normal daily fluctuations.

 

Crosswalk on Fremont at 18^th

Fremont Street is designated a Neighborhood Collector street in Portland’s traffic street classification system. The purpose of the street is to provide access from lower classified Local Service District Collector streets to higher classified streets. The street is 36 feet wide with curb, sidewalk, and parking on both sides. The street is straight with a gentle slope.

 

Graph 2

 

Vehicle Speeds

 

As graph two shows vehicle speeds have been reduced from about 35 mph into the range of 30 to 32 mph. The average 85th percentile vehicle speed at the crosswalk before the project was 35 mph. Since construction the average 85th percentile speed is 30 mph in the 30-mph zone (except when children are present). Speed reduction, though desirable, is not a predictable goal when using pedestrian refuge islands.

 

Traffic Volume

 

The traffic volume measured before construction was 10480 vehicles per day (vpd). After construction volumes averaged 10600 vpd. The 200-vpd difference is within the range of normal daily fluctuations.

 

Neighborhood Traffic Volumes

 

Because traffic diverters were installed, data was collected from several streets that are parallel to the streets around Sabin Elementary. This data collection provides a better picture of what effect diversion has on the general neighborhood. Map three (next page) displays the before and after traffic volumes measured around the school.

 

Map 3. Traffic Volume Measurements

 

 

Except for two street segments, no post-project traffic volumes exceeded allowable volume thresholds. NE Shaver, east of 18^th Avenue, and NE 19^th Avenue will be measured again to assess the nature of the increase.

Summary

The Sabin Elementary School Safety Project has succeeded in meeting its primary goals as follows:

 

Minimize traffic congestion around school: Traffic flow around the school has been changed from a two-way pattern to a predominantly clock-wise pattern. This change in traffic patterns permitted restoration of parking where it was once prohibited. The potential for two-way traffic conflict, where space exists for only one vehicle, has been significantly reduced.

 

Decrease speeding on 17th and 18th: As a result of testing the diverters, it was determined that speed did not increase as feared. Speed bumps were eliminated from the project. Vehicle speed remains similar to pre-project measurements.

 

Improve visibility at 17^th and Shaver: The Bureau of Environmental Services removed an older semi-diverter that obscured pedestrian visibility. The new diverter does not have the same intensity of landscaping that was the cause of the visibility problems.

 

Improve crossing safety on Prescott and Fremont at 18^th: Pedestrian refuge islands were installed to increase crossing opportunities. Traffic speeds at the devices have reduced slightly.

School Comments

The principal discussed the project with several adjacent residents. They expressed agreement that the new traffic pattern has reduced the congestion and speed at the opening and closing time of school. Parking has improved. And, conflicts between buses and automobile traffic are reduced.

Conclusions

Traffic Calming at Sabin Elementary has enhanced street safety and livability.