Common Safety Problems and Solutions
* Disclaimer: These "problems and solutions" have been compiled from Traffic Safety Evaluation reports that were written to address specific locations and conditions in specific cities and counties. These solutions will not necessarily apply to your situation, nor are these necessarily solutions that could be appropriate and effective for your situation.
Problem: Frequent Collisions on a high volume arterial with many driveways.
- Reduce/combine driveways so that adjacent driveways are spaced at least 300 feet apart.
- Require deceleration lanes at driveways serving more than 100 vehicles per hour in the peak hours.
- Restrict left turn movements from driveways and minor streets onto major streets where there are opportunities to divert to a traffic signal or make a combination of right turn/U-turn maneuvers.
- Construct raised medians where none currently exist or in locations currently striped as two-way left turn lanes, to provide better access control, improve safety for left turning movements and provide a refuge area for pedestrians.
- Upgrade street lighting at locations where more than 40% of the collisions are occurring during hours of darkness.
Residences on a main street have full movement driveways leading directly onto the main street, causing conflicts with through traffic.
- Create a Design Review Board (DRB) that oversees new construction according to the design principles that reflect the historic nature of the city and requires developments to locate new driveways on the side streets and not directly on the main road. The DRB should also require sidewalks to be constructed as part of any new development/redevelopment project in the city. The cost would be borne by the developer.
Left turn movements into driveways that are too close to the intersection are contributing to collisions.
- As opportunities arise, the driveways closest to the intersection may be removed or restricted to right turn movements.
Collision Investigation and Reporting
Police officers frequently choose not to document complaint of pain collisions as injury collisions, opting to file them as Property Damage (PDO) instead.
This throws off Statewide Integrated Traffic Records System (SWITRS) raw data.
- Documenting complaint of pain injury level collisions as PDO is historically a field supervision issue.
Field supervisors should ensure that any level injury collision is documented as such.
Having a sergeant-level supervisor assigned to traffic address these types of issues best, as s/he can focus attention on the officer's field performance at collision scenes.
Collaterally assigning traffic duties to a patrol sergeant is another alternative, but less effective.
Cities with this problem may want to consider establishing a full or collateral Traffic Sergeant position.
- The Collision Investigation Manual (CIM) permits local agencies some latitude in the area of format given levels of injury.
Policies can be adjusted to accommodate levels of service and service call loads without necessitating the reduction of information gathered.
We recommend that cities modify their collision documentation policies to permit a report format on complaint of pain collisions, and investigation formats on collisions with more severe injury levels. This way the data maintains accuracy for design and deployment without requiring unrealistic performance levels from patrol.
Limited access to the agency's record system makes obtaining collision trend analysis or citation issuance historical records difficult.
- We suggest the development of a small, easily prepared and understood monthly traffic report with clear direction for police department personnel. It should reflect trends on high collision intersections, segments and their PCF's, enforcement percentage contrast, along with the calculation of the department's traffic enforcement index. The report should include the prior month's or quarter's goals and progress and some useful year-to-date data.
- To produce these reports and queries, most records systems should take only minutes, but yield specifics essential to effective deployment and focus areas. This software should avail useful, accessible data to traffic supervisors beyond just establishing goals and progress.
Uncontrolled crosswalk with minimal treatments at offset intersection on a multi-lane, higher speed road carrying in excess of 15,000 vehicles per day.
- Upgrade the crosswalk to provide high visibility markings, a pedestrian refuge island, and fluorescent yellow green pedestrian crossing signs that are in compliance with the California Manual on Uniform Traffic Control Devices (MUTCD). Consider adding pedestrian-activated flashing beacons.
Marked crosswalks that are heavily used by students and other pedestrians are marked with minimal treatments.
- Restripe crosswalks using high visibility ladder type markings.
- Install pedestrian crossing signs using fluorescent yellow green signs.
Double post pedestrian crossing signs at each end of the crosswalk.
- Install pedestrian warning signs with a "next 1 mile" plaque using the fluorescent yellow green signs facing approaching traffic.
- Install "Sharks Teeth" type yield markings in advance of marked crosswalks.
- Install curb extensions The extensions reduce the width of the street that pedestrians have to cross while providing a narrowing effect of the roadway to drivers which encourages them to drive slower.
- Require all curb return radii to be at least 25 feet with wheelchair ramps whenever intersections are improved by new development or redevelopment projects.
The majority of collisions involving pedestrians occur when pedestrians themselves have entered a roadway outside of a marked or unmarked crosswalk.
- Establish traffic goal setting protocols for patrol deployment.
- Consider conducting pedestrian and bicyclist-focused enforcement plans in high collision corridors to reduce injury collisions and bring media attention to the compliance problem. Consider inviting the media to observe the enforcement.
- The city's police department may work in concert with Engineering towards a common goal of collision reduction, especially in the areas where pedestrian and bicycle collisions occur.
An Example of Curb Extensions
- Install in-roadway flashing yellow LED raised pavement markings along crosswalk edges. Install flashing yellow LEDs in the pedestrian crossing signs at the crosswalks. These are activated by passive pedestrian detectors or pushbuttons. Warning: Visibility in bright sunlight can be difficult.
- Install pedestrian refuge islands at the marked and unmarked crosswalk locations. These islands could also be part of a median for providing left turn lanes at intersections.
Pedestrian Refuge Island
- Install "Smart" crosswalks with overhead flashing beacons activated by passive pedestrian detectors or pushbuttons. This treatment could include the in-pavement flashing lights as an additional enhancement. However, the LEDs in the pedestrian crossing signs and the overhead pedestrian activated flashing beacons are much more visible to drivers approaching the crosswalks.
Many pedestrians cross outside a crosswalk on a street with heavy traffic flow and 6 traffic lanes.
The street has a raised 3-foot wide center divider median, which is used as a safety zone by pedestrians and allows them to cross looking for gaps in traffic from both directions.
This causes a disruption in the traffic flow as drivers are distracted and slow down for pedestrians waiting on the center median.
The city installed an international "No Pedestrian Crossing" sign and a regulatory (black and white) "use Crosswalk" sign on a light standard on the center divider.
However, pedestrians continue to cross outside the crosswalk at that location.
- Consider erecting a physical barrier in the center divider at that location to discourage pedestrians from crossing mid-block. This could be accomplished with a low 2 to 3 foot wall of slump stone or similar blocks which would not detract from the aesthetic design of the center divider.
On a street with much pedestrian traffic and two driveways leading to large corporations, many pedestrians cross despite the lack of a marked crosswalk.
There is a raised center median with a left turn pocket in each direction. The pedestrians crossing at this location are virtually all adults, the nearest marked crosswalk is several hundred feet away, there is a raised center median so pedestrians can cross one direction of travel at a time, and the signals at the arterials on either side provide breaks in the traffic.
- The location would benefit from a marked crosswalk. In addition, a marked crosswalk would channel the pedestrians to a single location whereas now they are crossing in various locations. The crosswalk should be accompanied by the standard Caltrans warning signs: W54- the pedestrian crosswalk warning sign and the W54A - the advance pedestrian warning sign, for both directions of travel.
- The decision of where to place the marked crosswalk could be based on sight distance, the width of the center median and the available queuing space on the median island, and the right turn volumes exiting the driveways, (the side with the fewest right turns is preferred since right turning motorists are focused on looking to the left to find a gap in traffic, and sometimes fail to check for pedestrians to the right). Total travel lanes and traffic volumes at both candidate locations should also be evaluated, but it is likely they are similar for both sides. In addition to the marked crosswalks, the approach pathways to the marked crosswalk on each side of the street should be made more attractive.
Hit and Run
A substantial frequency of hit and runs.
- An effective means for addressing hit and runs is to focus on DUI enforcement, driver's license violations, vehicle impound practice and financial responsibility enforcement.
- A "master DUI log" could be established and maintained for identifying training needs in the area of DUI detection.
The "master" log would account for all arrests for DUI regardless of outcome.
Those supervisors responsible for training would be able to quickly identify the patrol officers need for refresher training before such a problem worsened.
- Consider the acquisition and installation of "Rat Boxes" at high red light running intersections to facilitate more effective enforcement.
An intersection has very heavy right turn movements from a busy street onto a main street.
- Possibly convert 8" signal indications to 12" signal indications.
- Restripe approaches to the intersection to provide exclusive right turn lanes and through lanes.
- Provide right turn overlap phases for busy street approaches to the intersection; this requires restriction of U-Turns on the main street.
Overhead utility lines partially obscure signal head indications
- Relocate overhead utility wiring so that it does not obscure the visibility of the signal indications.
- Convert all 8" signal indications to 12" signal indications.
At a 4-legged intersection controlled by a fixed time signal with no separate left turn phases, a high number of crashes occur between left turning and oncoming vehicles.
- The traffic signal should be converted to fully actuated operation with fully protected left turn phases on all approaches.
Signal was constructed over 15 years ago. There is only one signal head on the mast-arm for three approaching lanes; the current standard calls for two heads. The left turn signals are in the median islands and the current standard requires placement of left turn signals on the mast-arms.
- The traffic signal equipment at this location may be upgraded to provide an additional head on the mast-arm for through traffic on the approaches.
The left turn signals should also be relocated onto the mast-arms.
Rear-end collisions are occurring between vehicles turning left from street A.
There are two through lanes striped in each direction with a double yellow centerline.
Although parking lanes are provided on both sides of street A, their usage appears to be low.
- We suggest removing parking on both sides of street A to provide at least 100 foot turn lanes for left turn traffic on street A.
Conflicts involving vehicles maneuvering in and out of on-street parking are the major source of crashes on a downtown street.
- Reduce the amount of or change the configuration of on-street parking.
A high number of collisions occur when drivers are backing out of an angled parking spot onto a roadway on a section of a main road where angled parking is provided.
- Consider converting traditional front-in angled parking to require back-in maneuvers.
Example of Back-in Diagonal Parking
A particular main street is not oriented toward the needs of a downtown street, nor does it keep with the character of the city.
Among the missing aspects are better access control, creation of downtown ambiance and treatments designed to create an atmosphere of community enhancement.
- Construct a median in the center of the main street that will provide: better access control, a refuge area for pedestrians crossing the street, and a place to plant trees. Tree canopies provide a traffic calming effect which will help reduce crash frequencies.
Red Light Running
There is a high percentage of red light running collisions at an intersection.
- Install red light indicators, AKA "rat boxes." This 2"-3" red LED array is hardwired to the back of a signal head and is then pointed to a position of advantage for the officer. These inexpensive traffic signal accessories ($150 - $200) enable a traffic enforcement officer to observe the condition of the signal from downstream or side-street position and to pursue red-light violators without endangering themselves or other road users. Officers can keep track of the signal from a distance, usually on the other side of the intersection. This allows officers to safely stop the red light runner without the risk of crossing the intersection against the red light. More information on this device can be found here.
Traffic congestion and safety concerns around an elementary school during drop-off and pick-up times.
- Additional passenger loading zones.
This can be done by reducing full-time parking areas adjacent to schools.
Use white paint and stencils to mark the loading zone; the paint is more effective than signage.
- Signal timing modifications. Provide leading pedestrian "walk" intervals to allow crossing guards to establish right-of-way for students crossing at busy intersections.
If the leading "walk" intervals are not sufficient for pedestrians to establish right-of-way, provide protected/permissive left turn phase.
- In-roadway pedestrian warning signs at uncontrolled crosswalks. Consider installing other treatments to improve pedestrian safety at intersections without traffic controls.
Vehicles making right turns on red make it difficult for school crossing guard to cross students.
- Restrict right turns on red to reduce conflicts with school age pedestrians when the crossing guard is present.
Signs and Markings
Visibility of stop sign obscured by a large vehicle that regularly parks in front of the sign.
- Upgrade stop signs to 36".
- Restrict parking on the approach to the sign to prevent parked vehicles from obstructing the visibility of the stop sign.
Visibility of stop sign obscured by vegetation.
- Install Driver Speed Feedback Signs at various locations throughout the city.
A small city's main street follows 15 miles of uninterrupted high speed traffic flow conditions.
Drivers are traveling in excess of 85 mph before entering the city, and are continuing through the city with excessive speed.
Drivers typically slow to 40 mph but not to the posted speed limit of 25 mph.
- Paint 12" wide transverse lines across travel lanes that become more closely spaced as they approach the city. This gives drivers the impression that they are traveling faster than they actually are so that they will slow down.
- Install Radar Enforcement Signs depicting a motorcycle officer holding a radar gun.
- Install speed limit signs in more prominent locations closer to the travel lanes to make them more visible to drivers.
- Install driver feedback speed monitoring signs.
- Install a monument or overhead signs to notify drivers that they are entering the city, where there is an increased level of turning movements and pedestrian activity and to slow down. Such signs have been installed in other communities where they provide a strong visual impact as drivers approach the town limits.
Vehicles speed on an uncontrolled state route that runs through a city.
- If CHP field officers are concerned about high collision locations outside of the city, "photo speed detection" is an option local community leaders may wish to have the CHP explore. Although use of photo speed detection in California has not yet received the same level of acceptance as photo red light programs, such an area could serve as a test area. Community leaders could request the CHP conduct a photo speed detection "pilot project" in town in order to help control speed, traffic flow and future collision levels. The idea of using photo speed detection would not be to supplant the role of the CHP officer, but rather to enhance their effectiveness and allow them to focus on other violations. Based on our experience with photo red-light enforcement systems, a photo speed detection system would likely serve as an outstanding deterrent to speeders and reduce collisions accordingly.
- Install a traffic signal with a photo red-light system.
- Build a truck bypass around the city.
Speeding in a downtown area.
- Require development projects to plant appropriate types of trees in sidewalk tree wells to enhance the appearance of the city and provide tree canopies over the main street which may provide a traffic calming effect. The trees should be of the types that do not have roots that would damage the sidewalk over a period of time.
High volume of through traffic on a one-way residential street that connects a main street to the parking lot of a large shopping center.
- To address the volume of traffic, an island could be constructed in the center of the street to prevent traffic entering as a cut-through route to and from the shopping center.
Example of an Island Retrofitted to Restrict Cut-Through Movement
The location of a transit stop on a 4-lane main street just before an intersection with a busy 2-lane street with a left turn lane causes buses to swing wide to complete a right turn onto the busy street. This creates potential conflicts with traffic in the left turn lane.
- Modify the location of the transit stop on the main street so that buses can turn more easily onto the busy street.
- Re-stripe the busy street as it approaches the main street so that the exit lane is wide enough to allow buses to turn onto the busy street if there is a bus or other large vehicle in the left turn lane.