Work Zone Mobility and Safety Program
Photo collage: temporary lane closure, road marking installation, cone with mounted warning light, and drum separated work zones.
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Text from 'Highway 125 Night Work' PowerPoint Presentation

Slide 1

Highway 125 Night Work

Making Work Zones Work Better Workshop
Gerard Kennedy, P.Eng.
Nova Scotia Department of Transportation & Public Works

Slide 2

Night Work = Safety Concerns

Speaker Notes: Construction personnel who work at night or in low light conditions are 2 1/2 times more likely to be seriously injured or killed as a result of being struck by motorists or piece of mobile equipment.

That is why it was so important to develop a special network specification for our Highway 125 project.

Slides 3-4

Hwy 125 Night Work

  • Project Background
  • Specification Development
  • Traffic Management

Speaker Notes: This presentation will focus on three aspects of the project.

  1. I'm going to speak a little about project background
  2. I'm going to go into detail on the development of the night work specification.
  3. I'll then talk about our traffic management plan for the project.

Slide 5

Province of Nova Scotia

Speaker Notes: Nova Scotia is one of Canada's provinces and is located on the Atlantic Coast , north-east of the state of Maine.

Slide 6

Highway 125

Speaker Notes: Highway 125 circumnavigates Sydney Harbour and is the main arterial route linking most of the communities in the Cape Breton industrial area. It also serves as the primary artery to connect these communities to the Trans-Canada highway.

The section we worked on is just outside the city of Sydney and is commonly known as the Sydney bypass.

Slide 7

Highway 125

Speaker Notes: The section under contract lies outside the city of Sydney and has four interchanges. Of particular interest is the close proximity of the Cape Breton Regional Hospital to exit 8.

Let's look at a few statistics for the project. This section is a 100 series two-lane two-way highway. The total length of the project including ramps was 11.2 kilometers. Including cold planing of 110,000 square meters, 33,000 tons of asphalt paving including polymer modified asphalt in the top lift and about 3.5 kilometers of guardrail.

Slide 8

Hwy 125 - Traffic Volumes

  • AADT = 21,000 veh/day
  • ADT (Summer) = 25,000 veh/day
  • Daytime Hourly = 1000 to 2200 veh/hr
  • Peak Flow > 2300 veh/hr

Speaker Notes: Let's look at the traffic volumes on Highway 125.

The average annual daily traffic is about 21,000 vehicles per day.

During the summer daily traffic increases to about 25,000 vehicles per day.

Daytime hourly volumes range between 1000 and 2200 vehicles per hour.

During the peak afternoon rush-hour, traffic peak flow can exceed 2300 vehicles per hour. That means that a vehicle passes a point on this section of Highway 125 on average everyone one and a half seconds.

It was very obvious that to avoid excessive delays it would be necessary to work at night.

Slide 9

Hwy 125 Night Work

  • Specification Development

Speaker Notes: Let's have a detailed look at the development of the night work specification for the project.

Slide 10

Information Gathering

Speaker Notes: I gathered information from throughout North America to develop a night work specification for the project. I contacted most state and provincial agencies as well as researchers at the transportation research board who at the time had a major night work research project under way.

Slide 11

Images of Existing Nighttime Construction Guidance Translated Into Specifications

Speaker Notes: I gathered all kinds of information from these sources and "boiled" them down into a specification and that was practical to implement in the province of Nova Scotia.

Slide 12

Night Work Specification

  • Work periods
  • Planning
  • Training
  • Signing
  • Channelization Devices
  • Traffic Control Persons
  • Workers
  • Work Vehicles
  • Lighting
  • Site Maintenance

Speaker Notes: Let's look at the main areas covered under the night work specification. Work periods, planning by the contractor before work began, training of all personnel who would be on the site, special signing requirements. Requirements for channelization devices, traffic control persons, workers and work vehicles. Maintenance of the site.

Slide 13

Night Work Specification

  • Work periods

I'll explain how the work periods were determined.

Slide 14

Hwy 125 - Hourly Traffic Volume - Aug/02

Speaker Notes: If we plot the hourly distribution of traffic for Monday on Highway 125 - there's a peak early in the morning, fairly high traffic volume through the day and another peak at the quitting time. Then a slow decrease in the evening.

From the plots for the remainder of the weekdays we can see that they basically follow the same distribution; however on Saturday and Sunday the distributions are quite different so, when determining the hours of work , we have to take those special days into account.

Slide 15

Hwy 125 - 750 Veh/Hr Restriction

Speaker Notes: Practical experience and information from our traffic division indicated that the capacity of a 1.5 kilometer work zone is somewhere in the order of 700 to 800 vehicles per hour. So if we draw a line at 750 vehicles per hour we can see that the cut off points would be at 5:30 AM and 9 PM - in other words we couldn't allow full or partial lane closures during this period. That only allows us 8.5 hours of working time, which is fairly inefficient for a contractor.

Slide 16

Hwy 125 - 1000 Veh/Hr Restriction

Speaker Notes: By making an assumption that by implementing an aggressive traffic management plan we would be able to divert somewhere between 20 and 30 percent of the vehicles arriving at the worksite to alternate routes we can use 1000 vehicles per hour and as the cut off. This meant that the no lane closures would be allowed during the period from 6 AM to 7 PM on weekdays. This allowed for 11 hours of work during the night for the contractor, which was more in line with the typical roadwork contractor schedule. The cut-off times were adjusted to meet the changing distributions for Saturday and Sunday - this allowed even more than 11 hours of work on those days.

Slide 17

Night Work Specification

  • Planning

The night work specification required the contractor to carry out very detailed planning before any work could begin on the project.

Slide 18

Nighttime Work Plan

  • Traffic control
  • Emergency vehicles
  • Temporary markings
  • Lighting design
  • PPE requirements
  • Training plans
  • Noise reduction

Speaker Notes: Our Contractor - Municipal Ready Mix of Sydney - early in the project submitted a night work plan which met the requirements of the specification.

The night work plan included such things as details of their traffic control procedures, plans for the passage of emergency vehicles and how they intended to apply temporary markings during night operations. Lighting design was a major part of their submission . The plan also set out the personal protective equipment that would be required on the jobsite and details on how they would train their employees. There were also some strategies for reduction of noise when they were working near residential areas.

Slide 19

Lighting Design

Speaker Notes: Municipal hired an electrical engineering consultant to develop their lighting design. The specification required that the designer have experience in both the areas of the vision and photometrics. Municipal would have provided information on their proposed lighting units to this electrical engineering company, who in turn would obtain photometric data from the manufacturer. They would then plug the information into their modeling software and be able to predict the spacing and geometric layout of the lights which would be required to meet the end illumination requirements of the contract. The lighting plan included details of the tower layout. The little black numbers shown are predicted illumination values on the roadway.

Slides 20-21

Lighting Design

Speaker Notes: The plan also includes geometric information for aiming the lamps and details for layout of the lighting at traffic control person stations.

Slide 22

Night Work Specification

  • Training

Speaker Notes: All workers had to be specifically trained in night work operations.

Slide 23

Night Work Training

  • Night work hazards
  • Vision
  • Visibility
  • Reflective Materials
  • PPE & Site Requirements

Speaker Notes: Municipal’s safety consultant developed a training program for the workers to be taken before work began. The training program included such topics as night work hazards, vision and visibility concepts, the importance of reflective materials and the Personal Protective Equipment requirements for the site. Once and employee had completed the training he was issued with a card certificate.

Slide 24

Photo of Training Session

Speaker Notes: This is a photograph of a training session under way. Municipal offered to extend their training to Department employees so we see both contractor and government employees in this photo.

Slide 25

Night Work Training - Site

Speaker Notes: We tried to train as many people as possible before work began in the formal training sessions. However there were workers and Department staff who occasionally worked on the site who had not been able to take the formal training. These people were trained on the site before they were allowed to start working. The training was in the form of a "toolbox" talk in which the main areas of the formal training were covered. They were also issued additional reflective materials and personal protective equipment at that time to meet the site requirements.

Slide 26

Night Work Specification

  • Signing

Speaker Notes: Signing is especially important at night to because of the lack of visual cues that are available during the daytime. It is important that motorists take notice of the signs because night work is not as expected as road work during the day.

Slide 27

Photo of Sign with Detail of Sheeting

Speaker Notes: All signing on the project had to be made from ASTM Type III sheeting to ensure high retroreflectivity.

Slide 28

Photo of Sign, 1.5 Meters Above Shoulder

Speaker Notes: All signs had to be mounted so that the bottom of the sign was at least 1.5 meters above the shoulder elevation. There were a number of reasons for this requirement.

First, raising the sign helped to avoid a common situation with shoulder height signs. Often shoulder height signs are blocked by vehicles ahead in a traffic stream. Mounting the signs higher helped to minimize this problem.

Slide 29

Photo of Work Zone at Night

Speaker Notes: This slide demonstrates the importance of work zone approach signing at night. Drivers don’t have many of the visual cues often available during the day when approaching a work zone, so the signs are very important to alert drivers to the unusual condition of night work.

Slide 30

Photo of Flashing Light Unit

Speaker Notes: There was a requirement that flashing light units be erected so that they provided the maximum distance possible for observation by the motorist.

Slide 31

Night Work Specification

  • Channelization Devices

Speaker Notes: There were special requirements for channelization devices under the specification.

Slide 32

Photo of Two Traffic Cones

Speaker Notes: The cone on the right is the cone currently required for night operations under the Nova Scotia Temporary Traffic Control Manual. It is 450mm high with one strip of reflective material.

The cone on the left is the type required under the night work specification for this project. It is 760 mm high with two bands of reflective material. The larger cone with more reflective material was preferable so that we could create more of a "wall" effect with our channelization devices and so that they be more visible.

Slide 33

Photo of Barrels in a Taper Area at Night

Slide 34

Photo of Lane Closure at Night

Speaker Notes: This slide shows cones being used to delineate a lane closure at night. The maximum spacing permitted on this project was 12 meters, which is less than the spacing, which would have been allowed on this class of highway during the day. The idea was to create a "wall" effect to try to prevent penetration of the work zone by motorists.

Slide 35

Photo of Closed Lane at Night

Speaker Notes: There was also a requirement that 2 barrels be placed transversely across a closed lane at 250-meter intervals. The idea was to alert an errant driver that he was in the wrong lane.

Slide 36

Night Work Specification

  • Traffic Control Persons

Speaker Notes: There were special requirements for traffic control persons in the specification.

Slide 37

Photos of Light Towers (Day and Night)

Speaker Notes: Municipal ready mix fabricated telescopic light towers for erection at the traffic control stations. Two 1000 watt halogen lamps were used; a portable generator powered them. Municipal was able to attain Level 3 lighting at these stations, which helped the traffic control person to stand out from the site lighting in the background.

Slide 38

Photo of Traffic Control Person With Stop Sign Standing 5 Meters From Light Tower

Speaker Notes: Early in the project we noticed that if the traffic control person stood directly beneath the light, he would often stand in his own shadow which tended to "dull" his bright clothing.

We found that placing the traffic control person about 5 meters from the light tower with the light cast on him allowed his bright clothing to stand out. The lights were positioned on the shoulder and aimed so that they were not blinding to the traffic control person.

Slide 39

Photo of Traffic Control Person Holding Stop Sign and Flashlight With Red Coned Cover

Speaker Notes: Traffic control persons met the requirements already set out in the Nova Scotia Temporary Traffic Control Manual, which requires white coveralls, reflective vest and reflective armbands. It also requires the use of a flashlight with a red coned cover. This proved to be very effective for conveying instructions to motorists.

To meet our site requirements the traffic control persons also had extra reflective material added to their hard hat. They were also in radio communication with the other traffic control persons and the pilot vehicle operator.

Slide 40

Night Work Specification

  • Workers

Speaker Notes: The specification contained special requirements for all workers on the site.

Slide 41

Photo of Workers Preparing a Traverse Joint

Speaker Notes: This is a photo of Municipal’s workers preparing a transverse joint. You can clearly see the reflective materials they are wearing.

The specification required all workers to wear reflective safety vests, to add reflective materials to their hard hats and to add other reflective materials so that they were visible under the full range of body motions.

Slide 42

Photo of a Hard Hat with Reflective Material

Speaker Notes: Hard hats had to have reflective material added to them so that they were visible from all directions.

Slide 43

Photo of "Standard" Vest

Speaker Notes: This is the standard safety vest most commonly used in Nova Scotia. It is made from a mesh fabric with a yellow plastic reflective material on the front and back. This was the type of vest worn by Municipal’s workers.

Slide 44

Photo of Reflective Material

Speaker Notes: Municipal met the requirement of providing additional reflective material so that workers were visible under the full range of body motions by issuing all their employees with reflective armbands.

Slide 45

Photo of Workers Wearing Reflective Material

Speaker Notes: After the contract had been awarded I became aware of a new CSA standard that was under development for high visibility garments. I was able to get a draft copy of the final standard and had vests for my own staff fabricated to those standards. This is how Department staff met the requirement for additional reflective materials.

I’m going to take a few minutes to discuss high-visibility garments since they will very likely be required on future night work projects and eventually will become the standard in Canada for both night and day.

Slides 46-47

Photos of High-Visibility Vests

Speaker Notes: A high visibility vest has two main components.

The fabric "background" component is made from a solid florescent colour material. The colour allows the wearer to stand out from his surroundings during daylight and low light conditions such as dawn, dusk and in fog. The fabric is solid rather than the mesh currently used. The mesh vests tend to be "dulled" if a dark garment is worn under them.

The fabric in the high visibility vest is also continuous around the torso so that it provides side visibility. The current vests provide no improved side visibility.

The reflective material provides visibility at night. The Hi-Viz vests require that the reflective material meet certain performance standards and minimum areas. There is also a torso bar on the vest to provide side visibility.

Slide 48

Photo of Workers at Night in Dark

[Only the yellow and silver trim is visible.]

Speaker Notes: This slide demonstrates why reflective materials are so important at night. If employees leave the lighted area it is the only thing that provides visibility for them.

In this photo you see both Department and Municipal employees standing outside of the lighted work site. Note the difference in performance of the yellow trim and the silver trim on two of the workers.

Slide 49

Night Work Specification

  • Work Vehicles

Speaker Notes: Work vehicles had to meet special requirements under the specification.

Slide 50

Photo of Haul Truck at Night With Sign "Work Vehicle Do Not Follow"

Speaker Notes: All haul trucks had to post a sign on the tailgate "Work Vehicle Do Not Follow". The idea was to prevent what can be a very common occurrence even during day operations. Often the traffic stream following a haul truck will follow the truck when he pulls into the closed lane. We wanted to try to prevent penetration of the lane closure by motorists because of the added hazards of working at night. This sign proved to be very effective at preventing that problem.

Slide 51

Photo of Same Haul Truck as Slide 50, with Less Light

Speaker Notes: This slide shows the reflective properties of the sign. You can also see reflective material, which was added to outline the truck box as required in the specification.

Slide 52

Photo of Truck at Night in With Reflective Material

Speaker Notes: In this slide we see the reflective material, which has been added to the sides of the truck box.

We also required that all vehicles be outfitted with a rotating incandescent light. Strobe lights were not permitted. This was based on a suggestion from a TRB study, which noted that strobe lights do not give good rate of closure information to approaching motorists.

Slide 53

Photo of Strobe and Incandescent Lights

There is a significant difference between the performance of strobes and incandescent lights. There seems to be some "residual" light remaining even when the reflector on the incandescent light is facing away from the observer so you have "constant target" as you are approaching. The strobe however does not provide a "constant target."

Slide 54

Night Work Specification

  • Lighting

Speaker Notes: Lighting was a major component of the night work specification.

Slide 55

Lighting Levels

  • Level 1 : General Site Lighting - min 59 lux (Safety)
  • Level 2 : Behind the Paver - min 108 lux (Workmanship)
  • Level 3 : T C Person - min 215 lux (High Visibility/Detailed Work)

Speaker Notes: The specification identified three levels of lighting, which would be required in certain circumstances.

Level 1 illumination was basic site lighting for safety, which was required where workers on foot would normally be carrying out their duties. The secondary benefit is that this level of light is also sufficient to carry out most highway construction activities.

Level 2 illumination was required more for checking workmanship. Level 2 lighting had to be provided for 30 meters behind the spreader so that mat defects could be identified and corrected immediately.

Level 3 illumination was the level of light achieved at the traffic control person stations.

Slide 56

Photo of a Photometer

Speaker Notes: This is the photometer, which I used to check on illumination levels through the duration of the project.

Slide 57

Photo of Lighting Units

Speaker Notes: The lighting units Municipal chose to use in this project had 4-1000 watt metal halide lamps on a 30 foot extendable mast.

Slide 58

Photo of a Municipal Employee Erecting a Light Tower

Speaker Notes: This is a photograph of a Municipal employee erecting the light towers. For most of the project Municipal had 16 towers set at 50 meter spacing which meant they could light 800 meters of roadway at any time. The towers were "leap-frogged" ahead with the moving operations.

Slide 59

Illumination Levels - 2 Lanes

Speaker Notes: The specification required that the contractor set up his full traffic control and lighting system for inspection by the Department prior to any work starting. This is a record of the illumination measurements made during the trial.

Slide 60

Photo of Illuminated Work Zone at Night

Speaker Notes: This photograph demonstrates Level 1 illumination. Most of the photos in this presentation have been taken without the aid of flash to help you appreciate the light levels on the site. You can see that the employees on the right are clearly visible under this level of lighting and it also provides a satisfactory level of light for working.

Slide 61

Illumination Levels - Spreader

Speaker Notes: This is a sketch of the illumination levels I measured behind the spreader before paving was allowed to begin. Municipal had to add additional lights to the spreader to achieve Level 2 illumination behind the paver.

Slide 62

Photo of Spreader in Daylight

Speaker Notes: Level 2 illumination behind the paver was achieved by the addition of a 1000 watt metal halide lamp and several halogen lamps.

Slide 63

Photo of Spreader Illuminating Work Zone at Night

Speaker Notes: This photo shows the spreader at work at night. You can see the higher level of light on the mat behind the paver.

Slide 64

Side-view Photo of Spreader at Night

Speaker Notes: In this view you can also see some of the other lighting that municipal added to the spreader. Lights were added to improve visibility in the hopper, on the operator deck and in the auger chamber.

Slide 65

Night Work Specification

  • Site Maintenance

Speaker Notes: Once we were satisfied that all the specification requirements had been met, it became important to ensure the Contractor complied with them for the duration of the project.

Slide 66

ATSSA"Guidelines for Work Zone Traffic Control Devices"

Speaker Notes: This is an example of a non-compliant cone. It has been sprayed with tack emulsion, which is covering its reflective stripes. The cone needs to be removed from service and cleaned.

Slide 67

Site Inspection

Speaker Notes: I developed a night work site inspection checklist, which covered all the areas of the specification to aid me in recording compliance from the contractor. Any deficiencies would be noted, I would discuss them with the contractor, give him a copy of the inspection form and then do a follow up inspection on subsequent nights.

Slide 68

Hwy 125 Night Work

  • Traffic Management

Speaker Notes: A comprehensive traffic management plan was used for this project.

Slide 69

Traffic Management

  • Restricted Work Periods
  • Emergency Vehicle Passage
  • Variable Message Signs
  • Media Announcements
  • Toll Free Information Line

Speaker Notes: The traffic management plan was used to try to minimize the delays to the users of Highway 125.

The components of the plan included restricted work periods, plans for emergency vehicle passage, variable message signs, media announcements and a toll free information line.

Slide 70

Traffic Management

  • Restricted Work Periods

Speaker Notes: Of course the most important traffic management strategy was the decision to work at night to minimize delays.

Slide 71

Traffic Management

  • Emergency Vehicle Passage

Speaker Notes: The efficient passage of emergency vehicles through the site was very important. Hwy 125 is a major route for all emergency services, especially ambulances because of the close proximity of the Regional Hospital to Exit 8.

Slide 72

Emergency Vehicle Passage

  • Emergency Services Meeting
  • Dedicated Site Contact
  • Traffic Control & Site Communications

Speaker Notes: We met with all the emergency services - Hospital, ambulance, fire, police and RCMP before work began to allow them to voice their concerns and to get ideas on how to best accommodate the passage of emergency vehicles. It was decided at this meeting that the contractor would provide a dedicated cell phone line on the site for contact by the 911 system operators. Municipal were also to develop an internal communications plan for dealing with the passage of emergency vehicles through the site.

Slide 73

Diagram of Emergency Vehicle Passage

Speaker Notes: The system worked like this: an ambulance on an emergency call en-route to the hospital would radio the 911 operator and give his estimated arrival time at the site, the operator would then call the dedicated cell phone line and inform municipal’s foreman, he in turn would use municipal’s radio system to alert traffic control persons, the pilot vehicle operator and others that an ambulance was coming and should be given priority for passage.

Slide 74

Traffic Management

  • Variable Message Signs

Speaker Notes: Variable message signs were employed to try to divert some of the traffic to alternate routes to decrease the number of vehicles arriving at the site.

Slide 75

Photo of Variable Message Sign

Text of Variable Message Sign: "Expect Delays"

Speaker Notes: The variable message signs were placed well in advance of the work site to provide information to motorists at locations where they had the opportunity to leave Hwy 125 and use an alternate route.

Slide 76

Typical VMS Messages

Speaker Notes: Here is an example of one message combination, which was used.

Slide 77

Photo of Variable Message Sign Text

Text of sign:

Speaker Notes: This portion of the message gives the motorist information that there is roadwork underway and where it is.

Slide 78

Photo of Variable Message Sign Text

Text of sign:

Speaker Notes: This part of the message alerts motorists to the consequences of proceeding on Hwy 125.

Motorists wishing to avoid delays would be tempted to take alternate routes. Those deciding to stay on hwy 125 would endure the delay, but hopefully be less aggravated because they knew what to expect.

Slide 79

Traffic Management

  • Media Announcements

Speaker Notes: The Department made use of a media consultant who had been hired to provide services on another highway project in the area to provide media releases for the project.

Slide 80

Regular Newspaper Updates

Images of newspaper clippings announcing work zones.

Speaker Notes: The consultant would release daily updates to local newspaper and radio, which would provide accurate information on where and when we would be working.

Slide 81

Traffic Management

  • Toll Free Information Line

Speaker Notes: The media consultant also provided a toll free information telephone line for the project.

Slide 82

Photo of Sign "HWY INFO LINE" with Phone Number

Speaker Notes: Motorists could call the info line to obtain timely and accurate information as to where and when we would be working over the next few days. There was also an option for callers to leave comments or complaints on voicemail for the project staff.

Slide 83

Hwy 125 - Trips During Construction

Speaker Notes: So lets review the traffic volumes on highway 125.

We have about 25,000 vehicles per day

That’s 175,000 vehicles per week

Which means almost 1.8 million vehicle trips on Highway 125 during the 10 week project.

Slide 84

Traffic Management - Success

Trips during construction > 1.5 million

Delay & work zone related complaints = 0

Speaker Notes: Even if we allow for some diversion of traffic at night, it’s likely we had over 1.5 million vehicle trips on Hwy 125 during the project period.

The total number of work zone and delay related complaints we received was zero!

Slide 85

? Questions ?

Slide 86

Contact Information

Gerard Kennedy, P.Eng.
Project Engineer
Nova Scotia Dept. of Transportation & Public Works
P.O. Box 1180
Sydney, N.S.
B1P 6J9
Tel (902) 563-2518
Fax (902) 563-2517

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