The month of April holds some significant dates for the environment. The month kicks off with National Walk to Work Day on April 2nd, National Walking Day on April 7th, and we round out the month with Earth Day on April 22nd. In honor of our environment, we wanted to highlight a couple of our recent pedestrian bridge projects that encourage more foot and less vehicle traffic.
The Eaton Street pedestrian bridge was built in 1912 as part of the Boston and Maine Railroad. In the 1990s, the City of Nashua repurposed the abandoned railroad into a recreation path called the Heritage Rail Trail. This trail connects the Tree Streets Neighborhood to downtown Nashua and its many restaurants, small businesses, and cultural landmarks. The City closed the bridge to pedestrian traffic in December 2019 due to timber deck and old railroad ties rot. Hoyle, Tanner completed a full structural inspection of the bridge and provided repair recommendations to the City so that the bridge could be re-opened; we also made maintenance recommendations so that the bridge can remain in usable condition for years to come.
To the north of the Heritage Rail Trail and in the center of the City is the 325 acre Mine Falls Park. The City of Nashua received NHDOT Transportation Alterative Program (TAP) funding to build a pedestrian link between Mine Falls Park and the Heritage Rail Trail. This project included many different design features in a small area such as an ADA complaint ramp system, a shared use shoulder along Everett Street, a crosswalk with flashing beacons at Ledge Street, and a prefabricated metal pedestrian truss bridge to cross the Nashua Canal. The crux of the project was to find a way to support the new bridge that would not increase or change the loading on the canal’s southern stone wall or northern earth embankment. To do this, we chose to use helical piles which transfer the bridge load into the ground below the canal. Helical piles have many advantages in urban locations because they can be installed with small construction equipment and with minimal ground vibration. The completed project was open to the public in June 2019.
Part of creating sustainable infrastructure is considering how people will use that infrastructure for years to come. The bridges we design must not only stand the test of time, but they must serve the community, as well as encourage more walkable and rideable communities!
If you have ever had a close encounter with wildlife while driving your car – glimpsed a deer, coyote or even a large turkey or raccoon at the side of the road – or worse, been involved in an accident caused by hitting wildlife – then you can understand how frightening and dangerous these situations are for a pilot flying a multi-million dollar airplane. Seeing a deer or coyote on the runway before take-off could cause a string of heart palpitations and sweaty palms!
Interactions between wildlife and aircraft can result in human injuries, even fatalities, along with injuries and fatalities to the animal, and costly repairs to damaged aircraft. The Federal Aviation Administration (FAA) – the federal transportation agency with the authority to regulate all aspects of civil aviation, including safety – has deemed prevention of wildlife from accessing airports as one of their primary safety concerns.
The first step to resolving any issue is identifying the extent of the problem: how many and what types of wildlife have access to the airport, where they come from, what attracts them to the airport, and how many interactions have occurred at the airport between wildlife and aircraft.
FAA keeps a National Wildlife Strike Database that is available to the public and provides accounting at each airport in the US of the wildlife strikes – or moments where a wildlife physically interacted with an aircraft. These strikes are reported annually and include data such as what type of animal, what type of aircraft, time of day, and height of the aircraft at the strike. Airport operations staff keep track of wildlife strikes and provide the data to FAA so that this database can be available for review. It is one important tool to assessing the extent to which wildlife interactions are an issue at an airport.
According to the National Wildlife Strike Database, deer and coyote are the most frequently struck terrestrial mammals (37 and 34 percent, respectively). Deer are responsible for 92 percent of the mammal strikes that resulted in damage. From 1990 to 2015, over 1,107 deer-aircraft collisions and 487 coyote-aircraft collisions were reported to FAA. Of these reports, 932 of the deer strikes (84 percent) and 43 of the coyote strikes (9 percent) indicated the aircraft was damaged as a result of the collision (FAA CertAlert No. 16-03, 8/3/2016).
Airports are also encouraged (or, if the airport is large enough, required), to complete a review of the airport for potential wildlife use and develop a plan for prevention of strikes per the FAA Advisory Circular 150/ 5200- 38–Protocol for the Conduct and Review of Wildlife Hazard Site Visits, Wildlife Hazard Assessments and Wildlife Hazard Management Plans. An airport is also required to complete these steps if there has been multiple wildlife strikes over a certain time-period, or there is a single strike that either affects an engine or results in substantial damage that would result in major repair or replacement of the aircraft.
These site reviews, performed by professionals trained in providing this type of review, coupled with the strike data over time, offer a good view of the potential risk at each airport for wildlife strikes.
The next step for an airport is to develop a Wildlife Hazard Management Plan, which identifies the specific actions the airport will take to mitigate the risk of wildlife strikes on or near the airport. Possible steps include:
reduction of habitat on the airport, including areas of water or vegetation (grasses and trees);
monitoring of the airport, runways, and taxiways, to quickly identify when wildlife access the airport and address the situation; and
steps that should be taken if wildlife are identified to prevent a strike from occurring.
Airports have a list of wildlife “harassment” techniques to scare wildlife away from the airport to prevent strikes that includes, some of which are similar to those you may use in your backyard garden- shiny or flashy pinwheels or reflective tape, or “googly-eyed” owl or hawk statues to scare away smaller birds. Loud noises, flares or even air cannons can be shot from a gun or cannon to scare wildlife and birds from the area.
One of the most effective ways to prevent wildlife strikes of medium- to large-sized mammals such as deer, coyotes and raccoons is to install a fence that surrounds the airport and prevents wildlife from physically entering the airport. This fence, sometimes referred to as a wildlife deterrent fence or wildlife exclusion fence, can be of varying heights and materials, but the FAA recommended design is an 8-foot chain link fence with three strands of barbed wire running along the top positioned so that the barbed wire sections are angled away from the fence to deter animals from climbing over the top. Often, the fence will have a horizontal bottom section called a “wildlife skirt” that is anchors the bottom edge of the chainlink fabric to the ground and is buried several feet deep to prevent animals from digging under the fence.
Hoyle, Tanner has assisted several of our aviation clients with installing, repair, and maintaining wildlife fences. One key project was initiated in 2012 after a wildlife strike between a plane and a deer at the Tweed New Haven Airport (HVN) in New Haven, Connecticut. This dangerous incident prompted FAA and Tweed New Haven Airport Authority to work together to plan for, fund, design, and install fencing to surround the airport to prevent future such interactions completely. This project had several challenges, including the fact that this airport is situated at the southern edge of Connecticut and has several areas of coastal marsh on the airport and freshwater wetlands that could not be avoided to achieve the goal of complete fencing. The success of this project was due to obtaining the required permits to allow for installation of the fence through wetlands from US Army Corps of Engineers (USACE) and CT Department of Energy and Environmental Protection (CTDEEP) while keeping the project on schedule and within the proposed budget. The fence was completed in 2014 to the cost of approximately $1.5 million.
Similarly, we assisted the Groton-New London Airport (GON) in Groton, Connecticut with the installation of wildlife fencing along several airport sections. However, because the southern side of the airport faces Long Island Sound, fencing could not be installed around all areas; fences must be offset from runways and taxiways by set distances so that they do not become hazards to aircraft as they take-off and land. In essence, the FAA design criteria for fencing ensures no trade-off between one problem (wildlife) to another (fences becoming hazards). The required offsets at this airport would have placed the fence into deep water within the tidal channel on the southern side, not a permittable action. As a compromise, we worked with airport staff, wildlife biologists, and state and federal permitting agencies to determine the best fencing locations to reduce the spots where wildlife could access the airport to the greatest extent feasible. This solution allowed airport staff to focus observation and deterrence measures in the unfenced areas, which resulted in better vigilance. This airport also installed a varying mesh fence, instead of a chain link, in areas that faced a public park so that the visual impact of the fence would be reduced while still providing an effective deterrent.
We also modified the fence to include a 6-inch opening in the fence bottom at set intervals to allow for the state-listed species of special concern northern diamondback terrapin to enter and exit fenced areas so that their nesting and feeding would not be interrupted.
Hoyle, Tanner has successfully worked with airport owners to assess wildlife hazards and install deterrent fences across New England. We have worked collaboratively with FAA and state permitting agencies in order to avoid or minimize natural resource impacts while meeting the goals of improving safety for the public, pilots and staff who utilize these airports. Contact us if you have any questions regarding wildlife at your airport and we would be happy to help!
Catie Hall Senior Marketing Coordinator and Definitely Not A Veterinarian
1. What drew you to Hoyle, Tanner? I actually always wanted to work at an engineering company. Both my parents were very technically-gifted, so I think I wanted to measure up in some way since I got a degree in journalism. At a time when I was looking for a job, this position popped up on my radar and I was eager to join! 2. What’s something invaluable you’ve learned here? I’ve learned that peace and challenge can co-exist. Hoyle, Tanner has a great culture and can feel like home – but it also encourages you to grow along with it. I’ve been up against very difficult deadlines but have still appreciated all the growth I’ve been able to experience here! 3. What’s your favorite time of year to work at Hoyle, Tanner? It used to be Christmas time because of the cheery energy and competition for Christmas decorations. But now I don’t think I have a favorite Hoyle, Tanner season – I like them all so long as the people around me are striving to be the best versions of themselves and adding to our culture. 4. What’s the coolest thing you are working on? I’m lucky right now to be working on the rebranding effort with the rest of my marketing team. It’s so interesting to witness the growth and change that’s taking place before us. I’ve seen people adopt new logos – but I’ve never seen the process of creating one. So neat! 5. What’s the best thing that’s happened to you so far this week? It’s warm enough to keep the window open and not shiver, and that’s a nice change. 6. How many different states have you lived in? Just Massachusetts, Vermont, and New Hampshire. But fun fact, I’ve lived in Vermont three different times after moving out of state! 7. If you could only eat one meal for the rest of your life what would it be? Nothing else matters except pizza and chocolate. I would eat pizza of all varieties followed by a dessert of some chocolate thing and I would be okay with that if it was my forever. 8. What kind of pet do you have and how did you choose to name it? I don’t have a pet right now, but do I look at adoptable dogs online all the time? You bet. Do I want to get a pug puppy and name it Claudia? Sure do. 9. What are three things still left on your bucket list 1. Write a Book 2. Get a Dog 3. Visit Alaska. Specifically Juneau (where the book “A Wolf Called Romeo” was written) 10. What characteristic do you admire most in others? I don’t know that there’s just one, and I don’t know that it would apply to everyone the same way. Honesty from one person might sound cruel whereas from another person, might be the best thing. I will say I really appreciate kindness and clarity from people, but there must be genuineness underlying it. I also appreciate curiosity. 11. How old is the oldest item in your closet? My parents and grandparents have given me so many old items over the years. I have furniture from my great grandmother that’s probably 80 years old? I have a tiny hat my parents gave me to wear when I was a baby, too. 12. Words to live by? Favorite Quote? “Do less, be more.” I love this quote. It’s a call to slow down and realize that just because you “do a bunch of things” doesn’t mean you “are a bunch of things.” I think we get swept up in tying our identity to our to-do lists and our activities and not enough in just appreciating the core of who we are without the distractions. 13. What did you want to be when you were growing up? A veterinarian! I held that dream close to my heart until I had to dissect a cat every day for a month in high school biology. That dream died with that cat. 14. If you were to skydive from an airplane what would you think about on the way down? Honestly, probably just “nope” till I was back on the ground.
Traffic modeling takes raw data (in the form of traffic counts and speed data) and builds a visual representation. This visual representation allows us to see how things interact with each other, which can be as simple as a stop-controlled intersection or as complicated as an entire city grid. The modeling allows us to look at how intersections perform in terms oflevel of service, traffic delay, and capacity utilized among other metrics.
Traffic modeling doesn’t just show how cars move in a straight line on a road. Instead, the modeling shows how traffic might back up at an intersection based on how much green (light) time each direction of traffic is given, how side roads are affected by long lines of vehicles, and what is happening at turn lanes. We also include pedestrians when there’s significant data for them; at small, rural intersections, there is not enough demand to show them in the model.
The level of serviceis the key metric for analyzing how well a signal functions. Level of service is categorized by five letter grades (A through F), but it’s really just an incremental delay in seconds. For example, if the average driver is stuck at a traffic light for less than 10 seconds, that’s level of service A. If it’s over 10 but less than 20, that’s level of service B, and so on. So really, the level of service is just a way to say this is the range of delay that the average person gets at this intersection. It’s key that it’s the average driver; so the first person who pulls up to a red light is likely going to be sitting there for more of the full signal cycle, but someone that arrives on green had a zero second delay – that’s why it’s key to measure the average.
Why it’s useful
I’ve been using the modeling software since I started here in 2013. It was pretty basic for the first few years, really just using it to model temporary signals; like if we had to go to a one-lane work zone with alternating directions of traffic, we’d use a temporary signal for that and need to model it to make sure the queues didn’t cause any big problems. In terms of how traffic modeling differs from pure calculations, it really has to do with its scale. You know, you can input some parameters into the software, and it runs all the iterations you need and can simulate random traffic patterns that a calculation wouldn’t be able to do. It also helps give you a visual representation of it. I could do a calculation that says, okay there’s a 300-foot queue here, but then when we put it in the modeling software, we can see that the queue is actually blocking a side road or spilling into the next traffic signal.
The flexibility to play around in the software is also significant. With a calculation, if you want to change something, you more or less have to restart the calc; but in the model, you can toggle a switch and it just completely changed your model – and you can change it back if you need to.
Our standard traffic modeling program is Synchro which is the static model, and then we also have SimTraffic which creates a video simulation of cars moving through the model. The video is the simulation of when the system is populated – that’s what uses the random traffic patterns, which is helpful because there is no calculation for random traffic patterns.You need to have the computer algorithm that best approximates random traffic driving patterns. With that simulation, you get to see how signals interact with each other; so you have one signal, and then you have another one 300 feet away; they might not be coordinated, but they will still influence the traffic patterns at each other, and it’s crucial to see what sort of problems they may cause.
What the challenges are
There are only minor downsides to traffic modeling software. There are so many different parameters in the programs that you might get a totally different result if you overlook one that’s buried deep in the dialogue boxes. In terms of reporting, there are also several different analysis methods you can get from the program. The simulation doesn’t change, but I can have the same traffic volumes and signal timing and still get three slightly different results based on the analysis method. There’s no significant difference, but depending on what the client or agency expects when they review it, it can impact the program’s options.
A good example is New Hampshire Department of Transportation (NHDOT) has published preferences for their report formats, but many clients do not have preferences, and so the lack of standardization can be a challenge.
Where it’s headed in the future
In the future, we will be using traffic modeling software more often. The developers of the traffic modeling software are continuously working on and releasing updates for the programs. We as designers are constantly trying to come up with new ways for traffic signals to be safer or to handle higher capacity. Sometimes, the software doesn’t have the availability to model those correctly because it’s a new innovation that hasn’t made it back into the software yet. So sometimes these updates are just the software catching up to what’s actually being in done in the field.
I expect there will also be some improved bicycle and pedestrian modeling capabilities. Right now, we can say there’s X number of bicycles per hour, but I envision software developers will be adding bicycle signal heads next to traffic lights because that’s an up-and-coming technology. It’s been tested in a couple of states already, and it could become an important part of traffic modeling software updates in the near future.
I’m part of a team that prepares traffic modeling projects for municipalities and state agencies across New England. Reach out to me with traffic questions or to learn more about NHITE.