For frequent travelers of mass transit, the engine’s rumble, the tracks’ chatter, and the varying temperatures are well-known sensations. We often accept noise and fluctuating temperatures as part of the journey, but what if they weren’t necessary?

Bus and rail car insulation has long relied on traditional fiberglass due to its fundamental thermal and acoustic qualities. However, this common material has disadvantages in terms of weight, moisture absorption, and practical performance, all of which compromise ride quality.

Companies like Polymer Technologies have worked diligently for years to come up with an alternative solution to this very common problem. Creating technology such as hydrophobic melamine foam to replace the fiberglass insulation gives customers a more comfortable ride and preserves the quality of the buses and rail cars for longer periods.

In this blog we will explore why mass transit vehicles should consider moving away from utilizing fiberglass insulation and move toward alternative foam options to enhance the quality of both the ride and the vehicles themselves.

The Limitations of Fiberglass in Mass Transit

For decades, fiberglass has been the standard insulating material in buses and rail cars, chosen for its low cost and basic thermal properties. However, as performance expectations for modern mass transit vehicles have evolved, the inherent limitations of this traditional material have become increasingly apparent.

These drawbacks affect several critical aspects of vehicle design and operation, from long-term durability and fuel efficiency to passenger comfort and the manufacturing process itself.

Moisture & Mold

One of the major drawbacks to having fiberglass insulation is that it doesn’t form a proper seal, creating problems due to the effects of weather and normal wear and tear. Fiberglass is porous to the point that it can trap in moisture which leads to mold, mildew, and erosion of the framing of the bus and rail car itself.

Over time, these issues can lead to a loss in insulation properties, causing the product to fail at its one purpose – protecting the vehicle and passengers from the elements.

Weight & Efficiency

While on its own a panel of fiberglass insulation isn’t that heavy. However, the sheer volume required to insulate a large bus or an entire rail car is substantial. Every square foot of insulation adds to the vehicle’s overall gross weight.

Add to that the common issue of fiberglass taking on moisture, these panels of insulation can quickly add up to hundreds of pounds of extra weight. This diminishes fuel efficiency, as heavier vehicles consume more fuel in shorter distances.

Acoustic Performance

While fiberglass insulation can be an effective material for acoustical absorption, its performance is significantly compromised when it gets wet.

The sound-dampening quality of fiberglass relies on the vast number of tiny air pockets between its fibers. These pockets are essential for trapping sound waves and converting their energy into heat, which is how the material reduces noise. However, when fiberglass becomes saturated, these critical air pockets fill with water.

Since water is not a good sound absorber, the wet fiberglass loses its ability to dampen noise, rendering it acoustically ineffective until it has completely dried out. This vulnerability to moisture makes it a less reliable choice for applications where condensation, humidity, or direct water contact are a concern.

Installation & Safety

While this point isn’t the most important one to consider when assessing the shortcomings of fiberglass insulation, it isn’t one that should be overlooked. Fiberglass isn’t an easy material to work with. In fact, handling it requires the use of personal protective equipment (PPE) due to its tendency to cause skin, eye, and respiratory irritation.

Also, fiberglass is extremely difficult to install due to its nature. Shaping fiberglass to fit nonstandard shapes isn’t easy. And, if there are any gaps between panels the insulation isn’t as effective as it could be on both an acoustic and thermal level.

The POLYDAMP® Hydrophobic Melamine Solution

Luckily, Polymer Technologies has created an effective alternative solution for the fiberglass insulation problem, POLYDAMP® Hydrophobic Melamine Foam. This foam option has many benefits that not only answer fiberglass’s shortcomings but surpasses even the benefits. So, let’s break each of them down.

Superior Moisture Resistance

The biggest drawback to fiberglass is that it absorbs moisture making the insulation less effective. Our POLYDAMP® Hydrophobic Melamine Foam (PHM) in its very nature is resistant to water. Because it is hydrophobic the foam actively repels water.

Ultimately, this inhibits the formation of mold and mildew, safeguards the vehicle’s structure from corrosion, and guarantees consistent insulation performance no matter the weather conditions. Given that buses and rail cars operate year-round, this final point is particularly crucial.

Ultra-Lightweight

A significant benefit of choosing foam over fiberglass is that foam is considerably lighter than its counterpart. PHM’s lightweight nature, in particular, helps to enhance the fuel efficiency of mass transit vehicles where stopping and starting is a frequent occurrence.

Also, mass transit vehicles are required to comply with strict carbon emission standards. Lowering the weight of the vehicles will directly reduce their carbon footprint and keep them in compliance with those standards.

Advanced Acoustic Absorption

Polymer Technologies melamine foams are designed with acoustic absorption in mind. It was our goal to ensure a quieter and smoother cabin environment for all vehicles utilizing this product.

With POLYDAMP® Hydrophobic Melamine Foam, the acoustic absorption goes above and beyond to ensure that all sounds from the vehicle itself (engine vibration) to the outside environment (tires on pavement or wheels on tracks) don’t make their way into the cabin of the vehicle. This ensures that mass transit customers and drivers have a more enjoyable riding experience.

Enhanced Safety & Easy Installation

When it comes to safety, POLYDAMP® Hydrophobic Melamine Foam is top notch compared to fiberglass. First and foremost, it isn’t fibrous, therefore cutting and handling it isn’t going to be a potential hazard to a person’s health.

POLYDAMP® Hydrophobic Melamine Foam has an excellent fire safety rating due to its non-melt, non-drip nature when exposed to high heat or fire. Instead, the foam chars and creates a fire-blocking barrier, significantly blocking the spread of fire, which is an ideal quality to have for mass transit vehicles. In fact, Polymer Technologies melamine foams meet and exceed Federal Transit Authority Docket 90 and NFPA 130, which require materials used in mass transportation have exceptional flame resistance, lower smoke generation, and lower toxicity emission properties.

A Better Experience For All

When looking at the pros and cons of choosing POLYDAMP® Hydrophobic Melamine Foam over fiberglass you also need to consider the individuals who will be affected by the decision. When it comes to insulation for buses and rail cars there are three groups of people who directly benefit: the passengers, the transit operators, and the vehicle manufacturers.

For passengers it is all about how much quieter and more comfortable the ride is with PHM. When looking at the operators the benefits come from higher fuel efficiency, reduced maintenance costs, and improved durability in the vehicle. Finally, for manufacturers, assembling these vehicles is much easier and safer with a foam option vs a fiberglass one.

If you are looking for more information about POLYDAMP® Hydrophobic Melamine Foam (PHM), please reach out to Polymer Technologies. We are happy to answer any of your questions and get you started with a consultation today.