Paving your Way to Success
Parking has become so techno-centric that it could be easy to forget the traditional old-school challenges facing parking owners and operators. One of the most fundamental issues facing owners, particularly owners of outdoor parking lots, is pavement management. Surface parking lots present owners with an often-frustrating paradox: as hardy as pavement is, it’s also one of the most fragile elements of any parking facility.
Parking lot owners are often surprised to find that the pavement in their lots can be one of their most expensive assets to maintain.
It’s an issue that can’t be taken lightly. A run-down parking lot creates an unattractive and unwelcoming impression on parkers, and perhaps more importantly, a derelict lot can also pose potentially hazardous conditions for drivers and their vehicles. Not only can this make a lot less attractive to drivers (prospective parking customers), but it can also lead to costly legal liability if parkers suffer personal injury or damaged vehicles.
Yet, despite the obvious hazards that can be caused by an improperly maintained parking lots, many owners and operators still treat their lots as an afterthought. While it’s true that the typical lot requires less maintenance than a parking structure, proper maintenance is still essential. A parking lot’s pavement undergoes a great deal of wear and tear every day from vehicles and it’s essential to have an assessment and maintenance plan to preserve the property’s aesthetics, ensure parker safety, and extend the service life of the pavement.
Parking lot owners are often surprised to find that the pavement in their lots can be one of their most expensive assets to maintain. However, these costs can be minimized. It’s merely a matter of recognizing the warning signs of asphalt distress and taking action.
There are seven primary types of asphalt distress, any one of which can require repair. The good news is that a pavement evaluation program, led by a trained and experienced pavement assessor, can identify potential problems before they require major overhauls, saving owners and their property managers tens of thousands of dollars.
Six Signs of Trouble
The first sign of trouble appears in the form of longitudinal cracks. Longitudinal cracks typically appear along joints, which are the most vulnerable part of the pavement. They can result from poor joint construction or location, or they may be an indication of weakness within the stabilizing base below. While longitudinal cracks are merely an early form of deterioration, they can trigger major problems down the line by allowing moisture to permeate the concrete.
The next common form of deterioration is transverse cracking, which extends across the pavement perpendicular to longitudinal joints. Transverse cracking usually results from shrinkage of the stabilizing base below and is often related to low temperatures impacting the asphalt. Transverse cracking is also often an indication that the stabilizing base is also cracked.
As longitudinal and transverse cracking increase in magnitude and density, they form block-like patterns called block cracking. Block cracking is a series of interconnected cracks that appear as rectangular pieces. Like longitudinal cracks, block cracking can also allow moisture to infiltrate the asphalt, which can undermine the pavement.
When aggregate or asphalt binder materials wear away at the surface, raveling results. Raveling is essentially the disintegration of the asphalt causing pieces of the pavement to come loose. This can lead to gaps within the pavement surface, roughening of the surface, and the formation of puddles, which can lead to vehicle hydroplaning and other related problems.
While these first four types of deterioration are signs of trouble, they can often be treated with inexpensive preventative maintenance procedures such as the application of a crack seal or seal coat. Unfortunately, many owners and their maintenance consultants unnecessarily utilize more costly reconstruction, and as a result end up spending thousands of dollars more than necessary to repair what are essentially simple and common issues.
That said, higher density cracking and higher severity raveling often do require more complex and costly interventions. For instance, rutting is a permanent deformation of the pavement that occurs when ruts appear in the subgrade beneath the pavement. There are two basic types of rutting: mix rutting and subgrade rutting. Rutting is often the result of errors committed when the lot was initially developed, such as inadequate pavement structure or insufficient compaction of base layers during construction.
When the subgrade is no longer able to support the pavement structure, fatigue cracking will set in. Fatigue cracking, or alligator cracking, resembles an alligator skin’s diamond-shaped pattern. Both rutting and fatigue cracking are indications that, in addition to the obvious surface deterioration there is also significant corrosion in the asphalt below the surface. If they are ignored, these issues can cause the pavement to settle or depress, which leads to the formation of potholes.
These more advanced forms of deterioration typically call for mill and overlay rehabilitation, a much more expensive form of rehabilitation that requires the stripping of the top layer with heavy machinery and then the reapplication of a new surface. That’s why it’s so important to identify the warning signs and resolve early premature distress before these major—and much more expensive—problems appear.
If you catch the damage too late and find there’s already potentially significant pavement damage it is advisable to turn to a pavement specialist. Proper repair requires a number of different types of expertise, including geotechnical engineering, observation and testing for pavement design. It also requires expertise in all aspects of pavement engineering, including surface and subsurface investigation, pavement evaluation, forensic failure analysis studies, pavement design, pavement management systems, and construction quality assurance and quality control.
When planned and implemented properly, a parking lot’s pavement management program can extend the useful life of the lot by many years and save owners tens of thousands of dollars by avoiding unnecessary repair and replacement costs.
Stacie Steel, PE is a Principal Professional with Kleinfelder. She can be reached at SSteel@kleinfelder.com.