The Proposal

Fonlanfè has long been an obstacle for the people of Boucan Carré. However, it now stands in the way of PIH/ZL's mission to provide much-needed healthcare in this remote area of the Central Plateau. For several years, PIH/ZL has attempted to gather the resources necessary to construct a bridge. After being denied governmental and international development agency assistance, PIH/ZL asked Chris Strock, a U.S. based engineer, to work with local PIH/ZL staff and engineers to survey a bridge site, develop an appropriate bridge design and write a corresponding construction proposal. The results of these efforts can be seen in the following proposal. Included are details of the proposed bridge design – a reinforced culvert crossing that requires minimal long-term maintenance and can withstand flood waters without washing away. This design allows for relatively low construction costs, while providing the greatest long-term usage.

Now that the plan is in place, all that remains is funding. After again seeking and being denied government assistance, Chris Strock and other PIH supporters developed Bridgeforhaiti.org as a means of educating the public and raising the necessary funds. Once the project funding goal has been met, Chris Strock, PIH/ZL staff and local labor forces will oversee construction of the bridge. In keeping with the PIH model of community health workers, final construction plans rely on the use of local materials and labor forces in an effort to stimulate local economies and build a long-term personal investment for the people Boucan Carré.

Partners In Health / Zanmi Lasante
Increasing access to health care in Haiti's Central Plateau
A proposal for a bridge over the Fonlanfe

1.0 Introduction and Need

Partners In Health (PIH) is a United States-based 501(3)(c) non-profit organization that is dedicated to providing a "preferential option for the poor" through health care programs in impoverished communities. By rebuilding public health infrastructure, training community health workers, and enlisting local capacity, PIH has successfully challenged those who claim that quality health care is impossible to deliver in resource-poor settings. In Haiti, PIH has worked since the 1980s with its sister organization, Zanmi Lasante (ZL), to provide health care and social services, strengthen the public sector, and improve the overall well-being of impoverished rural communities in the poorest country in the Western Hemisphere.

Zanmi Lasante currently operates at nine sites, each of which boasts a clinic or hospital serving populations that previously had little or no access to even basic health services. In the village of Boucan Carré, PIH/ZL staffs and runs a public clinic that sees an average of 200 patients per day at no cost to the patient regardless of the type of the care they receive. Vehicles and pedestrians must cross a river called Fonlanfe (literally translated from Haitian Creole as "The Deep Hell") to reach the clinic. The typical peasant travels on foot and must wade through waist-deep water across a very rocky and uneven riverbed. During the rainy season, Fonlanfe is often impassible. Urgent deliveries of medical supplies and food have often been delayed or denied altogether. Patients and staff members alike, whether on foot, horse, motorcycle, or sport utility vehicle, are regularly stranded on either side of the river for hours waiting for waters to recede. Vehicles (including PIH/ZL ambulances) have been swept away by sudden floods. People have even drowned during attempted crossings to seek medical care.

The lack of adequate infrastructure also increases the cost of living in Boucan Carré because of the premium that is added to transported goods and services. Furthermore, access to education and markets are restricted perpetuating an endless cycle of poverty in this already poor area.

The peasants of the Central Plateau deserve a permanent river crossing that can improve traveler safety, increase access to health care and social services, and decrease the economic burden on the residents of Boucan Carré and on PIH/ZL's operations. The Government of Haiti (via financing from internal revenue taxes and/or international aid donors) is typically responsible for the provision and maintenance of transportation infrastructure to include bridges. After meeting with representatives from the Ministry of Transportation and the United Nations, this area of Haiti is not a primary priority for such state-sponsored projects. Thus, PIH/ZL will implement this project to meet the needs of its patients. As such, this proposal seeks US$250,000 through private donors in order to build the bridge recommended in this document.

Figure 1. Peasants must forge the Fonlanfe River in order to reach health care, schools, and markets

2.0 Project Summary

A permanent river crossing would meet the needs of patients, residents and PIH/ZL in and around Boucan Carré. The preconstruction efforts leading up to construction already completed include: 1) a field investigation; 2) development of design criteria to meet existing site conditions; and 3) engineering recommendations incorporating site specific data and design criteria. This proposal includes a detailed description of each item offering a feasible solution for a permanent crossing. It includes sections of the site location, site evaluation, design philosophy and recommendations (including design factors, design criteria, and advantages and disadvantages of a Reinforced Culvert Crossing.

3.0 Site Location

The proposed site is an existing crossing point located along the road from Domonde to Boucan Carré. Refer to Figures 2.1 and 2.2. Site Evaluation

Figure 3.1 Approximate location of Boucan Carré

Figure 3.2 Aerial of the existing river crossing

4.0 Site Assessment

Zanmi Lasante performed a site assessment in August 2006 during the height of the rainy season. The assessment addressed the following items:

Crossing Location: The existing crossing run diagonally across the river.
1. One option is to make the new bridge here (total length is 100m).
2. Another option is to move down river parallel to the river and at a narrower point (total length is 30m).
Geotechnical: The general soil classification of banks and surrounding area is silty-sand intermixed with clay, cobbles, and gravel.
1. The riverbed consists of large stones overlaying similar material.
2. This material can be compacted to 95% compaction using appropriate methods and used extensively in the region as backfill material.
3. This material is well suited as backfill material and under lying abutments if compacted to a minimum of 90% compaction.
Land survey: A topographical survey using an auto-level and measuring rod identified two cross sections across the two crossing locations.
1. The typical low section, where the current crossing exists, consists of a river width of 32m +/-, a top-of-bank to top-of-bank width of 100m, and variable depths (150mm to 1.2m) as shown in Figure 4.1.
  
  Figure 4.1 Cross-section of existing crossing location, not to scale
2. The typical high section consists of steep, well-defined and stable banks (2m above the water level at the time of the survey) with a water and top-of-bank to top-of-bank width of 30m +/-. The typical mid-section water depth during the time of the survey was 1.2m as shown in Figure 3.2.
  
  Figure 4.2 Cross-section of possible down river crossing location, not to scale.

5.0 Design Philosophy

Engineers typically build bridges above a certain flood plane (10-year, 100-year, etc.). Figure 5.1 shows a composite steel and concrete bridge and Figure 5.2 shows a metal truss bridge (i.e. Bailey Bridge or Mabey-Johnson Bridge) used for this purpose and are common throughout Haiti. The flood plane at the existing crossing location is very wide. Thus, a design for a structure similar to either Figure 5.1 or 5.2 must elevate the road section very high to prevent the floods from washing away or damaging the bridge. Figure 5.3 shows the approximate flood plane during a typical flood. Note that hydraulic data is not available to determine specific flood levels.

Figure 5.1 Steel-concrete composite bridge

Figure 5.2 Metal truss bridge

Figure 5.3 Approximate location of Fonlanfe flash-flood plane shown in red

Another option is to design a structure within the flood plane. Such a design must include special features to decrease damage during floods and prevent washout. A reinforced culvert crossing meets these criteria. Traditional, non-reinforced culvert crossings are common throughout Haiti as shown in Figure 5.4.

Figure 5.4 Traditional, non-reinforced culvert crossing The community of Boucan Carré will be responsible for maintaining the bridge. Thus, it must be low maintenance and inexpensive to repair.

6.0 Design Factors

As with all civil infrastructure projects, special factors must be considered during the design process. For the Fonlanfe crossing, the following factors have been evaluated:

Bridge load: Typical vehicle traffic consists of the equivalent of a sport utility vehicle crossing an average of ten times per day. Periodically, single-unit delivery trucks with an estimated gross weight limit of 30,000 lbs/13,600 kg should be able to make the crossing.
Wind load: Haiti is located in the hurricane belt of the Caribbean, where sustained winds could reach 150 mph/240 kph. No wind loading calculations have been performed for the proposed bridge alternatives presented in the following section as their profiles are considered low-risk for wind-associated failure.
Seismic conditions: Haiti is located on the northern edge of the Caribbean Plate and on the southern bank of the Hispaniola Trench, an active seismic zone subject to earthquakes potentially greater than magnitude 7.0. While seismic failure is a potential, no specific structural measures have been provided for seismic loading for any of the alternatives. However, based on prior studies with bridges of the type recommended in this proposal, damage due to seismic activity was shown to be minimal up to magnitude 5.7 and Haiti has not experienced an earthquake greater than magnitude 4.1 since 1991.
Hydraulics: No official rainfall data exists for the region. Local residents were interviewed to assess the extent of flooding, and it was determined that the river overtops its banks at least once annually. Potential failures associated with turbulent flow and overtopping include the following:
- Uplift - water flowing at a high velocity over the road surface can lift away the surface, acting much like an airplane wing;
- Down Slope Erosion - the overtopping water is very turbulent and can erode the downstream portion of the river bed until there is a breach in the underside of the structure;
- Exit Scour Ð flow through or under the bridge will be concentrated, thus increasing the velocity of the water on the downstream side of the structure through the culvert such that the water scours out the downstream channel and undermines the slope, abutments and/or culverts; and
- Loss of Backfill Material (for the culvert crossing option) - the velocity of the water can pull backfill material (specifically small grained sand particles commonly referred to as "fines") through the seams and holes in the culverts until the road is undermined.

7.0 Bridge Design Criteria

The bridge type selected will be required to meet the following criteria:

life cycle of 50 years with minimal maintenance
minimum H-15 loading (an H-15 loading is represented by a two-axle single unit truck weighing 30,000 pounds (15 tons) with 6,000 pounds on its steering axle and 24,000 pounds on its drive axle)
cost effective
use of straightforward construction methods that maximize the local labor force and available materials (primarily river sand and stones) to include procurement and transportation to the site
capable of withstanding the possibility of annual flooding over the bridge deck

8.0 Project Recommendation

This report recommends the construction of a reinforced corrugated metal pipe arch culvert crossing (i.e. reinforced culvert crossing) for Pont Fonlanfe. The recommendation is based on similar bridges in the region, such as a local bridge that has been in use for more than 20 years along the Boucan Carré road (refer to Figure 5.4). This solution successfully accounts for all design factors and meets all design criteria. Local workers can build this bridge and have experience in maintaining similar structures. The bridge recommended passes a maximum flow of 1,000 cubic feet per second and maximum river depth of more than 3m that can remain operational during moderate flooding. The design reduces the force of turbulent flows and the associated risk of washout as shown in Figure 8.1 with:

Sloped side walls and beveled culverts;
Reinforced concrete deck structurally attached to the bridge;
Inlet and outfall protection to protect against exit scour; and
Vertical "curtain walls" at both ends for washout protection via undercutting.

Figure 8.1 Reinforced culvert crossing, typical section

The design includes six to ten corrugated metal pipe arch culverts (3.9m x 2.4m) as shown in Figures 4.1 and 4.2. Concrete will encase the culverts and river stone faces the walls for a pleasant aesthetic look.

Advantages of this option include:

proven effectiveness in the region;
simple construction techniques currently used by local laborers using local materials;
metal plate sections used to construct pipe arch culverts can be easily transported;
reliance on local labor;
low maintenance using local expertise;
moderate costs; and
structural integrity for H-15 loading and against flood waters.

Disadvantages include:

difficultly procuring corrugated metal plates for culverts; and
long (approximately three months) and seasonal construction period (i.e. during the dry season).

9.0 Conclusion

By describing the need and a viable solution in this proposal, PIH hopes to engage partners to help finance the construction of a bridge over the Fonlanfe. PIH believes this project will be successful with the active support of local community members and associations and private donors, specifically U.S.-based civil engineering and construction firms. A bridge across the Fonlanfe provides a preferential option for the people of Boucan Carré by improving traveler safety, increasing access to the broad range of health and social services available at the PIH/ZL clinic, and increasing access to schools, markets and improved wellbeing.

Zanmi Lasante has already provided an in-kind donation for the site assessment, bridge design and construction estimate worth more than USD20,000 and will continue its efforts to do whatever it takes to complete this project. With this proposal, we are seeking an additional USD250,000 to build the bridge.

Prepared by:

Chris Strock, P.E.
Myers-Lawson School of Construction at Virginia Tech
Blacksburg, Virginia
e-mail: cstrock@vt.edu
Phone: +1 804-512-3933

Ted Constan
Vice President for Program Management
Partners In Health
641 Huntington Ave, 1st Floor
Boston, Massachusetts 02115 USA
Phone: +1 617-432-5256
Fax: +1 617-432-5300
e-mail: tconstan@pih.org
website: www.pih.org