The BBC's Christian Fraser is travelling from Santo Domingo in the Dominican Republic to neighbouring Haiti, where people are struggling in the aftermath of a devastating earthquake. Here he keeps a diary of his journey along the road to Port-au-Prince.
19 JANUARY, 2200 GMT, PORT-AU-PRINCE
We have finally arrived at the airport in Port-au-Prince, after 10 hours on the road.
Among the biggest obstacles to the flow of aid from the Dominican Republic are the fears over security; legitimate concerns given the desperation that is growing along the route.
For the moment only two major convoys are leaving the border each day, always under military escort and never after dark. The plan is that over the next week the UN, with the help of the US military, will secure a humanitarian corridor from the border in preparation for stage two of the aid operation. And it will be needed.
The markets en route to Port-au-Prince did have food, fruit and water, but supplies are precariously low and basic commodities are getting ever more expensive. A volunteer from the Red Cross, whom we met on our arrival at the airport, says its operation is growing by the day but the logistical problems should not be underestimated - it could get worse here, he says, before it begins to get better.
19 JANUARY, 1815 GMT, ENTERING HAITI
Finally we're in Haiti. Lined up along the road into Haiti are the diggers and the heavy-lifting equipment that were so badly needed in Port-au-Prince in the first 48 hours after the quake. At this stage, it is more likely they will be employed in clearing vital supply routes than in search and rescue.
Travelling in the same direction is a bus full of worried relatives; many of them have still not had any contact from loved ones.
Motorbikes on Haiti's roads are heavily laden and fuel is scarce in the capital
"We don't know what we are going to find there," said Fernando, who flew into Santo Domingo on Tuesday from Miami. "We are worried sick. I have been calling my mother for days. I came as soon as I found the money to travel. I just pray she is still alive."
There are very few refugees coming from Port-au-Prince. Aid workers returning say there is no fuel in the capital and very few have the means to travel. Every motorbike that crosses into the Dominican Republic is loaded with jerry cans and suitcases. The border guards tell us this has been the quietest day so far.
After the initial flow of aid, the bigger aid agencies are waiting until the logistics are in place to send more supplies overland. This is hugely frustrating for the workers of smaller agencies who say they are more mobile yet under-utilised.
"The corporate donors have to trust us," said one. "We have the means and the intelligence on the ground to do more."
19 JANUARY, 1300 GMT, THREE HOURS FROM SANTO DOMINGO
Three hours into our journey, the road to the border is practically deserted. The long aid convoys we had expected to meet are nowhere to be seen.
19 JANUARY, 1130 GMT, BANI
At a service station in Bani, there are vehicles loaded with supplies and relief workers refuelling for the long journey ahead.
Roberto Ronza is leading an Italian team of doctors from the region of Lombardy. The Italians are supporting two medical non-governmental organisations and 70 volunteers who are fast running out of medical supplies.
Mr Ronza says they are sending scouts to assess what is needed along with 1.8 tonnes of desperately needed drugs and medical equipment.
The delivery came into Santo Domingo on holiday charter flights.
"We ran out of patience today. The airport is full, we can't wait any longer, we're heading into Haiti by road," he says.
Is he worried about security?
"We're told it's safe, we're told it has been secured by the UN. Who really knows? People are getting desperate."
18 JANUARY, 2200 GMT, SANTO DOMINGO AIRPORT
Even the most stoic Haitians are getting angry and impatient at the slow delivery of essential food and medicine, but some 500km (300 miles) away in the neighbouring Dominican Republic, things are finally beginning to take shape.
The apron at Santo Domingo airport is filled with aircraft from around the world. A search-and-rescue plane from South Africa made six refuelling stops just to get here. The UN reception centre is crammed with teams of impatient volunteers, all of them waiting for relief flights into Haiti.
Some, including a Swiss mountain rescue team, have been waiting since the weekend. In the cargo bay, the food, water and medicine is starting to arrive. They know they are working against the clock. Tonight they are loading 48 pallets of ready meals to send to the border.
The road to Port-au-Prince is dangerous and there are growing fears over security.
In the coming days, the UN is hoping that the military can secure a relief corridor to Port-au-Prince that will help speed up the process.
Chris Weeks, a logistics officer for DHL, has requisitioned the only available warehouse at the airport in preparation for the biggest deliveries.
The warehouse has no electricity and no key to open the main doors. They will sort it out, but it is a reminder that while the neighbouring Dominican Republic is a different world to Haiti, wealthy by comparison, it has limited infrastructure to help with this enormous relief effort that is gathering pace.